Testing for Chemical Contaminants in Foods

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Food testing laboratories test foods for all kinds of contaminants whether, pathogens like bacteria, residues of antibiotics, pesticides or other chemical contaminants to ensure food safety.

Chemical contaminants can creep into food from a number of sources and pose a health problem. Food safety testing programmes analyse foods for chemical contaminants to ensure they are within food regulatory limits. Modern food testing laboratories have the equipment and technicians to detect chemical contaminants even at very low levels of concentration. Another important aspect is that they can even identify unknown or new chemical contaminants.

Sources of Chemical Contaminants in Food

  • residues of fertilizers and pesticides
  • residues of veterinary drugs
  • from environmental sources like water, air or soil pollution
  • cross-contamination or formation during food processing
  • migration from food packaging materials
  • presence or contamination from natural toxins
  • use of unapproved food additives and adulterants

Food testing laboratories approved for chemical testing of foods test food samples to ensure that foods are free of all chemical contaminants or they are present within the limits permitted by the Food Safety and Standards Authority of India (FSSAI). However, maximum residue limits of pesticides and other chemical contaminants, approved in one country may not be the same in another country. Therefore, food testing labs need to have approval of international bodies as well, so their food testing report is acceptable to all countries where the food products are exported.

Foods of animal origin are often tested for antibiotic residues because certain antibiotics can cause allergenic reactions and others can make humans resistant to them, if they are consumed frequently in foods; so all foods of animal origin need to be tested. Foods are also tested for heavy metals, use of unapproved food additives and deliberate adulteration. All these chemical contaminants can be carcinogenic and can affect the internal organs and remain lodged in body tissues. Some contaminants like polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) other persistent organic pollutants (POPs) have been banned for years, but they remain in the environment due to their high stability.

Food Processing Contaminants

Chemical toxins can be formed in foods during processing like heating, baking, roasting, grilling, canning, hydrolysis or fermentation. Nitrosamines can be formed by interaction of natural food components with food additives. Carcinogenic and genotoxic chlorpropanols, such as 3-monochloropropane can be formed during the acid hydrolysis of wheat, soya and other vegetable protein products, PAH can be found in grilled and smoked products, ethyl carbamate in yeast-fermented alcoholic beverages and other products or furan in heat-treated foods like coffee and canned food.

Food packaging contamination and identification of unknown chemicals

Direct contact of foods with packaging materials can result in chemical contamination caused by migration of certain substances into foods like bisphenol A or phthalates from plastic materials, 4-methylbenzophenone and 2-isopropylthioxanthone from inks. Detection and identification of unknown contaminants can be difficult if they are present at low levels. Only food testing laboratories that have expertise and good analytical strategies will be able to carry out thorough food testing for all kinds of chemical contaminants.