Wednesday, October 29, 2008


Threat of food contamination from the field or due to processing artifacts has been exercising the minds of the consumer ever since food production and processing became more organized and commercialized. With increasing demand for better quality food in sufficient quantities, the agrofood industry has not spared any efforts to meet the challenges by deploying many new technologies to improve quality, safety and nutrition. But there are many imponderables and contingencies that affect the safety of foods from time to time. The undesirable effect of trans fats which was never anticipated when hydrogenation technology was adopted is an example of how newer knowledge helps to unravel threats from unexpected quarters requiring timely and adequate precautions to overcome them.

A potential threat of recent origin is that posed by Acrylamide ( also known as acrylic amide or 2-propenamide) which has become an international issue with many countries trying to assess the damage it can do to their consumers. Thanks to the diligence of Swedish food scientists, many foods were found to be containing high amounts of the chemical Acrylamide, an artifact generated in the food due to thermal processing at temperatures beyond 120 Celsius. Higher the temperature of processing, larger will be the levels of this chemical present in the final product. In the migration test for food grade plastics, an upper limit of 0.01 mg /kg of food is accepted internationally and in water a maximum of 0.5 parts per billion (ppb) is allowed as an inadvertent contamination from the polyacrylamide resins used for purification. So far these are the standards in force but with foods reported to contain levels several fold higher, it has become a vexing problem for food safety agencies to come up with a figure as safe limit that can be permitted in foods. The problem assumes critical importance as 30% of calories derived by an average consumer in Europe and USA come from foods containing acrylamide.

There is no unanimity regarding the levels of Acrylamide that can be consumed and the figures vary from 1.2 ug to 41 ug per day per person. It is estimated that acrylamide causes several thousand deaths every year though such claims are not substantiated by authentic documentation. What is known is that this chemical at 0.5 mg per kg of food taken causes neuropathy and at 2 mg level leads to infertility as reported by FAO-WHO. Acrylamide is implicated in diseases like cancer in rats and tumors in nervous system, oral cavity peritoneum, thyroid gland, uterus and mammary glands. Foods like potato chips contain Acrylamide at levels varying from 1096 ppb to 3700 ppb while in French Fries levels of 216-606 ppb Acrylamide are reported. Some of the popular foods in developing countries were reported to contain Acrylamide as high as 5000-6000 ppb. The presence of this chemical is reported in baked foods, cereals, coffee and others also, though the concentration is not very high. Use of excessively heated oils for frying and higher pH foods develop increased levels of Acrylamide and these findings are highly relevant to India where hundreds of traditional sweets and snacks are prepared under uncontrolled heating regimes. Unfortunately no reliable data is available in India regarding Acrylamide in these foods. All foods containing the amino acid Aspargine and Glucose are vulnerable to formation of acrylamide during cooking at temperatures above 120C.

The State of California in the US, recently indicted four major snack makers-Heinz, Frito Lay, Kettle foods and Lance Inc for $ 3 million for marketing their products containing high levels of acrylamide and is forcing the industry to reduce the level of acrylamide to safer limits in the interest of the consumers. Such efforts are likely to be emulated by others and eventually new technologies may emerge to make food products free from this undesirable artifact. Already it is known that in Fries made at 175C, the acrylamide concentration was only 300 ppb which increased to 1100 ppb when frying temperature was raised by just 5C to 180C. The Chinese scientists found that a pre-frying step of dipping in bamboo extracts dramatically reduced formation of acrylamide while use of commercial enzymes like 'Acrylaway' and 'PreventAse', two enzymes capable of converting Aspargine into aspartic acid and consequently preventing the amide formation, are being recommended. Use of fresh potatoes or curing of cold stored potatoes or washing of cut potatoes before frying reduces glucose content and consequently the acrylamide formation also.

Whether it is in the house holds or in the commercial kitchens, there is always a tendency to fry at high temperatures, the major objectives being, faster frying, lesser oil uptake and crisper texture. Now one can understand clearly the consequences of fast frying at high temperatures which, besides causing increase in Acrylamide in many foods, can also cause oil deterioration contributing to generation of oxidized and polymerized break down products considered undesirable for health. Though it is scary to think of an Acrylamide driven catastrophe, one can derive some solace from the fact that the threat perception is based on animal experiments using Acrylamide at doses 100000 times higher than the levels found in foods and hope Acrylamide may not be as dangerous as imagined in human system


No comments: