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How to protect food from contamination during distribution and marketing

How to protect food from contamination during distribution and marketing
 By Dr. Daniel Karugu.

Food safety measures are a continuum from farm to fork. Food contamination may occur at any level in the continuum while food decontamination can be done at certain critical points in the process. This message is targeting handlers and traders at the level of distribution and marketing of food. It intends to achieve reduction of contamination of food during distribution and marketing. Distribution comprises collection, bulking and transportation of food to the market, while marketing includes wholesaling and retailing of food as well as hotels, restaurants and other eateries.

Contamination points for food during distribution and marketing include the process of bulking, packing and loading, the containers, carriages, vessels and equipment used in transportation, the conditions observed during transport, the premises and their hygiene status in storage and processing, wholesaling and retailing facilities and the containers and wrappings used in delivering the food to end-buyers.

The contaminants in food distribution and marketing include physical agents such as soil and stones that may inadvertently picked from the collection and bulking environment and the biological agents from the bodies, hands and clothes of the handlers or picked from contaminated premises and environment such as Campylobacter jejuni, Clostridium perfringens, Entamoeba histolytica, Shiga toxin-producing Escherichia coli, Enterotoxigenic E. coli, Giardia intestinalis, Hepatitis A virus, Non-typhoidal Salmonella, Rotaviruses, Salmonella Typhi, Shigella species, Staphylococcus aureus, Streptococcus pyogenes, Taenia solium and Vibrio cholera. Contaminants may also include chemical agents such as detergents and pesticides used in food stores, heavy metals in the environment, and misused preservatives.

Food safety controls

Food safety controls are applied in distribution and markets to limit the entry of these pathogenic agents in food and also to prevent their multiplication or perpetuation through the food.

Food destined for the market should be wholesome. According to Kenya’s Food, Drugs and Chemical Substances Act, Cap 254, and the international “food law” known as the Codex Alimentarius, the responsibility for meeting the wholesomeness requirements of food at collection rests with the primary producers. A safety certification system should be applied at primary producer level as a prerequisite to supplying food to the market. For meat, a live animal health inspection is embedded in the movement permit as set out in the Animal Diseases Act, Cap. 364; an ante-mortem (i.e. before slaughter) inspection is also available as provided in Public Health Act, Cap 242, and the Meat Control Act, Cap. 356. For milk, such a system is provided by the Milk and Dairy Rules of the Public Health Act. Eggs supplied to the market are required to be free of Salmonella species. Similarly crop-derived food should be supplied to the market in wholesome state and it behooves primary producers to assure as such. Where an inspection and certification system is not in place, primary producers should insist on its institutionalization since they carry the responsibility of the wholesomeness of whatever food they supply. Similarly, primary buyers should source the food from reputable primary producers and should also insist on a safety inspection and certification since the burden of assuring wholesomeness of the food shifts to them after the transaction.

Collectors, bulkers, packers and loaders of food should ensure that the food is free of soil, stones and other physical contaminants. Primary cleaning for such foods as fruits and vegetables should be done at the bulking facilities and this should be done using portable water, meaning water that is palatable and free of pathogenic agents. Separation of waste, soil and stones in cereals and pulses should also be done, either at the primary producers’ or at the bulking facilities.

Collectors, bulkers, packers and loaders of food should be healthy and any person suffering from a communicable disease transmissible through food should desist from handling food, including persons with symptoms such as diarrhea, vomiting, open skin sores, boils, fever, dark urine, or jaundice. These personnel should also be clean and should wear clean protective clothing at all times when handling food.

A food collection, bulking, packing and loading facility that uses portable water for its operations, provides sanitary conveniences and whose staff wears clean protective clothing would provide added confidence on the wholesomeness of the food emanating from it.

Controls in food transportation

The safety issues in food transportation are the human handling concerns, the suitability and hygiene of the vessel and containers and the temperature management en route. As in the collection and bulking process, food handlers in transportation should be healthy, should be clean and should wear clean protective clothing.

The container in which food is transported should be made up of food-grade material, meaning safe, non-corrosive, smooth-surfaced and inert material that does not contaminate food with harmful substances or alter the characteristics of food when in contact with it. Examples of food-grade material is High Density Polyethylene plastic when used for short time hot pack temperatures, 200, 300 or 400 Series stainless steel, Aluminum Alloy Series 1000, 3000, 4000, 5000 and 6000, and glass, though the use of the latter is limited due to breaking.

The following must never be used as food contact surface: lead solder, non-food grade plastic, galvanized steel, mild carbon steel, brass, bronze, copper or wood.

Containers, packaging and transporting vessels such as trucks and vans should be cleaned, sanitized and dried before loading with food. The process of cleaning and sanitizing involves sweeping away solid matter, scabbing with water and detergent, rinsing with portable water and sanitizing with water heated above 75°C or with food-safe chemicals such as chlorine dioxide. Drying can be in air or on a drying rack.

The management of temperature is very important for protecting the safety of food during transportation. Low temperature limits the multiplication of any pathogenic and spoilage contaminants of food. Food should therefore be transported under controlled temperature, except for short distances; meat, poultry, fish and fruits and fruit-juice concentrates are best deep-frozen at below -18°C while fresh meat, poultry, fish and meat and dairy products are best chilled between 2°C and -2°C. Melons should be transported at moderate temperatures of 6-9°C while some foods such as bananas, cucumbers and grapefruits are safely transported at moderate temperatures of 12-16°C. It is important therefore for food transporters to consider the food they are transporting, understand their temperature requirements, and prevent abuse of such temperatures.

Controls in food storage and processing facilities

Food is invariably stored during the distribution and marketing process. It is at the storage facility that a lot of physical damage and gross multiplication of spoilage and pathogenic microorganisms may occur. The storage facility should therefore be clean and sanitized in the same manner as done in transportation vessels and containers; the same temperature management should also be upheld.


Moisture management of the food and of the storage environment is essential. The problems of mycotoxins, such as aflatoxicosis, are a consequence of abuse of moisture requirements. According to Codex Alimentarius, the maximum moisture content should be 15.5% for maize, 14% for oats, 15% for rice, 14.5% for sorghum grain, 15% for sorghum flour, 14.5% for wheat grain, 15.5% for wheat flour and 13% for millet grain; these foods should be stores in a facility that does not increase moisture above these contents. These standards apply even when these foods are used for the manufacture of animal feedstuffs.


The safety of the raw food materials, the hygiene of the personnel and processing facility, the safety of the equipment used and the packaging of the final product all influence the safety of processed food.

Whereas some microbial contaminants may be eliminated from food during such processing steps as heat-treatment, physical and chemical contaminants cannot be eliminated at this level; only safe food should be therefore be processed.

Personnel serving in food handling departments of a processing plant should be healthy and should only work if free of symptoms such as diarrhea, vomiting, open skin sores, boils, fever, dark urine, or jaundice. Each personnel is required to procure a medical certificate issued by a government medical institution every 6 months. They must also be clean and wear clean personal protective clothing. Personnel must also be continuously trained on hygienic practices and on food protection.

The food processing plant should only operate if it is licensed and this is done after inspection to ascertain that it meeting sanitary conditions. The grounds surrounding a food plant must be kept free from contaminating conditions such as litter, waste, effluent, filth, and vermin, according to the Food, Drugs and Chemical Substances Act.  The design, layout and construction of a food processing plant shall be suitable for facilitating easy maintenance and sanitary food production. The suitability is with respect to space allocation, clear separation of unsafe and safe operations, lighting, sanitary conveniences, ventilation, use of food-grade materials and equipment, protection from animals, birds and vermin, use of portable running water at correct temperature and general good state of repair. Subsequent to acquiring the license, the food processing plant should be maintained at clean and hygienic levels at all times and a responsible person specifically assigned to supervise the sanitizing processes in the plant.

Food processing may involve use of food preservatives which prolongs the shelf-life of the commodity and lowers microbial multiplication. Food processors should be conversant with the legally approved preservatives and their level of use, the labeling requirements upon their use, and also the prohibited and restricted preservatives. The Food, Drugs and Chemical Substances Act and the Codex Alimentarius provides a list of approved, prohibited and restricted chemical food preservatives in Kenya. These include;

  • acetic acid and ascorbic acid in meat, poultry and fish under Good Manufacturing Practice;
  • citric acid in unstandardized foods under Good Manufacturing Practice, except unstandardized meats, poultry and fish;
  • sorbic acid in apples, fruit juices and fruit pastes in less than 1,000 parts per million (ppm);
  • potassium or sodium nitrate in meat and poultry in not more than 200 ppm
  • sulphurous acid, sodium meta-bisulphate and potassium meta-bisulphate in 3 not more than 500 ppm in honey, wine, beer, apples, fruit juices, soft drinks, dried fruits and vegetables and unstandardized foods except food that is source of thiamine and except unstandardized meat and meat products, poultry and poultry products and fish.

The standards for various meats and other foods are laid out in the Food, Drugs and Chemical Substances Act.

All preserved food shall be labeled as prescribed to declare the name of the preservative used. The use of prohibited preservatives or also the use of approved preservatives in concentrations higher than the standard or the sale of unlabelled but preserved food is an offence in law.

Controls in food marketing

The food safety concerns in food marketing are the hygiene of premises used, the safety of equipment, utensils and wrappings and the portability of water used. Wholesale and retail markets, supermarkets, hotel, restaurants and other eateries are food plants for the purpose of the Food, Drugs and Chemical Substances Act. Operators of these food outlets should therefore comply with the measures described above under food processing plants with respect to personnel hygiene and medical certification, hygiene of premises and water, and the food-grade requirements for equipment, utensils and wrappings of food and on licensing.

It is prohibited under the Public Health Act, Cap 242, for a person to reside or sleep in any kitchen or room in which foodstuffs are prepared or stored for sale; the Act also prohibits the sale or exposure for sale of any food for man in a tainted, adulterated, diseased or unwholesome state, or which is unfit for use, or any food for any animal which is in an unwholesome state or unfit for their use. It also empowers any medical officer of health, veterinary officer, sanitary inspector, meat inspector or police officer of or above the rank of Inspector to seize any such food, and any magistrate on the recommendation of the medical officer of health, a sanitary inspector or a veterinary officer to order it to be destroyed or disposed to prevent it from being used as food for man or animal as the case may be.

  • Dr Karugu works in the Veterinary Public Health Division of the Directorate of Veterinary Services in Nairobi City County Food, Agriculture and Forestry Sector. The views in this article are his professional opinions and do not necessarily reflect the opinions of the Nairobi City County Government.



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