CHEMICAL POLLUTANTS FORMED DURING THE COOKING OF FOOD

Food: Defined as any substance, processed, partially processed or unprocessed, that is eaten, drunk or expected to be eaten or drunk by people.

Safe Food:

Food material that is free from all agents of deterioration and disease, poses no health risk, is suitable for consumption and has not lost its nutritional value.

Food materials are processed to:

• Facilitate their storage and transport, • Make various nutrients available in seasons and regions where they are not naturally present, • Improve their taste and appearance, • Simplify their preparation and cooking, • Increase variety, • Eliminate harmful substances in their composition, • Enhance nutritional value through combinations, • Safely extend their shelf life.

Chemical Contaminants:

May contaminate food at any stage of the production-processing-storage-distribution-sales chain or may be formed during food processing; they can cause serious health problems through toxic, carcinogenic or mutagenic effects. Responsibility for food safety lies not only with each link in the production-processing-storage-distribution-sales chain but also with the consumer.

Contaminants Formed During Cooking:

Cooking aims to enhance flavour, facilitate nutrient digestion and eliminate microorganisms. However, high temperature application results in loss of nutrients and formation of various toxic, mutagenic and carcinogenic compounds.

1. Polycyclic Aromatic Hydrocarbons

Polycyclic Aromatic Hydrocarbons are formed as a result of the combustion of products such as smoke, tar, soot, coal and petroleum.

PAHs contaminate food in two ways:

• Accumulation of gases and smoke produced by combustion of coal and petroleum products in the atmosphere; contamination and deposition from air to soil, water and food. • Formation in food through thermal processes used during grilling, smoking and frying with barbecue/charcoal.

Factors affecting PAH formation in food:

Cooking method, fuel type, duration of food smoking and fat content of the food. PAHs are formed when meat and fish are grilled over open flame. Notably, maximum PAH formation occurs when the meat is 6-7 cm from the flame. Less PAH formation has been determined in electric ovens or grills. Over 20 PAHs have been identified in food and more than 10 have been found to have carcinogenic effects in experimental animals. Some PAHs ingested through respiration and skin have been found to have carcinogenic effects on the lungs and skin, while others have shown tumour-forming activity.

2. Heterocyclic Amines

Heterocyclic Amines are compounds formed during thermal processing of proteins containing glutamic acid, phenylalanine, ornithine or soya globulin. The formation of heterocyclic amines during cooking of protein-containing food varies depending on the food structure, cooking method, time and temperature. When the final temperature applied to food is below 150°C, heat degradation products of amino acids form in lower amounts compared to high temperature. More than 16 mutagenic HAs are known to form during meat cooking. Most of these have been found to be carcinogenic in mice. Individuals at cancer risk are affected by factors such as genetic predisposition, degree of exposure to substances like HAs and the inability of DNA to repair itself.

3. Acrylamide

Acrylamide is formed when certain amino acids and sugars present in fried food undergo the Maillard reaction. The major amino acid responsible for acrylamide formation is asparagine. It has been determined that acrylamide formation depends on temperature and duration and that the ambient temperature must exceed 120°C for acrylamide formation to occur. When ambient temperature is 160-180°C, acrylamide formation reaches its highest level. The much higher amounts of acrylamide detected in potato crisps and fries and cereal-based products compared to other foods are thought to be related to the high asparagine content of these products. Acrylamide has carcinogenic, mutagenic and reproductive toxic effects. The toxic effect of acrylamide on the nervous system of humans and animals and on the reproductive organs of male experimental animals is stated to appear after a single oral dose. In assessing acrylamide intake, polyacrylamides used not only in food but also in the cosmetics industry, food packaging and water treatment should be taken into account.

4. N-Nitroso Compounds

N-nitroso compounds can be formed from both nitrite and nitrate as a result of various biological processes in humans and animals, and also form during the curing stage of food. The main sources of N-nitroso compounds are cured meat and fish and certain cheese varieties.    

Curing:

Curing is the transformation of meat colour to permanent meat colour using K or Na salts of nitrite or nitrate. The highest levels of N-nitroso compounds are formed in meat cooked by frying method. N-nitroso compounds are toxic, teratogenic, mutagenic and carcinogenic; they cause DNA damage and gene mutation in different parts of the human body. Derya Dikbıyık / Chemist, Class B Occupational Safety Specialist / Hazardous Materials Safety Consultant Training Coordinator / TİGUDER