Food Contamination and Prevention

Food Contamination

Everybody at one time or another has had the experience of eating food and sometime later becoming sick. This is called food poisoning. The symptoms may include nausea, vomiting, stomach pains, diarrhea, feeling weak, fever or chills/sweating and headache etc. Food poisoning can be caused by eating food contaminated with bacteria, viruses, chemicals or poisonous metals such as lead or cadmium. Food which has become contaminated with harmful bacteria does not always taste bad. Where it looks smells and tastes like it normally does in most of the times. However, some food poisoning diseases are more common than others, i.e. disease caused by Staphylococcus aureus occurs a lot more often than disease caused by Clostridium botulinum. Thus food contamination is a major problem in the consumer market which may be considered as the occurrence of any obnoxious problem within or on the food. i.e. slaughtered carcasses may be contaminated with spoilage or food poisoning bacteria while grains can be contaminated with rodent droppings or hairs. Thus prevention of consumption of such food is necessary to control food poisoning where minimizing the contamination from such sources is mandatory. On the other and contaminated food will create havocs in market where manufacturer loose the consumers while he is liable for the causes generated.

Food Safety Hazards

There are four kinds of food safety hazards or contamination types, which are:

Microbiological Hazards

Microbiological hazards caused by microorganisms such as bacteria, mould, viruses and parasites. The root causes of biological contaminations in food production facilities are usually occurs due to ignorance, poor design, inadequate space, or due to the wrong practices used by food handlers. These types of problems are not visible in the initial stages, but such contaminations are very dangerous which may result in food spoilage, food poisoning and death.

Physical Hazards

Physical hazards are occurs due to the foreign objects including insects. Physical contaminations are usually unpleasant or nuisance which leads to food is unfit or unsafe for consumption. The usual objects are plastic, glass, stones, paper, hair string or metal.

Chemical Hazards

Chemical hazards are basically due to the addition of unwanted or overdosed chemical compounds which may be used for other proposes within the manufacturing facility. The chemical contaminations also lead to food spoilage, food poisoning or death. This includes pesticides, herbicides, cleaning chemicals as well as overdosed preservatives or other additives.   

Allergenic Hazards

The allegiances happen due to extra sensitivity of certain consumer groups such as young and elderly or pregnant due to the abnormal reactions by the immune system where immune system generates antibodies by misjudging the certain food products. The allergenic reaction can cause minor irritation to the immediate death. The major food allergenic foods are milk, peanuts, eggs and cereals.       

Microbiological Hazards

Bacterial contamination of food is the most significant among all the food poisoning incidents, because bacterial growth is very fast and their environmental requirements are diverse where they spoil large amounts of food products in various processing steps while generating lots of food poisoning outbreaks.  The source of contamination of microbiological hazards can be listed as;

Raw materials such as fruits, vegetables, cereals, poultry, meat, milk, eggs or fish etc.;

Insects, rodents, animals and birds;

Working environment including soil or dust;

Food handlers or visitors;

The mould spores are present in the environment which includes air, surfaces and mould contaminated foods. Thus all the food must be coved or keep airtight while segregating them from the mouldy foods. In addition, mould growth over tabletops, walls, ceilings and window frames or window sills must be prevented which happens due to the optimum temperature for growth, high humidity and availability of food source as well as excess of recommended shelf life. The other major reason is mechanical damages to the product packaging expose food to the environment which create contamination opportunities and mould growth inside the product.  

The viruses are usually contaminated through food handlers and visitors, or through raw materials such as shellfish which have been grown in sewage-polluted water.

Microbial Food Spoilage

Damage to food that is caused by microorganisms (bacteria, moulds and yeasts) and they can grow in almost all kinds of food products. As they occur everywhere around us, there is always a risk of microbial spoilage and most of them can grow in a variety of products under the right conditions. The growth is dependent of the kind of food, the type of microorganism, the temperature and other factors.  I.e. Dry products such as bread and cookies do not have enough moisture to allow bacterial growth where spoilage to these products is usually caused by moulds. Sour, salted or sugary products do not provide good growth environments for most microorganisms. They can be harmed by specific spoilage flora that have adapted to them.

 

Bacteria are round, rod or spiral shaped microorganisms. Bacteria may grow under a wide variety of conditions. There are many types of bacteria that cause spoilage which can be further divided into spore-forming and non-spore forming. Bacteria generally prefer low acid foods like vegetables and meat. In order to destroy bacteria spores in a relatively short period of time, low acid foods must be processed for the appropriate length of time at 116°C (240°F) in a pressure canner.  Yeasts growth causes fermentation which is the result of yeast metabolism. There are two types of yeasts true yeast and false yeast. True yeast metabolizes sugar producing alcohol and carbon dioxide gas. This is known as fermentation. False yeast grows as a dry film on a food surface, such as on pickle brine. False yeast occurs in foods that have a high sugar or high acid environment. Moulds grow in filaments forming a tough mass which is visible as `mould growth'. Moulds form spores which, when dry, float through the air to find suitable conditions where they can start the growth cycle again. Mould can cause illness, especially if the person is allergic to molds. Usually though, the main symptoms from eating mouldy food will be nausea or vomiting from the bad taste and smell of the mouldy food. Both yeasts and moulds can thrive in high acid foods like fruit, tomatoes, jams, jellies and pickles. Both are easily destroyed by heat. Processing high acid foods at a temperature of 100°C (212°F) in a boiling water canner for the appropriate length of time destroys yeasts and moulds.

Modes of Bacterial Contamination   

The contamination of bacterial cells are mostly depend on the carriers rather than direct contamination from the source to high risk foods, because bacteria are largely static and the source is not directly in contact with food product. Thus bacteria have to rely on other sources of transportation to the food product which are called as vehicles of contamination. The major vehicles are;

Hands

Hand-contact surfaces

Cloths and equipment

Food-contact surfaces

The contaminations routes are mostly indirect where cross contamination is the major route. The cross contamination is called as transfer of bacteria or spores from contaminated food to uncontaminated foods. The path which was used by bacteria to transfer from the contaminated food into uncontaminated food is called route. Thus creation of awareness on sources, vehicles and routes are very important in prevention of microbiological contamination. I.e. if the food handler understand that, use of unwashed hands between raw and cooked foods preparation, or use of the same equipment without cleaning or non-sanitized table tops can transfer bacteria from raw foods to cooked foods, he will sanitize his hands as well as with other necessary precautions to eliminate the problem.

If you are really considering of preventing microbiological contaminations, you must assume that, all the equipment, machinery, work surfaces and the environment are contaminated with bacteria where you will control all of them before start the production.  The prevention of contamination based on the removal or eliminating of the sources or building barriers between bacteria and the vehicles or source and the foods where human access to food must be restricted, while raw foods handle in separate areas with appropriate pest control mechanisms. Furthermore, work areas must be enclosed into properly designed, suitably constructed and ventilated buildings and movements of vehicles must be minimized as much as possible and handling of products must be minimized. Minimize the use of wiping cloths or destroy them immediately after each use, hand contact surfaces. Use knee, elbow or electronically operated taps in the production areas instead of hand operated taps. Limit the number of surfaces to be contacted while preparation of foods. However, routes between sources and vehicles survive giving rise to the contaminated vehicles where routes must be disrupted by cleaning and disinfection on a routine basis.

Preventive Controls for Contamination

Use of registered and certified suppliers who are well known and reliable for raw materials, ingredients and other food items.

Verify before accepting all the deliveries for the GMP which needs to be transported in properly cleaned and equipped vehicles with clean drivers wearing satisfactory protective clothing. Refrigerated vehicles and application of cold chain practices may be a necessity.

Verified goods must be transferred immediately to an appropriate cold or dry storage according to the raw material storage requirements.

Remove and return rejected materials to the suppliers, segregate chemicals, spoiled food items, refuse and store or discard them accordingly. Use food containers only for storing predefined materials.

Segregate high risk food items from raw materials and store separately, with separate utensils and equipments as well as with separate food handlers whenever necessary. Application of different colour codes will be helpful.  

Strictly maintain scrupulous personal hygiene at all levels and at all the times while handling food as little as possible and exclude potential carriers.

Keep food items covered or otherwise protected if it is not under preparation or processing, and don’t take out of stores if food items are not being utilized for processing. Don’t leave foodstuffs are lying around.

Maintain food hygiene on the premises, cleaning of utensils and equipment as well as repairs to be complete without delays. Disinfect the food contact surfaces, hand contact surfaces and cleaning equipment.

Ensure that all empty containers are clean and disinfected prior to re-filling with foodstuffs.

Control cleaning materials, particularly wiping cloths. Keep cleaning materials away from the foodstuffs. Remove foodstuff and food containers before cleaning where care must be taken ensure that all cleaning residues, including water are drained from equipment and pipes. The cleaning must be start from high risk areas to low risk areas.

Remove waste foodstuff and refuse from the food processing and storage areas as soon as possible which must be stored in appropriate containers away from food items.

Maintain an active pest control programme.

Control of visitors and food handlers in high risk areas are vital to control of food safety where application of hygiene disciplines to all operators including management is mandatory.

Inspection of food manufacturing areas, and processes in a predefined frequency is necessary where care must be taken to act fast on defects or unhygienic practices detected. Train the staff and use performance evaluations to see the impact where food handlers and engineers must be aware of the bacteriological and physical contamination and their impact on human health.

Ensure adequate thawing of foods, and separate from other foodstuff.

Make suitable provisions for cooling food items prior to refrigeration.       

How to Write a Risk Profile for Your Food Safety System

What is a Risk Profile?

When you prepare a HACCP plan, it is mandatory to consider risk profiles of the possible microbes, fungus, virus toxins, physical objects, chemical contaminants etc. However, it is not that easy to prepare a risk profile, because you need to study the possible risk factors and need to collect all the available and reliable published data about the list you have summarized from your hazard identification. The risk profile is called a written description of a set of risks where a risk profile can include the risks that the entire organization must manage or only those that a particular function or part of the organization must address. Risk is often measured in terms of risk probability or the likelihood that a risk will occur and risk impact which is a measure of the consequences. Risk analysis is a process that is used to understand the nature, sources, and causes of the risks that you have identified and to estimate the level of risk. It is also used to study impacts and consequences and to examine the controls that currently exist. How detailed your risk analysis ought to be will depend upon the risk, the purpose of the analysis, the information you have, and the resources available.

Hazard identification is the first step of the work and then you need to start collecting data where you can run your hazard analysis based on these initial facts. But when you realize your real hazard which you are going to control through your critical control points; you need to document their basic facts as a summery sheet while considering the most important and critical facts which are necessary to control them as well as to educate your food safety team and the entire work force. It is also good point, if you can disseminate those basic data to your consumers, because certain products are semi processed or raw at the time of selling and your consumer has to carry out the final preparations before eating. Thus it is better to educate them on the critical control points of the processing methods (i.e. if it is cooking, you can provide the final temperature that product must reach) and why this is important. If you also provide the right information, consumer may be able to understand the severity of a certain toxin or a microbe and they will start looking for the properly prepared foods, which may be an opportunity for the manufacturer to show his dedication to the clients.

On the other hand, you don’t need to document all the data collected for the hazard analysis or whatever available, instead you can write down a small summary about a particular contaminant and its basic information everybody needs to understand. This will give you a pretty good idea of the risk involved and the criticality.

The following example can be considered as a little guide to what you need to consider, but it is not a comprehensive risk profile. The risk profile was written considering the orthodox black tea manufacturing process where focus is tea related risk identification.

Risk Profile – E. coli

Introduction

Escherichia coli are in the family Enterobacteriaceae, gram negative, rod shaped, non-spore forming, and motile or non-motile. They can grow under aerobic and anaerobic conditions where grow best at 37⁰C. Therefore it is easy to eradicate by simple boiling or basic sterilization. 

E. coli O157:H7 is a well-studied strain of the bacterium E. coli, which produces Shiga-like toxins, causing severe illness. E. coli is transmitted to humans primarily through consumption of contaminated foods, faecal contamination of water and other foods. Infectious dose of E. Coli is 10⁶ - 10⁸ logs of organisms.

The tea leaves are plucked and heaped on the floor or in the field and transported to the factory with high risk of contamination or cross contamination from humans due to handling. The raw material further directly handled by many operators during withering, rolling, fermentation, sifting and packing, which increase the risk of E. coli infection. Hence, there is a risk for E. coli contamination in the product due to poor personal hygiene and improper cleaning of utensils. Luckily the organism’s heat sensitivity makes it possible to eliminate with LTHT treatment. The severity of the disease in combination with the risk makes E. coli a hazard to target in the HACCP plan.

Disease, Symptoms and Onset  

Symptoms include abdominal cramps and diarrhea, fever and vomiting may also occur. The incubation period can range from three to eight days, with a median of three to four days. Most patients recover within 10 days, but infection may lead to a life-threatening disease, such as hemolytic uremic syndrome (HUS).

Main Disease Factor

Commonly found in the lower intestine of warm-blooded organisms (endotherms).

Source

E. coli is almost exclusively of faecal origin and it is transmitted through faecal contamination of foods and water, as well as cross-contamination, or by direct human contact during food preparation.  

Transmission

E. coli is transmitted to humans primarily through consumption of contaminated foods such as faecal contamination of water, as well as cross-contamination during food preparation (contaminated surfaces and utensils). Waterborne transmission has been reported, both from contaminated drinking-water and from recreational waters. Person-to-person contact is an important mode of transmission through the oral-faecal route.

Characteristics

E Coli can grow in temperatures ranging from 7°C to 50°C. Some EHEC can grow in acidic foods, down to a pH of 4.4, and in foods with a minimum water activity (Aw) of 0.95. It is destroyed by thorough cooking of foods until all parts reach a temperature of 70°C or higher.     

Histamine Fish Poisoning

What is Histamine?

Histamine fish poisoning is among the most common toxicities related to fish ingestion, constituting almost 40% of all seafood-related foodborne illnesses reported to the US Centers for Disease Control and Prevention (CDC) where histamine fish poisoning results from the consumption of inadequately preserved and improperly refrigerated fish. It resembles an allergic reaction but is actually caused by bacterially-generated toxins in the fish's tissues. Previous terms for histamine fish poisoning were scombroid fish poisoning, pseudo-allergic fish poisoning, histamine overdose, or mahi-mahi flush. The term scombroid was used because the first fish species implicated in this poisoning were from the suborder Scombridae, which includes mackerel, tuna, marlin, swordfish, albacore, bonito, skipjack, and almost 100 other species whereas term histamine fish poisoning is now considered more appropriate because many cases are from non-scombroid fish. Examples include mahi-mahi, amberjack, herring, sardine, anchovy, and bluefish.

Scombrotoxin (histamine) formation as a result of time and temperature abuse of certain species of fish can cause consumer illness whereas the illness is closely linked to the development of histamine in these fish. In most cases, histamine levels in illness-causing fish have been above 200 ppm, often above 500 ppm. However, there is some evidence that other chemicals (e.g., biogenic amines such as putrescine and cadaverine) may also play a role in the illness.

Histamine is an organic amine that is produced as part of a local immune response to cause inflammation which also performs several important functions in the bowel and acts as a neurotransmitter or chemical messenger that carries signals from one nerve to another. Histamine is secreted by basophils and mast cells as part of a local immune response to the presence of invading bodies. The basophils and mast cells are found in nearby connective tissue. This histamine release causes capillaries to become more permeable to white blood cells and other proteins, which proceed to target and attack foreign bodies in the affected tissue. Aside from humans, histamine is found in virtually all animals.

Histamine, 4-(2-aminoethyl)imidazole (MW = 111), is a primary amine arising from the decarboxylation of the amino acid L-histidine. This chemical reaction is catalyzed by the enzyme L-histidine decarboxylase. Histamine is a hydrophilic vasoactive amine and once formed, it is either quickly inactivated or stored. When released at synapses, it is broken down by acetaldehyde dehydrogenase. When this enzyme is deficient, there is an increased risk of allergic reactions, as histamine accumulates in the synapses. Histamine is broken down by the enzymes diamine oxidase and histamine-N-methyltransferase. Thus, histamine formed in foods is the result of the growth of bacteria that possess the enzyme histidine decarboxylase.

Scombrotoxin poisonings have primarily been associated with the consumption of tuna, mahi mahi, and bluefish where scombrotoxin formation that causes consumer illness is closely linked to the development of histamine in these fish. However, a number of other species are also capable of developing elevated levels of histamine as a result of time/temperature abuse. Histamine is heat-stable and survives thermal processing.

Bacterial Scombrotoxin (Histamine) Formation

Certain bacteria produce the enzyme histidine decarboxylase during growth. This enzyme reacts with histidine, a naturally occurring amino acid that is present in larger quantities in some fish than in others. The result is the formation of scombrotoxin (histamine). Histamine-forming bacteria are capable of growing and producing histamine over a wide range of temperature. Development of histamine concentration is more rapid, however it is particularly rapid at temperatures near 90°F (32.2°C), but histamine growth is somewhat retarded at moderate-abuse temperatures (e.g., 45°F (7.2°C) than at high-abuse temperatures (e.g., 70°F (21.1°C) or higher). Thus histamine is more commonly the result of high temperature spoilage than of long-term, relatively low temperature spoilage, which is commonly associated with organoleptically detectable decomposition. Nonetheless, there are a number of opportunities for histamine to form under more moderate-abuse temperature conditions.

Once the enzyme histidine decarboxylase is present in the fish, it can continue to produce histamine in the fish even if the bacteria are not active because the enzyme can be active at or near refrigeration temperatures. On the other hand, enzyme remains stable while in the frozen state and may be reactivated very rapidly after thawing whereas freezing may inactivate some of the enzyme forming bacteria. Both the enzyme and the bacteria can be inactivated by cooking. However, once histamine is produced, it cannot be eliminated by heat (including retorting) or freezing. After cooking, recontamination of the fish with the enzyme-producing bacteria is necessary for additional histamine to form. For these reasons, histamine development is more likely in raw, unfrozen fish but should not be discounted in other product forms of scombrotoxin-forming fish species. The kinds of bacteria that are associated with histamine development are commonly present in the saltwater environment. They naturally exist on the gills, on external surfaces, and in the gut of live, saltwater fish, with no harm to the fish. Upon death, the defense mechanisms of the fish are no longer inhibiting bacterial growth in the muscle tissue, and histamine forming bacteria may start to grow, resulting in the production of histamine.

Critical Processing Operations

Evisceration and removal of the gills may reduce, but not eliminate, the number of histamine forming bacteria. Packing of the visceral cavity with ice may aid in chilling large fish in which internal muscle temperatures are not easily reduced. However, when done improperly, these steps may accelerate the process of histamine development in the edible portions of the fish by spreading the bacteria from the visceral cavity to the flesh of the fish. With some harvesting practices, such as long lining and gillnetting, death may occur many hours before the fish is removed from the water. Under the worst conditions, histamine formation can already be underway before the fish is brought onboard the vessel. This condition can be further aggravated with certain tuna species that generate heat, resulting in internal temperatures that may exceed environmental temperatures and increasing the likelihood of conditions favorable to growth of enzyme forming bacteria. The potential for histamine formation is increased when the scombrotoxin-forming fish muscle is in direct contact with the enzyme forming bacteria. This direct contact occurs when the fish are processed (e.g., butchering or filleting) and can be particularly problematic when the surface-to-volume ratio of the exposed fish muscle is large, such as minced tuna for salads.

Even when such products are prepared from canned or pouch retorted fish, recontamination can occur during salad preparation, especially with the addition of raw ingredients. The mixing spread the bacteria throughout the product and the high surface-to-volume ratio can result in substantial histamine formation if time and temperature abuse occurs. At least some of the histamine forming bacteria are halotolerant (salt tolerant) or halophilic (salt loving). Some are more capable of producing histamine at elevated acidity (low pH). As a result, histamine formation is possible during processes such as brining, salting, smoking, drying, fermenting, and pickling until the product is fully shelf-stable. Refrigeration can be used to inhibit histamine formation during these processes. A number of the histamine forming bacteria are facultative anaerobes that can grow in reduced oxygen environments. As a result, reduced oxygen packaging (e.g., vacuum packaging, modified atmosphere packaging, and controlled atmosphere packaging) should not be viewed as inhibitory to histamine formation. Histamine is water soluble (dissolves in water) and would not be expected in significant quantity in products such as fish oil that do not have a water component. However, histamine could be present in products such as fish protein concentrate that are prepared from the muscle or aqueous (water-based) components of fish tissue.

Symptoms

When a person is allergic to a particular substance, such as a food or dust, the immune system mistakenly believes that this usually harmless substance is actually harmful to the body. In an attempt to protect the body, the immune system starts a chain reaction that prompts some of the body's cells to release histamine and other chemicals into the bloodstream. The histamine then acts on a person's eyes, nose, throat, lungs, skin, or gastrointestinal tract, causing allergy symptoms. You've probably heard of antihistamine medications - these help to fight symptoms caused by the release of histamine during an allergic reaction. Thus increase in blood histamine levels due to consumption of contaminated fish or fish products create similar situations.  The symptoms of scombrotoxin poisoning include tingling or burning in or around the mouth or throat; rash or hives on the upper body; drop in blood pressure; headache; dizziness; itching of the skin; nausea; vomiting; diarrhea; asthmatic-like constriction of the air passage; heart palpitation; and respiratory distress. Symptoms usually occur within a few minutes to a few hours of consumption and last from 12 hours to a few days.

Controlling Scombrotoxin (Histamine) Formation

Rapid chilling of scombrotoxin forming fish immediately after death is the most important element in any strategy for preventing the formation of scombrotoxin (histamine), especially for fish that are exposed to warm waters or air, and for tunas which generate heat in their tissues. Following methods can be used to reduce or control the histamine formation:

Fish exposed to air or water temperatures above 83°F (28.3°C) should be placed in ice, or in refrigerated seawater, ice slurry, or brine of 40°F (4.4°C) or less, as soon as possible after harvest, but not more than 6 hours from the time of death; or

Fish exposed to air and water temperatures of 83°F (28.3°C) or less should be placed in ice, or in refrigerated seawater, ice slurry, or brine of 40°F (4.4°C) or less, as soon as possible after harvest, but not more than 9 hours from the time of death; or

Fish that are gilled and gutted before chilling should be placed in ice, or in refrigerated seawater, ice slurry, or brine of 40°F (4.4°C) or less, as soon as possible after harvest, but not more than 12 hours from the time of death; or

Fish that are harvested under conditions that expose dead fish to harvest waters of 65°F (18.3°C) or less for 24 hours or less should be placed in ice, or in refrigerated seawater, ice slurry, or brine of 40°F (4.4°C) or less, as soon as possible after harvest, but not more than the time limits listed above, with the time period starting when the fish leave the 65°F (18.3°C) or less environment.

Detection

Sensory Evaluation – Sensory evaluation is generally used to screen fish for indicators of spoilage that develop when the fish is exposed to time and temperature abuse. Odor in particular is an effective means of detecting fish that have been subjected to a variety of abusive conditions. However, odors of decomposition that are typical of relatively low temperature spoilage may not be present if the fish has undergone high temperature spoilage. This condition makes sensory examination alone an ineffective control for preventing scombrotoxin (histamine) formation.

Enzyme Immunoassay – The enzyme immunoassay for histamine is based on the competition between the histamine to be assayed and the histamine-alkaline phosphatase conjugate, for binding to antibody directed against histamine, coated onto microtiter wells. The sample containing the histamine, and the histamine-alkaline phosphatase conjugate, when added to the microtiter wells, compete for binding to a limiting number of antibody sites. After incubation, each well is rinsed in order to remove non-bound components. The bound enzymatic activity is then measured by the addition of a chromogenic substrate. The intensity of the color developed is inversely proportional to the concentration of histamine in the sample. The concentration is estimated by comparison with standard histamine solution.