Many unit operations, especially those that do not involve heat, have little or no effect on the nutritional quality of foods. Examples include mixing, cleaning, sorting, freeze-drying, and pasteurization. Unit operations that that intentionally separate the components of foods alter the nutritional quality of each fraction compared with the raw material. Unintentionally separation of water-soluble nutrients (minerals, water-soluble vitamins, and sugar) also occurs in some unit operations (for example blanching, and in drip losses from roast or frozen foods).
Heat processing is a major cause of changes to nutritional properties of foods. For example, gelatinization of starches and coagulation of proteins improve their digestibility, and anti-nutritional compounds (for example a trypsin inhibitor in legumes) are destroyed. However, heat also destroys some types of heat-labile vitamin, reduces the biological value of proteins, (owing to destruction of amino acids or Maillard browning reactions) and promotes lipid oxidation.
Oxidation is a second important cause of nutritional changes to foods. This occurs when food is exposed to air (for example in size reduction or hot-air drying) or because of the action of heat or oxidative enzymes. The main nutritional effects of oxidation are:
1.The degeneration of lipids and subsequent reactions to form a wide variety of carbonyl compounds, hydroxy compounds and short chain fatty acids, and in frying oils to toxic compounds.
2.Destruction of oxygen-sensitive vitamins.
The importance of nutrient losses during processing depends on the nutritional value of a particular food in the diet. Some foods (for example bread and milk) are an important source of nutrients for large numbers of people. Vitamin losses are therefore more significant in these foods than in those, which either are eaten in small quantities or have low concentration of nutrients.
In industrialized countries, the majority of the population achieve an adequate supply of nutrients from the mixture of foods that is eaten. Losses due to the processing of one component of the diet are therefore insignificant to the long-term health of an individual. In an example, complete meals, which initially contained 16.5 micro-grams of vitamin A lost 50% on canning and 100% after storage for 18 months. Although the losses appear to be significant, the original meal contained only 2% of the recommended daily intake (RDA) and the extent of loss is therefore of minor importance. The same meal contained 9 mg of thiamin and lost 5% after 18 months’ storage. The thiamin content is ten times the RDA, and adequate quantities therefore remained. Possible exceptions are the special dietary needs of pre-term infants, pregnant women, and the elderly. In these groups, there may be either a special need for certain nutrients or a more restricted diet than normal.
Variation in nutrient losses between cultivars or varieties can exceed differences caused by alternative methods of processing. Growth conditions, or handling and preparation procedures before processing, also cause substantial variation in nutrients loss.
Sunday, August 22, 2010
Saturday, August 21, 2010
Retinol (Vitamin A)
Foreword
Vitamins are minor but essential constituents of food. They are required for the normal growth, maintenance and functioning of the human body. Hence, their preservation during storage and processing of food is of far-reaching importance.
The vitamin requirement of the body is adequately supplied by a balanced diet. A deficiency can result in hypovitaminosis and, if more severe, in avitaminosis. Both can occur not only because insufficient supply of vitamins by food intake, but can be caused by disturbances in resorption, by stress and by disease.
An assessment of the extent of vitamin supply can be made by determination of vitamin content in blood plasma, or by measuring a biological activity which is dependent on the presence of a vitamin, as are many enzyme activities.
Vitamins are usually divided into two general classes: the fat-soluble vitamins, such as A, D, E, and K, and the water-soluble vitamins B1, B2, B6, B12, nicotinamide, pantothenic acid, biotin, folic acid, and C.
Biological Role
Retinol is of importance in protein metabolism of cells, which develop from the ectoderm (such as skin or mucous-coated linings of the respiratory or digestive systems). Lack of retinol in someway negatively affects epithelial tissue (thickening of skin, hyperkeratosis) and causes night blindness.
Requirement and Occurrence
The daily adult requirement of vitamin A is 1.5-1.8 mg. Approx. 75% is provided by retinol intake (as fatty acid esters), while the remaining 25% is through beta-carotene and other provitamin active carotenoids. Due to the limited extent of carotenoid cleavage, at least 6 g of beta-carotene are required to yield 1 g retinol.
Vitamin A resorption and its storage in the liver occur essentially in the form of fatty acid esters. Its content in liver is 250 micro grams/grams fresh tissue, i.e. a total of about 240-540 mg is stored. The liver supplies the blood with free retinol, which then binds to protein in blood. Vitamin A concentration is 45-84 micro grams/100 milliliters plasma in adults; values below 15-24 micro g/100 ml indicate a deficiency.
A hypervitaminosis is known, but the symptoms disappear if the intake of retinal is decreased.
Vitamin A occurs only in animal tissue, above all in fish liver oil, in livers of mammals, in milk fat and in egg yolk. Plants are devoid of vitamin A but do contain carotenoids, which yield vitamin A by cleavage of the centrally located double bond (provitamins A)
Carotenoids are present in almost all vegetables but primarily in green, yellow, and leafy vegetables (carrots, spinach, cress, kale, bell peppers, paprika peppers, tomatoes) and in fruit, with outstanding sources being rose hips, pumpkin, apricots, oranges and palm oil, which is often used for yellow coloring. Animal carotenoids are always of plant origin, derived from feed.
Stability and Degradation
Food processing and storage can lead to 5-40% destruction of vitamin A and carotenoids. In the absence of oxygen and at higher temperatures, as experienced in cooking or food sterilization, the preferential reactions are isomerization and fragmentation. In the present of oxygen, oxidative degradation leads to a series of products, some of which are volatile. This oxidation often parallels lipid oxidation. The rate of oxidation is influenced by oxygen partial pressure, water activity, temperature, etc. Dehydrated foods are particularly sensitive to oxidative degradation.
Tuesday, August 17, 2010
Major Modes of Food Degradation
Preharvest Biological Decay
Before harvest and slaughter, plant and animal foods are subject to a myriad of microbiological diseases including viruses, molds, yeasts, and bacteria. In addition, some foods before harvest can be attacked and diseased or eaten by insects, birds, and rodents. For plants, competition by weeds can result in poor yield. To prevent or control this, one form of processing is the use of chemical or physical means of control or prevention. The use of pesticides, and herbicides are examples of chemical control. Another method of chemical control is the use of drugs such as antibiotics to prevent disease in animals prior to slaughter. Weeding by machine is a physical means of control. These modes of deterioration are not generally considered about shelf life or open dating. However, if the food is subjected to damage, its initial quality will be less. Processing does not make low quality foods better, and overall shelf life will be less after slaughter or harvest than with undamaged foods.
Senescence
Once a fruit, vegetable, cereal grain, or animal product is slaughtered, it is separated from its source of nutrients and water. However, since it is still a viable living system, the enzymes present continue to operate and utilize the available carbohydrate and nutrient stores. For fruits, this process can be of benefit because they can repair post harvest damages, and more important, fruits can be picked prior to optimum maturity, transported long distances to the marketplace and home, and then develop into a high quality product.
For all foods, however, eventually enzymatic biochemical processes occurring post harvest lead to degradation, including loss of color, flavor, nutrients, and texture. In addition, the breakdown products produced damage the tissue so that the foods become subject to microbiological attack with subsequent more rapid decay. To prevent this mode of deterioration, three major processing methods can be used: (1) lowering of temperature slows the reaction; (2) raising the temperature denatures the enzymes and makes them inactive; and (3) removal or binding of water reduce availability (or water activity), which reduces the ability of the enzymes to operate.
Microbiological Disease
Microorganisms constitute a major mechanism by which many foods, especially fresh ones, lose their quality. This is because microbes are ubiquitous in the environment, and can grow rapidly. After a food is harvested or slaughtered, it loses some degree of its ability to fight off microbial attack. If it is physically damaged, then it becomes more susceptible to attack. Bruising, cutting, and trimming constitute such damage. Microbes can grow rapidly on foods (starting with one microbe which divides every 10 min, with sufficient available nutrients, in five hours there would be over one billion microbes present). The basic principle of preservation is to control or destroy them. Much the same controls, are employed as those used for enzymes:
(1) Lower temperature to slow growth.
(2) Raise temperature to kill them.
(3) Remove or bind water to slow or prevent their growth.
(4) Lower pH to slow or stop their growth by adding-acid or fermentation.
(5) Control O2 or CO2 level to control population.
(6) Manipulate food composition to remove nutrients needed by the microbes.
Because in some cases the above methods change the food into a form not desirable by the consumer, chemical means of preservation can be used. These chemicals are used to slow growth or kill the organisms. At the level of use, the chemicals should have no ill effect on the consumer. Examples are the use of calcium propionate in bread and sodium benzoate in some soft drinks.
Knowledge of the rate of growth of microbes as a function of the environmental conditions of the food is very important in the prediction of shelf-life and, thus, the open dating of some foods such as: fresh and ground meats and fresh poultry; fresh fish; dairy products such as milk. Cheese and yogurt; cured meats such as hot dogs, bacon, and bologna: pasteurized fruit drinks; fruits and vegetables; and whole grains.
A second and more serious problem with microorganisms is the fact that some are pathogenic to humans, i.e., they either cause infection when ingested or result in the production of chemicals in the food, which are toxic to humans. Most food processes are designed to guard against contamination with pathogens and the subsequent growth of these pathogens after processing, or as important, to treat the food in such n way as to destroy any potentially harmful microbes that might be inadvertently present in the food. For example, fermentation of foods with useful microbes results in alcohol or acid production. The acid and alcohol prevent the growth of pathogens.
Chemical Deterioration
During the processing of foods, tissue damage occurs which causes the release of various food chemical constituents into the cellular fluid environment. These chemicals can then react with each other or with external factors to lead to deterioration of the food and result in a shortening of the shelf life. Many different reactions can occur which lead to quality and nutrient loss. The major ones are classified below.
Enzymatic
The normal post-harvest enzymatic reactions can lead to a loss in food quality and shelf life. In addition, destruction of cell tissues releases enzymes, which can lead to further deterioration. This reaction is usually very rapid at room temperature, but is controlled in the natural state. Once the food is handled, deterioration starts. Enzymatic decay also occurs in the frozen state unless the enzymes are previously denatured by blanching. Enzymatic reactions also lead to the major mode of deterioration of many refrigerated dough. Unfortunately, heat treatment to denature the enzymes results in loss results in loss of dough functionality. Control of the enzymatic reactions is the same as was discussed for senescence. Knowledge of the rate of these reactions as a function of environmental conditions is very important in prediction of shelf life for open dating. The major environmental factors are oxygen, water, pH, and temperature. Other enzymatic degradations include color losses and vitamin tosses such as for vitamin C.
Lipid Oxidation
Many foods contain unsaturated fats, which are important in the nutrition of humans. Unfortunately, these fats are subject to direct attack by oxygen through an auto catalytic free radical mechanism. This results in the production of rancid off-flavors, which make the food undesirable to consume. Very little fat has to oxidize for the consumer to detect rancidity and reject the food. Unfortunately, the food will still be very nutritious. The free radicals and peroxides produced in this process can react and blench pigments, such as occurs in dried vegetables, and can destroy vitamins C, E, and A. They can also result in protein degradation, making it of poorer quality, as can happen in whole dry milk; can cause darkening of the fat as happens in deep fat frying; and produce toxic substances which have been implicated in some animal studies as potential carcinogens.
Knowledge of the rate of lipid oxidation is important in foods where it be the principal mode of deterioration, for example:
(1) Fried snacks,
(2) Nuts,
(3) Dried meats/vegetables/fish/poultry,
(4) Cereals,
(5) Wheat germ,
(6) Frozen vegetables/meats/fish/poultry,
(7) Some dairy products,
(8) Semi-moist meat products,
(9) Pre cooked refrigerated meats and fish,
(10) Cured meat and fish, coffee, cooking and salad oils, margarine, spices, and dried vegetables such as potatoes and carrots.
Non Enzymatic Browning (NEB)
Non Enzymatic Browning (NEB) is another major chemical reaction leading to a loss of quality and nutritional value. This reaction is the result of reactions between reducing compounds (such as glucose, fructose and lactose) and proteins or amino acids. Browning can also occur as the result of heating sugars to very high temperatures or through the oxidation of vitamin C. In certain cases the reaction is desirable, such as in the toasting of the bread, the crust formed in roasting meats, malting of barley for beer and spirits manufacture, and the production of syrups, molasses, and caramel candies.
Other Chemical Reactions
Other chemical reactions that can lead to food degradation include the thermal destruction of vitamins such as A, B, and C, the effect of light an pigments such as occurs in the browning of meat and bleaching of chlorophyll, the direct oxidation of vitamin C, the effect of light on riboflavin, and the direct oxidation of carotenoid pigments and the loss of flavor through some mechanism. In ever case the effect of temperature, oxygen level, moisture content, and light must be known for the rate of the reaction to be predicted and the time to reach end of shelf life measured. Of importance in all these reactions is a decision as to what extent of degradation is considered to be the end of shelf life.
Physical Degradation
Physical damage can also lead to loss of shelf life. The types of physical damage can be classified into the following categories.
Physical Bruising/Crushing
This mode of deterioration is related to physical abuse of in food harvest, processing, and distribution. It is particularly important to fruits and vegetables, since physical abuse leads to microbial attack and decay. Packaging to prevent abuse is key to long shelf life. With dry materials such as chips, crushing can lead to unacceptability based on consumer desires.
Wilting
Fresh leafy and tuber vegetables can deteriorate if subjected to low relative humidity, losing moisture to their surroundings. This results in loss of crispness and an increased rate of senescence reactions with subsequent quality and nutrient losses. Proper knowledge of the rate of moisture loss for various packaging materials and the maximum allowable moisture loss can be used as one means of setting open dates for fresh produce.
Moisture Loss/Gain
With some food products such as candy, semi moist pet foods, cakes and bread, moisture loss leads to an increase in hardening. If a limit of hardness is known to be unacceptable then predictions to reach this level based on equations which describe the moisture change with time, can be used as one method of prediction of end of shelf life. From this, the open date for best quality can be set. These same equations can be used to predict the moisture loss of flour, pasta, and similar dry products for which a natural loss of moisture occurs and a net weight limit is set for sale. Similarly, some products that gain moisture have a textural limit at which they become too soft, such as potato chips, other dried or fried snacks, and crackers.
Temperature Induced Texture Changes
Temperature fluctuations per se can affect physical modes of deterioration. For example, the continuous rise and fall of temperature around a phase change point leads to melting of fat and the subsequent degradation of quality of some candies and formulated foods.
Staling
Staling is a mode of deterioration important in processed wheat flour products such as bread and cakes. The reaction is a crystallization ion of amylopectin, one of the major starches present in wheat flour. The rate is increased as temperature decreases, which is opposite to the chemical, enzymatic, and microbial reactions discussed earlier. Thus, to prevent staling, the food must not be refrigerated. However, this can result in other reactions causing loss of shelf life.
Induced Textural Changes
Both lipid oxidation and non-enzymatic browning result in degradation of proteins, which leads to toughening and loss of shelf life.
Before harvest and slaughter, plant and animal foods are subject to a myriad of microbiological diseases including viruses, molds, yeasts, and bacteria. In addition, some foods before harvest can be attacked and diseased or eaten by insects, birds, and rodents. For plants, competition by weeds can result in poor yield. To prevent or control this, one form of processing is the use of chemical or physical means of control or prevention. The use of pesticides, and herbicides are examples of chemical control. Another method of chemical control is the use of drugs such as antibiotics to prevent disease in animals prior to slaughter. Weeding by machine is a physical means of control. These modes of deterioration are not generally considered about shelf life or open dating. However, if the food is subjected to damage, its initial quality will be less. Processing does not make low quality foods better, and overall shelf life will be less after slaughter or harvest than with undamaged foods.
Senescence
Once a fruit, vegetable, cereal grain, or animal product is slaughtered, it is separated from its source of nutrients and water. However, since it is still a viable living system, the enzymes present continue to operate and utilize the available carbohydrate and nutrient stores. For fruits, this process can be of benefit because they can repair post harvest damages, and more important, fruits can be picked prior to optimum maturity, transported long distances to the marketplace and home, and then develop into a high quality product.
For all foods, however, eventually enzymatic biochemical processes occurring post harvest lead to degradation, including loss of color, flavor, nutrients, and texture. In addition, the breakdown products produced damage the tissue so that the foods become subject to microbiological attack with subsequent more rapid decay. To prevent this mode of deterioration, three major processing methods can be used: (1) lowering of temperature slows the reaction; (2) raising the temperature denatures the enzymes and makes them inactive; and (3) removal or binding of water reduce availability (or water activity), which reduces the ability of the enzymes to operate.
Microbiological Disease
Microorganisms constitute a major mechanism by which many foods, especially fresh ones, lose their quality. This is because microbes are ubiquitous in the environment, and can grow rapidly. After a food is harvested or slaughtered, it loses some degree of its ability to fight off microbial attack. If it is physically damaged, then it becomes more susceptible to attack. Bruising, cutting, and trimming constitute such damage. Microbes can grow rapidly on foods (starting with one microbe which divides every 10 min, with sufficient available nutrients, in five hours there would be over one billion microbes present). The basic principle of preservation is to control or destroy them. Much the same controls, are employed as those used for enzymes:
(1) Lower temperature to slow growth.
(2) Raise temperature to kill them.
(3) Remove or bind water to slow or prevent their growth.
(4) Lower pH to slow or stop their growth by adding-acid or fermentation.
(5) Control O2 or CO2 level to control population.
(6) Manipulate food composition to remove nutrients needed by the microbes.
Because in some cases the above methods change the food into a form not desirable by the consumer, chemical means of preservation can be used. These chemicals are used to slow growth or kill the organisms. At the level of use, the chemicals should have no ill effect on the consumer. Examples are the use of calcium propionate in bread and sodium benzoate in some soft drinks.
Knowledge of the rate of growth of microbes as a function of the environmental conditions of the food is very important in the prediction of shelf-life and, thus, the open dating of some foods such as: fresh and ground meats and fresh poultry; fresh fish; dairy products such as milk. Cheese and yogurt; cured meats such as hot dogs, bacon, and bologna: pasteurized fruit drinks; fruits and vegetables; and whole grains.
A second and more serious problem with microorganisms is the fact that some are pathogenic to humans, i.e., they either cause infection when ingested or result in the production of chemicals in the food, which are toxic to humans. Most food processes are designed to guard against contamination with pathogens and the subsequent growth of these pathogens after processing, or as important, to treat the food in such n way as to destroy any potentially harmful microbes that might be inadvertently present in the food. For example, fermentation of foods with useful microbes results in alcohol or acid production. The acid and alcohol prevent the growth of pathogens.
Chemical Deterioration
During the processing of foods, tissue damage occurs which causes the release of various food chemical constituents into the cellular fluid environment. These chemicals can then react with each other or with external factors to lead to deterioration of the food and result in a shortening of the shelf life. Many different reactions can occur which lead to quality and nutrient loss. The major ones are classified below.
Enzymatic
The normal post-harvest enzymatic reactions can lead to a loss in food quality and shelf life. In addition, destruction of cell tissues releases enzymes, which can lead to further deterioration. This reaction is usually very rapid at room temperature, but is controlled in the natural state. Once the food is handled, deterioration starts. Enzymatic decay also occurs in the frozen state unless the enzymes are previously denatured by blanching. Enzymatic reactions also lead to the major mode of deterioration of many refrigerated dough. Unfortunately, heat treatment to denature the enzymes results in loss results in loss of dough functionality. Control of the enzymatic reactions is the same as was discussed for senescence. Knowledge of the rate of these reactions as a function of environmental conditions is very important in prediction of shelf life for open dating. The major environmental factors are oxygen, water, pH, and temperature. Other enzymatic degradations include color losses and vitamin tosses such as for vitamin C.
Lipid Oxidation
Many foods contain unsaturated fats, which are important in the nutrition of humans. Unfortunately, these fats are subject to direct attack by oxygen through an auto catalytic free radical mechanism. This results in the production of rancid off-flavors, which make the food undesirable to consume. Very little fat has to oxidize for the consumer to detect rancidity and reject the food. Unfortunately, the food will still be very nutritious. The free radicals and peroxides produced in this process can react and blench pigments, such as occurs in dried vegetables, and can destroy vitamins C, E, and A. They can also result in protein degradation, making it of poorer quality, as can happen in whole dry milk; can cause darkening of the fat as happens in deep fat frying; and produce toxic substances which have been implicated in some animal studies as potential carcinogens.
Knowledge of the rate of lipid oxidation is important in foods where it be the principal mode of deterioration, for example:
(1) Fried snacks,
(2) Nuts,
(3) Dried meats/vegetables/fish/poultry,
(4) Cereals,
(5) Wheat germ,
(6) Frozen vegetables/meats/fish/poultry,
(7) Some dairy products,
(8) Semi-moist meat products,
(9) Pre cooked refrigerated meats and fish,
(10) Cured meat and fish, coffee, cooking and salad oils, margarine, spices, and dried vegetables such as potatoes and carrots.
Non Enzymatic Browning (NEB)
Non Enzymatic Browning (NEB) is another major chemical reaction leading to a loss of quality and nutritional value. This reaction is the result of reactions between reducing compounds (such as glucose, fructose and lactose) and proteins or amino acids. Browning can also occur as the result of heating sugars to very high temperatures or through the oxidation of vitamin C. In certain cases the reaction is desirable, such as in the toasting of the bread, the crust formed in roasting meats, malting of barley for beer and spirits manufacture, and the production of syrups, molasses, and caramel candies.
Other Chemical Reactions
Other chemical reactions that can lead to food degradation include the thermal destruction of vitamins such as A, B, and C, the effect of light an pigments such as occurs in the browning of meat and bleaching of chlorophyll, the direct oxidation of vitamin C, the effect of light on riboflavin, and the direct oxidation of carotenoid pigments and the loss of flavor through some mechanism. In ever case the effect of temperature, oxygen level, moisture content, and light must be known for the rate of the reaction to be predicted and the time to reach end of shelf life measured. Of importance in all these reactions is a decision as to what extent of degradation is considered to be the end of shelf life.
Physical Degradation
Physical damage can also lead to loss of shelf life. The types of physical damage can be classified into the following categories.
Physical Bruising/Crushing
This mode of deterioration is related to physical abuse of in food harvest, processing, and distribution. It is particularly important to fruits and vegetables, since physical abuse leads to microbial attack and decay. Packaging to prevent abuse is key to long shelf life. With dry materials such as chips, crushing can lead to unacceptability based on consumer desires.
Wilting
Fresh leafy and tuber vegetables can deteriorate if subjected to low relative humidity, losing moisture to their surroundings. This results in loss of crispness and an increased rate of senescence reactions with subsequent quality and nutrient losses. Proper knowledge of the rate of moisture loss for various packaging materials and the maximum allowable moisture loss can be used as one means of setting open dates for fresh produce.
Moisture Loss/Gain
With some food products such as candy, semi moist pet foods, cakes and bread, moisture loss leads to an increase in hardening. If a limit of hardness is known to be unacceptable then predictions to reach this level based on equations which describe the moisture change with time, can be used as one method of prediction of end of shelf life. From this, the open date for best quality can be set. These same equations can be used to predict the moisture loss of flour, pasta, and similar dry products for which a natural loss of moisture occurs and a net weight limit is set for sale. Similarly, some products that gain moisture have a textural limit at which they become too soft, such as potato chips, other dried or fried snacks, and crackers.
Temperature Induced Texture Changes
Temperature fluctuations per se can affect physical modes of deterioration. For example, the continuous rise and fall of temperature around a phase change point leads to melting of fat and the subsequent degradation of quality of some candies and formulated foods.
Staling
Staling is a mode of deterioration important in processed wheat flour products such as bread and cakes. The reaction is a crystallization ion of amylopectin, one of the major starches present in wheat flour. The rate is increased as temperature decreases, which is opposite to the chemical, enzymatic, and microbial reactions discussed earlier. Thus, to prevent staling, the food must not be refrigerated. However, this can result in other reactions causing loss of shelf life.
Induced Textural Changes
Both lipid oxidation and non-enzymatic browning result in degradation of proteins, which leads to toughening and loss of shelf life.
Saturday, August 14, 2010
Hygienic Design of Fish Processing Plants
Introduction
Hygienic design of fish and food handling areas is concerned primarily with prevention of microbial hazards, but should also include consideration of occupation safety, convenience of handling or even aesthetics. This article will deal mainly with the reasons behind the hygienic design requirements, stressing the particular hazards involved and their control. In terms of microbiology, this includes preventing contamination of the product and limiting multiplication and spread of microorganisms in the environment.
Food including fish has to pass through many operations as they are handled from the very first steps of harvesting or primary production to the final stages of distribution, retailing and handling in food service establishments or in the home. Hygienic aspects of the sign of food operating areas have to be considered in respect of:
a. Production, harvesting and slaughter;
b. Incoming raw materials;
c. Processing;
d. Storage;
e. Distribution, handling and use
- In wholesale markets and retail premises;
- In food service establishments;
- In kitchens.
In each of these categories, great variability exists in the size and the extent of handling (e.g. a small fishing boat compared with a large factory vessel; a rural market in a developing region compared with a supermarket in an industrialized region). Accordingly, the hygienic requirements for the design of a food handling area may vary considerably even when the same foods are handled. All design factors commonly listed in legislation and codes of practice are not equally important in respect of hygiene. The more important factors include facilities for water supply, waste-disposal and cooling and cold storage facilities. Of less importance with respect to microbiological hazards are buildings (including floors, walls and storage rooms), ventilation, factory location, and clothes changing facilities, lighting, and roadways. However, all requirements need be considered in order to meet national and/or international requirements.
Some General Considerations and Definitions
For a better understanding of the problems involved it is necessary to consider briefly a few terms which are often used, particularly in the Codes of Hygienic Practice.
‘Designed in a hygienic way’
In microbiological terms, this means the creation of environmental conditions, which are not conducive to the growth of microorganisms. Thus, no facilities may be deemed ‘hygienic’ that offers an opportunity for the accumulation of organic matter and/or moisture (e.g. edges, nooks, crevices, fissures, breaks, cracks and scratches or absorbent materials which are resistant to cleaning).
‘Easy to clean’
This is closely related to the term ‘hygienic’. It refers to the arrangement of construction elements with an area (e.g. surfaces of the ceilings or walls, arrangement of pipes leading from sinks or tanks to the wall or to the ground). Dirt, soil, and moisture cannot be easily removed from floors unless joints between walls and floors are covered. ‘Easy to clean’ describes any design, which will minimize the efforts required for thorough and effective sanitation operations.
‘Surface’
In respect of the handling of fish, it has proved useful to distinguish three categories of surfaces encountered within a processing facility
a. Surfaces of materials that are intended to are exposed to foods (e.g. silos and storage bins). The risk of contamination of foods is high.
b. Surfaces of materials not intended to be exposed to foods, but which may accidentally have such contact (e.g. walls in a processing area). The risk of contamination of foods is low.
c. Surfaces of materials not intended to be exposed to foods (e.g. floors and ceilings in processing areas). These are of concern primarily for aesthetic reasons and for safety of personnel but need to be cleanable and kept clean. The risk of contamination of food is low.
‘Clean and unclean’
These terms cannot be defined precisely because their meanings are relatives and vary with the intended purpose and with the products. In fact, there are several degrees of cleanliness. The requirements for cleanliness for storing raw agricultural products are quite different from those in a filling section of Ultra High Temperature milk in dairy plant.
Location and Surrounding Area
In the design phase of fish harvesting and processing areas, several aspects are of particular concern in respect of hygiene. These may include:
a. Proximity of potential source of contamination;
b. Sufficiency and quality of water supply;
c. Waste water removal;
d. Adequacy of power supply, particularly in emergencies;
e. Availability of transportation.
Climate can have an important bearing on design criteria. For example, average, minimum and maximum annual temperatures and relative humidifies must be taken into account in the design of facilities and may require different approaches in hot humidity climates than in cooler, drier regions.
Potential locations for fish plants should be surveyed to assess possible hygienic hazards, e.g. nearby dumping areas may contribute to atmospheric pollution and harbor vermin. Fish handling establishments should not be located close to bone yards, stables or other places where live animals are held or to establishments handling skins and hides such as tanneries, waste disposal sites and other enterprises which deal with highly contaminated material.
To prevent accumulation of water and the generation of dust, roadways and yards serving the establishment should have a hard, and where practicable, paved surface, and adequate drainage.
Hygiene and the Design of Facilities
The micro flora of processing plants is composed of microorganisms that gain entry from the air and water and, more importantly, those brought in by animals, raw materials, dust, dirt, and people. Equipment may also serve as vehicles of contamination.
The following general principles can be summarized for the hygienic design of fish handling areas:
a. Arrangement of Rooms, Areas and Processes within Establishments
- The plant and surrounding area should be such as can be kept reasonably free from objectionable odors, smoke, dust, or other contamination. The building should be sufficient in size without crowding of equipment or personnel, well constructed and kept in good repair. They should be of such design and construction to protect against the entrance and harboring of insects, birds, or other vermin, and to permit ready and adequate cleaning.
- Fish processing plants should be designed and equipped so that all handling and processing operations can be carried out efficiently, and all materials and products can pass from one stage of processing to the next in an orderly manner and with minimum delay.
- Areas where fish are received or stored should be so separated from areas in which final product preparation or packaging is conducted as to prevent contamination of the finished product.
- Separate and adequate storage should be provided for wood, saw dust or similar materials used in smoking of fish.
- Separate and adequate facilities should be provided for drying fish.
- Salt and other ingredients used in the curing or processing of fish or fish products should be stored where appropriate in a dry state and in a manner to prevent their contamination.
- Storage facilities should be available for the proper dry storage of packaging materials.
- If poisonous or harmful materials, including cleaning compounds, disinfectants and pesticides are stored, they should be kept in a separate room designed or marked specifically for this purpose.
b. Structural Components of Establishments
- Floors should be hard surfaced, non-absorbent and adequately drained.
- Internal walls should be smooth, waterproof, resistant to fracture, light colored and readily cleanable.
- Ceiling should be so designed, constructed, and finished as to prevent accumulation of dirt and minimize condensation, mould development, flaking, and should be easy to clean.
- Windowsills should be kept to a minimize size, be sloped inward at least 45 degrees and be at least one meter from the floor.
- All doors through which fish or their products are moved should be sufficiently wide, well constructed of a suitable materials and should be of a self-closing type.
- Stairs, lift cages and auxiliary structures should be so situated and constructed as not to cause contamination to fish
c. Control of environmental
- Premises should be well ventilated to prevent excessive heat, condensation, and contamination with obnoxious odor, dust, vapor, or smoke.
- A minimum illumination of 220 lux (20 foot candles) in general working areas and not less than 540 lux (50 foot candles) at points requiring close examination of the product should be provided and should not alter colors.
- An ample supply of cold and hot potable water and/or clean sea water under adequate pressure should be available at numerous points throughout the premises at all times during the working ours.
- When in-pant chlorination of water is used, the residual content of free chlorine should be maintained at no more than the minimum effective level for the use intended.
- Ice should be made from potable water or clean seawater and should be manufactured, handled and stored to protect it from contamination.
- Proper facilities for washing and disinfection of equipment should be provided.
- Drains should be of an adequate size, suitable type, equipped with traps and with removable grating to permit cleaning.
- A separate refuse room or other equally adequate offal storage facilities should be provided on the premises.
- Staff amenities such as lunchrooms and changing rooms or rooms containing shower or washing facilities should be provided.
- Adequate and conveniently located toilet facilities should be provided.
- Facilities should be available in the processing areas for employees to wash and dry their hands and for disinfection.
Hygienic design of fish and food handling areas is concerned primarily with prevention of microbial hazards, but should also include consideration of occupation safety, convenience of handling or even aesthetics. This article will deal mainly with the reasons behind the hygienic design requirements, stressing the particular hazards involved and their control. In terms of microbiology, this includes preventing contamination of the product and limiting multiplication and spread of microorganisms in the environment.
Food including fish has to pass through many operations as they are handled from the very first steps of harvesting or primary production to the final stages of distribution, retailing and handling in food service establishments or in the home. Hygienic aspects of the sign of food operating areas have to be considered in respect of:
a. Production, harvesting and slaughter;
b. Incoming raw materials;
c. Processing;
d. Storage;
e. Distribution, handling and use
- In wholesale markets and retail premises;
- In food service establishments;
- In kitchens.
In each of these categories, great variability exists in the size and the extent of handling (e.g. a small fishing boat compared with a large factory vessel; a rural market in a developing region compared with a supermarket in an industrialized region). Accordingly, the hygienic requirements for the design of a food handling area may vary considerably even when the same foods are handled. All design factors commonly listed in legislation and codes of practice are not equally important in respect of hygiene. The more important factors include facilities for water supply, waste-disposal and cooling and cold storage facilities. Of less importance with respect to microbiological hazards are buildings (including floors, walls and storage rooms), ventilation, factory location, and clothes changing facilities, lighting, and roadways. However, all requirements need be considered in order to meet national and/or international requirements.
Some General Considerations and Definitions
For a better understanding of the problems involved it is necessary to consider briefly a few terms which are often used, particularly in the Codes of Hygienic Practice.
‘Designed in a hygienic way’
In microbiological terms, this means the creation of environmental conditions, which are not conducive to the growth of microorganisms. Thus, no facilities may be deemed ‘hygienic’ that offers an opportunity for the accumulation of organic matter and/or moisture (e.g. edges, nooks, crevices, fissures, breaks, cracks and scratches or absorbent materials which are resistant to cleaning).
‘Easy to clean’
This is closely related to the term ‘hygienic’. It refers to the arrangement of construction elements with an area (e.g. surfaces of the ceilings or walls, arrangement of pipes leading from sinks or tanks to the wall or to the ground). Dirt, soil, and moisture cannot be easily removed from floors unless joints between walls and floors are covered. ‘Easy to clean’ describes any design, which will minimize the efforts required for thorough and effective sanitation operations.
‘Surface’
In respect of the handling of fish, it has proved useful to distinguish three categories of surfaces encountered within a processing facility
a. Surfaces of materials that are intended to are exposed to foods (e.g. silos and storage bins). The risk of contamination of foods is high.
b. Surfaces of materials not intended to be exposed to foods, but which may accidentally have such contact (e.g. walls in a processing area). The risk of contamination of foods is low.
c. Surfaces of materials not intended to be exposed to foods (e.g. floors and ceilings in processing areas). These are of concern primarily for aesthetic reasons and for safety of personnel but need to be cleanable and kept clean. The risk of contamination of food is low.
‘Clean and unclean’
These terms cannot be defined precisely because their meanings are relatives and vary with the intended purpose and with the products. In fact, there are several degrees of cleanliness. The requirements for cleanliness for storing raw agricultural products are quite different from those in a filling section of Ultra High Temperature milk in dairy plant.
Location and Surrounding Area
In the design phase of fish harvesting and processing areas, several aspects are of particular concern in respect of hygiene. These may include:
a. Proximity of potential source of contamination;
b. Sufficiency and quality of water supply;
c. Waste water removal;
d. Adequacy of power supply, particularly in emergencies;
e. Availability of transportation.
Climate can have an important bearing on design criteria. For example, average, minimum and maximum annual temperatures and relative humidifies must be taken into account in the design of facilities and may require different approaches in hot humidity climates than in cooler, drier regions.
Potential locations for fish plants should be surveyed to assess possible hygienic hazards, e.g. nearby dumping areas may contribute to atmospheric pollution and harbor vermin. Fish handling establishments should not be located close to bone yards, stables or other places where live animals are held or to establishments handling skins and hides such as tanneries, waste disposal sites and other enterprises which deal with highly contaminated material.
To prevent accumulation of water and the generation of dust, roadways and yards serving the establishment should have a hard, and where practicable, paved surface, and adequate drainage.
Hygiene and the Design of Facilities
The micro flora of processing plants is composed of microorganisms that gain entry from the air and water and, more importantly, those brought in by animals, raw materials, dust, dirt, and people. Equipment may also serve as vehicles of contamination.
The following general principles can be summarized for the hygienic design of fish handling areas:
a. Arrangement of Rooms, Areas and Processes within Establishments
- The plant and surrounding area should be such as can be kept reasonably free from objectionable odors, smoke, dust, or other contamination. The building should be sufficient in size without crowding of equipment or personnel, well constructed and kept in good repair. They should be of such design and construction to protect against the entrance and harboring of insects, birds, or other vermin, and to permit ready and adequate cleaning.
- Fish processing plants should be designed and equipped so that all handling and processing operations can be carried out efficiently, and all materials and products can pass from one stage of processing to the next in an orderly manner and with minimum delay.
- Areas where fish are received or stored should be so separated from areas in which final product preparation or packaging is conducted as to prevent contamination of the finished product.
- Separate and adequate storage should be provided for wood, saw dust or similar materials used in smoking of fish.
- Separate and adequate facilities should be provided for drying fish.
- Salt and other ingredients used in the curing or processing of fish or fish products should be stored where appropriate in a dry state and in a manner to prevent their contamination.
- Storage facilities should be available for the proper dry storage of packaging materials.
- If poisonous or harmful materials, including cleaning compounds, disinfectants and pesticides are stored, they should be kept in a separate room designed or marked specifically for this purpose.
b. Structural Components of Establishments
- Floors should be hard surfaced, non-absorbent and adequately drained.
- Internal walls should be smooth, waterproof, resistant to fracture, light colored and readily cleanable.
- Ceiling should be so designed, constructed, and finished as to prevent accumulation of dirt and minimize condensation, mould development, flaking, and should be easy to clean.
- Windowsills should be kept to a minimize size, be sloped inward at least 45 degrees and be at least one meter from the floor.
- All doors through which fish or their products are moved should be sufficiently wide, well constructed of a suitable materials and should be of a self-closing type.
- Stairs, lift cages and auxiliary structures should be so situated and constructed as not to cause contamination to fish
c. Control of environmental
- Premises should be well ventilated to prevent excessive heat, condensation, and contamination with obnoxious odor, dust, vapor, or smoke.
- A minimum illumination of 220 lux (20 foot candles) in general working areas and not less than 540 lux (50 foot candles) at points requiring close examination of the product should be provided and should not alter colors.
- An ample supply of cold and hot potable water and/or clean sea water under adequate pressure should be available at numerous points throughout the premises at all times during the working ours.
- When in-pant chlorination of water is used, the residual content of free chlorine should be maintained at no more than the minimum effective level for the use intended.
- Ice should be made from potable water or clean seawater and should be manufactured, handled and stored to protect it from contamination.
- Proper facilities for washing and disinfection of equipment should be provided.
- Drains should be of an adequate size, suitable type, equipped with traps and with removable grating to permit cleaning.
- A separate refuse room or other equally adequate offal storage facilities should be provided on the premises.
- Staff amenities such as lunchrooms and changing rooms or rooms containing shower or washing facilities should be provided.
- Adequate and conveniently located toilet facilities should be provided.
- Facilities should be available in the processing areas for employees to wash and dry their hands and for disinfection.
Tuesday, August 10, 2010
Hazard Analysis and Assignment of Risk Categories
Overview
Hazard analysis consists of a system evaluation of a specific food and its raw materials or ingredients to determine the risk from biological (primarily infectious or toxin producing food borne illness microorganism), chemical, and physical hazards. The hazard analysis is a step procedure: hazard analysis and assignment of risk categories.
The first step is to rank the food and its raw materials or ingredients according to six hazard characteristics (A-F). A food is scored by using a plus if the food has the characteristic, and a zero (0), if it does not exhibit the characteristic. The six characteristics ranking system is applied for microbiological, chemical and physical hazard ranking, although the characteristics are somewhat different for microbiological and chemical/physical hazard as described later.
The second step is to assign risk categories (VI) to the food and its raw materials and ingredients based on the results of ranking by hazard characteristics. In addition, note that whenever there is a plus for hazard characteristics A (special class that applies to food designated for high risk population), the resulting hazard categories is always VI, even though other hazard characteristics B-F may or may not be a plus.
Several preliminary steps are needed before conducting the hazard analysis. These include developing a working description of the product, listing the raw materials and ingredients required for producing the product, and preparation of a diagram of the complete food production sequence. The listing of raw materials and ingredients is the starting point for the hazard analysis. If the specific mode of preservation for an ingredient is not known (raw, frozen, canned, etc), the ingredient may be assessed for each type of preservation technique that may be utilized in preserving the ingredient.
Microbiological Hazard Characteristics Ranking
Several minor changes in hazard F, to differentiate ranking for consumer products and raw materials and ingredients as received by the processor before any manufacturing steps. As indicated earlier, rank the product and its raw materials and ingredients exhibit the characteristic and a zero when they do not.
A sensitive ingredient is defined as any ingredient historically associated with a known microbiological hazard. The term ingredient normally also applies to raw materials. Sensitive ingredient was coined for microbiological hazards (infectious agents and their toxins) but it is also now used for ingredients and raw materials that are historically associated with known chemical or physical hazards.
The original list of microbiologically sensitive foods was based on the potential presence of the Salmonella species. Now any type of hazardous microorganism may cause a food to be sensitive, and the list of sensitive foods has grown, particularly with the recognition that Listeria monocytogenes is a known threat in many foods. If there is a question as to whether foods sensitive, it should considered sensitive until more information is available for purposes of clarifying its status.
Compounded ingredients may be considered sensitive if they are combinations of sensitive and non-sensitive ingredients. For example, a fat coated on milk powder, or compounded cheese flavor coated on starch. It is best to list all components of a blended materials to determine if the blend contains a sensitive ingredient and also determine if it has received a controlled processing step that destroy hazardous microorganisms. In some cases, it is important to determine if microbiological toxins may also be present in a processed food if it is to be used as an ingredients (e.g. heat stable staphylococcus enterotoxin in canned mushroom).
Many raw materials and ingredients are not considered microbiologically sensitive even though they may occasionally be contaminated with hazardous microorganism.
Chemical and Physical Hazard Risk Assessment Procedures
Hazard characteristics for chemical and physical agents were developed in 1990 for use in the ESCA genetics Corporation training course, “A Practical Application of HACCP,” and were recently published. They are designed so that both chemical and physical hazards in food may be assessed by using the same six hazard characteristics.
Generally, hazard analysis for chemical and physical hazard is conducted like the procedure for microbiological hazards provided in the NACMCF guide. Although the six hazard characteristics are somewhat different, the same plus (+) and zero (0) scoring system and hazard assignment procedure are used.
THE ROLE OF THE SUPERVISOR
DEFINITION OF A SUPERVISOR
A supervisor is any person who is given the authority and responsibility for planning and controlling the work of a group by close contact. Broadly speaking, this definition means that a supervisor may be delegated with the authority to engage, transfer, suspend, reprimand or dismiss an employee under his control. He may deal with grievances and take appropriate action. He is responsible for the quantity and quality of the output.
In fact, a supervisor is anyone who directs the work of other by giving instructions in production or other functional areas, by coordinating specialist departments and recommending courses of action to management.
THE MODERN SUPERVISOR
The modern supervisor must be educated, technically well trained and be an efficient leader of people to meet the competitive demands of high quality output at minimum cost.
An efficient management program requires a well trained supervisor who understands people, supervises people effectively, encourages teamwork and cooperation, develops and trains people, generates support from other Supervisors, manages time and technical aspects of the work effectively.
SUPERVISION AND MANAGEMENT
Supervision implies operating at close range by actually overseeing or controlling on the shop floor, dealing with situations on tile spot as they arise, whereas management implies controlling remotely by using other administrative means.
Supervision and management naturally overlap in practice, partly from necessity, where managers show close personal interest in order to achieve cooperation, and partly due to lack of management training.
The supervisor is concerned with day-to-day running of the section, which will entail a certain amount of attention to detail depending upon the size of the section. If the section is large, the supervisor will need to master the art of delegation, pass on the minor tasks to his subordinates, thus giving himself more time to plan and control the work effectively.
The manager is concerned with the mapping out of future corporate policies, explanation programs, new products, new markets and other business strategies, leaving the detail and less important tasks to the subordinates.
BASIC ELEMENTS OF SUPERVISION
What is Supervision? Supervision is defined as the management of a process, a worker or a project.
The basic elements as follows:
1. Building and maintaining an efficient organization;
2. Creating and maintaining an effective work force;
3. Controlling
The supervisor will improve his performance considerably by using the technique of each of the basic elements of supervision to supplement his technical knowledge. The ability to apply the right principles at the right time demands something more than knowledge alone. The three elements of supervision must interact closely although they are considered independently. For example, no decision should be made on the fact and theories alone; the human factor must also be given due consideration. Training and a balanced outlook are essential for successful of supervisory techniques.
Building and Maintaining an Efficient Organization
The supervisor must be able to appreciate the significance of the organization structure and reorganize the relationships within it, in order to improve coordination with other groups in the organization.
Within the sphere of organization, the supervisor should possess knowledge of the general industrial background, the work of management and the supervisor’s position and role in the management team.
A summary of duties concerning the first element of supervision is as follows:
l. Organization planning to achieve objectives.
2. Keeping subordinates informed and conscious of objectives.
3. Establishing and maintaining organization relationships among all subordinates.
4. Explaining, directing and controlling all the activities of the section and in turn of individuals.
5. Ensuring that the group is an integral part of the organization.
6. Recommending changes in organization where necessary.
7. Using specialists effectively.
8. Coordinating all activities within the group to achieve the objective.
Creating and Maintaining an Effective Work Force
Any aspect of supervision has some bearing on employees and their attitude towards work. The effective supervisor must be able to understand and motivate individuals, develop and maintain good communication and pay close attention to an employee’s opinion and behavior.
The scope of duties in this second element of supervision is:
1. Fostering good working relationship.
Mediating between workers and management, cooperating with fellow supervisors, and consulting shop floor workers.
2. Promoting good communication. Submitting production reports to management; making special reports where necessary, and attending meetings as directed.
3. Providing information.
Interpreting company policies and instructions and informing employees of their meaning to avoid ambiguity.
4. Promoting and maintaining high morale,
Keeping in constant touch with workers; dealing with grievances as they arise; operating a suggestion scheme and encouraging participation.
5. Maintaining general discipline and conducting disciplinary interviews.
6. Keeping up to date on wage systems in the company and rating employees accurately in their appraisals.
7. Interviewing candidates and orienting new employees.
8. Training new and transferred employees in their jobs.
9. Liaising with the Human Resource Officer on questions of transfers, promotions and termination.
Controlling the Work
Controlling the work covers a wide field, which begins at the planning stage of production and ends with the finished product. The field of control includes:
1. Division and delegating of responsibility to individuals.
2. Decision on the work content.
3. Budgeted costs of performing the work.
4. Regulation of work performance by such factors as human relations and motivation; cost reduction and progress.
5. Quality control.
The supervisor's duties with regard to control are as follows:
1. Planning production and setting up procedures, which will include routing, scheduling, job dispatching and follow up.
2. Maintaining plant and equipment.
3. Using work-study technique and procedures to develop the department.
4. Achieving and maintaining quality and keeping statistical records on quality control.
5. Recording and ensuring adequate supplies of materials in accordance with store and materials control guidelines.
6. Checking waste and establishing cost reduction control where necessary.
7. Keeping adequate records and controlling costs as budgeted.
8. Promoting safety and a healthy working environment.
THE RESPONSIBILITY OF THE SUPERVISOR
Responsibilities for most supervisors encompass the following broad areas:
1. Responsibilities to management
Supervisors must dedicate themselves to the goals, plans and policies of the organization. These are laid down by higher management. It is the primary task of supervisors to serve as a link for management to ensure that these are carried out by the employees they supervise.
2. Responsibilities to employees
Employee’s expert their supervisors to provide direction and training; to protect them from unfair treatment and to see that the workplace is clean, safe, uncluttered, properly equipped, well lighted and adequately ventilated.
3. Responsibilities to staff specialist
The relationship between supervisor and the staff department is one of mutual support. The staff development is charged with providing supervisors with guidance and help as well as prescriptions to be followed and forms to be completed. Supervisors, in turn help the staff department by making good use of their advice and services by conforming to their requests.
4. Responsibilities to other supervisors
Teamwork is essential in the supervisory ranks. The goals and activities of one department must harmonize with those of other departments. This often requires the sacrifice of an immediate target for the greater good of the organization.
5. Responsibilities to union
If there is a union in the organization, union and management views are often in conflict and supervisor and shop workers arc often deadlocked. It is part of the supervisor's responsibilities to keep these relationships objective, neither to "give away" the department nor to yield responsibilities for the welfare of the organization and its employees.
TYPES OF SUPERVISORY SKILLS REQUIRED
To perform the supervisory function well, a supervisor needs the following skills:
2. Administrative skills Knowledge of the entire organization and how it is coordinated, its information and records system, its ability to plan and control work. These are related ideas, plans, and directives. The ability to see organization as a whole and to understand the overall effect of several departments.
3. Human relation skills Knowledge of human behavior, the ability to work effectively with individuals and groups-peers and supervisors as well as subordinates.
4. Conceptual skillThese are related ideas, plans, and directives. The ability to see organization as a whole and to understand the overall effect of several departments.
In order to be effective, a supervisor needs to pay as much attention to human relations as to technical and administrative matters. He has to spend as much time maintaining group cohesiveness and morale as he pushes for productivity or task accomplishment. Thus, a supervisor who focuses on job demands and without showing interest in the welfare and development of his subordinates does not get the results he is looking for. Conversely, the supervisor who bends over backward to make-work easy for his employees does not get good result either. It takes a balance between the two approaches.
Overview of Biological, Chemical and Physical Hazard
Introduction
HACCP is a systematic approach to be used in food production as a means to ensure food safety. The first step requires a hazard analysis, an assessment of risks associated with all aspects of food production from growing to consumption. However, before one can assess the risk, a working knowledge of potential hazard must be obtained. A hazard is defined by the National Advisory Committee on Microbiological Criteria for Foods (NACMCF) as any biological, chemical or physical property that may cause an unacceptable consumer health risk. Thus, by definition one must be concerned with three classes of hazard, biological, chemical, and physical.
This article provides a generalized background of the potential hazard associated with foods. Appropriate reference materials on food hazards have been included. A number of textbooks are available on the subject of hazards in foods.
Biological Hazards
The first hazards category, biological or microbiological, can be further divided into three types: bacterial, viral, and parasitic (protozoa and worms). Many HACCP programs are designed specifically around the microbiological hazards. HACCP programs address this food safety problem by assisting in the production of safe wholesome foods.
When developing a HACCP programs, the food grower or processor should have three basic aims with regard to biological hazards: (1) destroy, eliminate, or reduce the hazard; (2) prevent recontamination (3) inhibit growth and toxin production. Preventive measures should be taken to achieve these goals.
Microorganisms can be destroyed or eliminate by thermal processing, freezing and drying. After the microorganism has been eliminated, measures to prevent recontamination should be taken. Finally, if hazard cannot be totally eliminated from the food, microbial growth and toxin production must be inhibited. Growth can be inhibited through the intrinsic of the food, such as pH and water activity (aw), or by the addition of salt or other preservatives. Condition under which the food is packaged (aerobic or anaerobic) and storage temperatures (refrigeration or freezing) can also used to inhibit growth.
Bacterial Hazards
Bacterial hazards can result either in foodborne infections or intoxications. A foodborne infection is caused by ingesting a number of pathogenic microorganisms sufficient to cause infection, and the reaction of tissues to their presence, multiplication, or elaboration of toxins. A foodborne intoxication is caused by the ingestion of preformed toxins produced and excreted by certain bacteria when they multiply in foods.
The following summary discusses the notable characteristics of the various foodborne bacterial pathogens of concern to the food industry and their relationship to the developing of a HACCP program. The natural incidence and the severity of disease caused by these bacteria, along with the general conditions required for their control represent a cross-section of challenges for HACCP programs. If these organisms are controlled, numerous other pathogens may be similarly controlled.
Clostridium botulinum
Clostridium botulinum, the causative agent of botulism (foodborne intoxication), is an anaerobic, spore-forming rod that produces a potent neurotoxin. Its notable characteristics are its heat-resistant spores and their widespread distribution. Some strains of C. botulinum are psychotropic. The spores survive most thermal processes except those specially designed to eliminate them. If such a process is not used, one must assume that spores are present in the food. If the food is to be packaged in an anaerobic or reduce oxygen atmosphere, measures to inhibit the growth and toxin production by the organism are necessary. C. botulinum growth can be controlled by one or a combination of the following conditions : pH < 4.6; aw <= 0.94; 5-10% salt concentration; nitrite and salt combination (e.g. cured meats); other preservatives, temperature control (freezing/refrigeration) and biocontrol (e.g. inoculation of product with lactic acid bacteria). Sole reliance on refrigeration to ensure safety is risky. Botulinum toxin produced is one of the most potent substances known but is relatively heat labile (destroyed by boiling for 10 minutes). Reliance on final cooking the consumer to destroy the toxin is extremely risky.
Listeria monocytogenes
Listeria monocytogenes is a hazardous foodborne microorganism of relatively recent concern. It is ubiquitous in nature and is commonly found in food processing environments. It causes listerosis, a severe and often fatal illness, to which certain populations (e.g. pregnant mother, newborn, immunocomprised individuals, transplant recipients) may be susceptible. Fatality rates with the more severe forms of listerosis can be as high as 70% for those untreated, but generally are between 25 and 35%. The organism is psychotropic and can grow at refrigeration temperatures. Its widespread distribution and its ability to multiply at refrigeration temperatures and cause severe illness makes it a hazard of particular concern to the food industry and regulatory agencies. HACCP programs should attempt to destroy, eliminate or reduce this hazard and prevent the opportunity for subsequent recontamination.
Salmonella
Salmonella species can be found on most raw foods of animal origin. Salmonellosis is one of the most frequently reported foodborne diseases. Symptoms of salmonellosis are most severe in susceptible populations (the elderly, infants, and the infirm). Salmonella species are destroyed by normal pasteurization processes and are most commonly spread through contamination of processed materials with raw products or with the juices of raw products via hands, utensils, or food-contact surfaces. HACCP plans for processed foods should include controls to destroy and eliminate this organism and to prevent recontamination.
Staphylococcus aureus
Staphylococcus aureus may produce a very heat-stable enterotoxin when permitted to grow to an elevated level (>105 organisms/g). The foodborne intoxication is caused by ingestion enterotoxins produced in food by some strains of S. aureus, usually because the food has not been kept hot enough or cold enough. The organism is commonly isolated from hands and nasal passages of humans. Thus, foods which are handled or require preparation are at risk. The organism can grow at an aw of 0.86, and in high salt concentrations. Proper processing handling of raw materials is essential. If conditions allow the organism to grow and produce enterotoxins, subsequent thermal processing will destroy the vegetative organisms while the head-stable toxin persists. There is evidence that the enterotoxins may not be completely inactivated at retort temperatures (1210C or 2500F). HACCP plans should provide for proper handling of raw materials, steps to destroy, eliminate, or reduce the hazard and controls to prevent recontamination. If organisms can reasonably be expected in the final product, conditions to inhibit growth and toxin production should be controlled.
Clostridium perfringens
Clostridium perfringens is another anaerobic, spore-forming, rod-shaped bacterium. Perfringens food poisoning is caused by consuming foods that contain large numbers of those Clostridium perfringens that are capable of producing the food poisoning toxin, which is usually formed in the digestive tract and is associated with sporulation. Limited evidence exists that preformed toxin can be found in food. Perfringens food poisoning is frequently associated with food service operations; temperature abuse of prepared foods, such as large poultry or cooked cuts of meat and gravies and sauces prepared in large containers, can provide anaerobic conditions. Because spores are heat resistant, small numbers of organisms may be present after cooking (or large numbers after improper cooking). Subsequent temperature abuse (not keeping cooked foods above 600C; 1400F or not providing rapid, even cooling to refrigeration temperatures) may permit the organisms to multiply to food poisoning levels. HACCP plans should control proper cooking conditions and subsequent handling temperatures to inhibit growth of this organism.
Viral hazards
Viruses are very small particles that cannot be seen with a light microscope. They are obligate intracellular parasites that are unable to reproduce outside the host cell. Thus, they are inert in foods and do not multiply in them. However, viruses may be transmitted to foods via the fecal-oral route, either directly or indirectly. Some viruses may be inactivated in foods by thorough cooking and some by drying. However, contamination of foods with viruses should be avoided. Direct contamination can occur when an infected food handler contaminates food. Indirect contamination can occur when foods such as bivalve mollusks become contaminated in waters infected by untreated sewage. The viruses most commonly recognized as foodborne disease agents are summarized below.
Hepatitis A virus
Hepatitis A virus (HAV) is classified with the enterovirus group of Picornaviridae family. The terms hepatitis A or type A viral hepatitis have replaced all previous names for the illness. Hepatitis A is usually mild illness characterized by onset of fever, malaise, nausea, anorexia, and abdominal discomfort, followed in several days by jaundice. Occasionally, the symptoms are severe and convalescence can take several months. The incubation period for hepatitis A varies from 10 to 50 days (mean 30 days). The period of virus shedding or communicability extends from early in tile incubation period to about a week after the development of jaundice. The greatest danger of spreading the disease to others occurs 10-14 days before the first presentation of symptoms. The infectious dose is unknown but presumably is 10-100 virus particles.
The Norwalk virus family
Norwalk virus is the prototype of a family of unclassified small round structured viruses (SRSVs), which may be related to the caliciviruses. Common names of the illness caused by the Norwalk and Norwalk-like viruses are viral gastroenteritis and acute nonbacterial gastroenteritis. The disease is self-limiting, mild, and characterized by nausea, vomiting, diarrhea, and abdominal pain. Headache and low-grade fever may occur. The infectious dose is unknown but presumed to be low. Norwalk gastroenteritis is transmitted by the fecal-oral route via contaminated water and foods. Secondary person-to-person transmission has also been documented. Water is the most common source of outbreaks and may include water from municipal supplies, well, recreational lakes, swimming pools, and water stored aboard cruise ships. Salad ingredients and shellfish are the foods most often implicated in Norwalk outbreaks. Ingestion of raw or insufficiently steamed clams and oysters poses a high risk for infection with Norwalk virus. A variety of foods other than shellfish are contaminated by ill food handlers and include salads, fruits, eggs, clams, and bakery items.
Rotavirus
Rotaviruses are classified with the Reofiridae family. Rotaviruses cause acute gastroenteritis. Infantile diarrhea, winter diarrhea, acute nonbacterial infectious gastroenteritis, and acute viral gastroenteritis are names applied to the infection caused by the most common and widespread group A rotavirus. Rotavirus gastroenteritis is a self-limiting, mild-to-severe disease characterized by vomiting, watery diarrhea, and low-grade fever. The infective dose is presumed to be 10-100 infectious viral particles. Rotaviruses are transmitted by the fecal-oral route. Infected food handlers may contaminate foods that require handling and no further cooking, such as salads, and fruits.
Other viruses associated with gastroenteritis
Although the rotaviruses and the Norwalk family of viruses are the leading causes of viral gastroenteritis, a number of other viruses have been implicated in outbreaks, including astroviruses, caliciviruses, enteric adenoviruses, and parvoviruses. Astroviruses, caliciviruses, and the Norwalk family of viruses possess well-defined surface structures and are sometimes identified as “small round structured viruses” or SRSVs. Viruses with a smooth edge and no discernible surface structure are designated “featureless viruses” or “small round viruses” (SRVs). These agents resemble enterovirus or parvovirus, and may be related to them.
Parasitic protozoa and worm hazards
Parasites are organisms that derive their sustenance on or within their host. A variety of parasitic animals are of concern to the food microbiologist. They include protozoa, nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes). Some foodborne parasites may be transmitted through food and water contaminated by fecal material that contains parasites shed by infected hosts. Other parasites spend a portion of their life cycle in food animals and are thus ingested along with the food. Method for preventing transmission of parasites to foods via the fecal contamination route include good personal hygiene practices by food handlers, proper disposal of human feces, eliminating the use of insufficiency treated sewage to fertilize crops, and proper sewage treatment. Thorough cooking of foods will eliminate all foodborne parasites. Freezing, and in specific instances brining, may be used to destroy various parasites in foods.
Giardia Lamblia
Giardia Lamblia (intestinalis) is a single-celled protozoa that causes giardiasis in human. G.lamblia exists in two separate stages: the active feeding (trophozoite) stage and the infective environmental (cyst) stage in which the organism survives outside the host. Human giardiasis may involve diarrhea within a week after the cyst is ingested. Other symptoms include abdominal cramps, fatigue, nausea, flatulence, and weigh loss. The illness may loss for one to two weeks, but chronic infections may last months to years. Colonization and pathogenesis generally occur in the lumen of the small intestine, but the disease mechanism is unknown. Giardiasis is most frequently associated with the consumption of contaminated water. Outbreaks have been traced to food contamination by infected food handlers, and the possibility of infection from contaminated vegetables that are eaten raw cannot be excluded. Cool contamination by infected food workers can be prevented by proper personal hygiene. Thorough cooking of foods destroys G. lamblia.
Entamoeba histolytica
Entamoeba histolytica is a single-celled protozoa that predominantly infects humans and other primates. Like G. lamblia, E. histolytica can exist as two separate stage: a trophozoite or a cyst. Cysts survive outside in water, in soils, and on foods, especially under moist conditions. When swallowed, they cause infections by excysting (to the trophozoite stage) in the digestive tract. Infections can be accompanied by a mild gastrointestinal distress or dysentery (with blood and mucus). E. histolytica may penetrate the intestinal wall, and if it enters the blood, may gain access to other organs. Large numbers of cysts can be shed in the feces of infected individuals. Infection can result from the fecal contamination of drinking water and foods, and by direct contact with dirty hands or objects. Preventive measures are similar to those describes for G. lamblia.
Ascaris lumbriciodes
Humans worldwide are infected with Ascaris lumbriciodes. The eggs of this roundworm (nematode) are “sticky” and may be carried to the mouths by hands, other body parts, omits (inanimate objects), or foods. Asacariasis, the scientific name for this infection, is also commonly known as the “large roundworm” infection. Ingested eggs hatch in the intestine, and larvae begin to migrate, reaching the lungs through the blood and lymph systems. In the lungs, the larvae break out of the pulmonary capillaries into the air sacs, ascend into the throat, and descend again to the small intestine where they grow to sexual maturity. On occasion, larvae will crawl up into the throat and try to exit through the mouth or nose. Vague digestive tract discomfort sometimes accompanies the intestinal infection, but intestinal blockage may occur in small children who have more than a few worms because of the large size of the worms. Large numbers of eggs maybe voided in feces.
Chemical Hazards
Webster defines a chemical as any substance used in or obtained by a chemical process or processes. All food products are made up of chemicals, and all chemicals can be toxic at some dosage level. However, a number of chemicals are not allowed in food and others have established allowable limits.
Naturally occurring chemicals
The naturally occurring toxicants include a variety of chemicals of plant, animal, or microbiological origin. Although many naturally occurring toxicants are biological in origin, they have traditionally been categorized as chemical hazards. However, for individual HACCP programs, their inclusion in the biological hazard category would be equally appropriate. The following overview discusses several naturally occurring toxicants.
Mycotoxins
A number of fungi produce compounds (mycotoxins) toxic to man. Mycotoxins are secondary metabolites of certain fungi. Among some of the better known and studied groups of mycotoxins are the aflatoxins, which include a group of structurally related toxic compounds, produced by certain strains of the fungi Aspergillus flavus and A. parasiticus. Under favorable conditions of temperature and humanity, these fungi grow and produce aflatoxins on certain foods, grains, nuts, and feeds. The most pronounced contamination has been encountered in tree nuts, peanuts, and other oilseeds including corn and cottonseed.
Scombrotoxin (Histamine)
Scombroid poisoning or histamine poisoning occurs when foods that contain high levels of histamine (or possibly other vasoactive amines and compounds) are ingested. Histamine is produced by the microbial of histidine, a free amino acid found in abundance in dark-fleshed fish, including members of the Scombridae family from temperate and tropical regions. Fish that have been temperature abused are the most commonly implicated foods such as Swiss cheese have been reported to cause illness most often implicated are tuna, mackerel, bluefish, and amberjack.
Ciguatera
Ciguatera is a form of human poisoning caused by the consumption of tropical marine finfish, which have accumulated naturally occurring toxins through their diet. The toxins originate from several dinoflagellate (algae) species common to ciguatera endemic regions and accumulate through the food chain. Manifestations of ciguatera in humans usually involve gastrointestinal, neurological, and cardiovascular disorders.
Marine finfish most commonly implicated in ciguatera fish poisoning are predators and include the groupers, barracudas, snappers, jacks, mackerel, and triggerfish. Other species of warm-water fishes have been reported to harbor ciguatera toxins. The presence of toxic fish is sporadic; not all fish from a given locality or species will be toxic.
Mushroom toxins
Mushroom poisoning is caused by the consumption of raw or cooked fruiting bodies of certain higher fungi. Unlike the previously mentioned aflatoxins, which are secondary metabolites produced when a contaminating mold grows on a food product, the mushroom itself is the toxic food product. Many species of mushrooms are toxic and there is no general rule to distinguish between edible and toxic species. Mushroom poisonings are usually caused by ingestion of toxic wild mushrooms that have been confused with edible species.
Shellfish toxins
Shellfish poisoning is caused by a group of toxins elaborated by planktonic algae (dinoflagellates, in most cases) upon which the shellfish feed. Under the appropriate condition toxic dinoflagellate populations may increase to high levels and persist for several weeks. The shellfish may accumulate and metabolize these toxins during their filter feeding.
The food processor may control some of these naturally occurring chemical hazards by learning in which foods (i.e., sensitive ingredient) they are most likely to occur. Proper raw material specification, vendor certification, and guarantees along with inspection and spot checks will help to prevent introduction of natural chemical hazards into plant facilities. Likewise, proper handling and storage of sensitive ingredients will prevent conditions conducive to the production of other natural toxicants (e.g., proper storage of grains and feeds to prevent aflatoxin production and avoidance of temperature abuse of fish susceptible to scombroid poisoning).
Added Chemicals
The second groups of chemicals, which may be potential hazards, are those that are added to foods at some point between growing, harvesting, processing, storage, and distribution. These chemicals are generally not considered hazardous if proper conditions of use are followed. Only when these chemicals are misapplied or when their permitted levels are exceeded is there a potential hazard.
Toxic elements (e.g., lead, mercury, arsenic) and other toxic compounds (e.g., some chemicals used in the food processing plant) are either not allowed in food at all or have established maximum tolerances. In some cases, these chemicals are present naturally and have not been added to the food. Other added chemicals in the food additive group, including direct, secondary direct, and indirect food and color additives, are permitted to be used in actual food processing to preserve the food (e.g., preservatives), enhance flavor, impart color, or nutritionally fortify (e.g., vitamins and minerals). Secondary direct and indirect chemicals used in food processing plants include chemicals such as lubricants, cleaners, sanitizers, paint, and coatings, which may become incorporated into food via migration from packaging materials, or microorganisms and enzyme preparations used in food processing. Allowable limits for all of these food additives have been set in accordance with Good Manufacturing Practices (GMPs). At established limits, these chemicals are not hazardous and a large safety factor is incorporated into the regulatory limits; however, if tolerances are exceeded, potential health risks to consumers may occur.
Physical Hazards
Physical hazards are often described as extraneous matter or foreign objects and include any physical matter not normally found in food, which may cause illness (including psychological trauma) or injury to an individual.
The main physical hazards of concern include glass, wood, stones, metal, insects and other filth, insulation, bone, plastic, and personal effects. Other items include hair, dirt, paint and paint chips, rust, grease, dust, and paper. The sources of physical hazards include raw materials, water, facility grounds, equipment, building materials, and employee personal effects. Physical hazards may be added inadvertently during distribution and storage, or intentionally introduced (sabotage).
Methods involved in controlling physical hazards include raw material specifications and inspections along with vendor certification and guarantees. Various preventive measures are available to find and remove certain physical hazards. Metal detectors can be used to locate ferrous and nonferrous metals in foods; various foreign objects, especially bone fragments can be found through X-ray technology. Effective pest control and foreign object removal from plant environments are also essential. Preventive maintenance and sanitation programs for plants and equipments are necessary. Proper shipping, receiving, distribution and storage procedures as well as packaging material handling practices (particularly those involving glass) must be evaluated for their potential to introduce hazards. Packaging should be tamper-proof and at least tamper-evident. Finally, employee education and practices must involve knowledge and prevention of physical hazard introduction.
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