Tuesday, November 18, 2008


Pathogenic microorganisms causing various diseases by infecting foods are of major concern to the food industry and food handlers in general. While pathogens require a certain minimum moisture in the medium where they can thrive, insects and pests bring about huge losses in dry commodities like cereals, pulses, plantation crops and nuts and seeds. Pasteurization techniques widely used in fluid foods take care of pathogenic infarctions and consequent risk to human lives and UHT and Aseptic processes have proven to be highly dependable to ensure freedom from pathogenic out breaks during the last 2-3 decades. High pressure sterilization, irradiation, ultra filtration all achieve microbial destruction to varying extent. The production environment and practices prevalent in a country determine the microbial quality of the produce and commodities raised there and food poisoning from endotoxic and exotoxic microbes is reported to be widespread though no reliable statistics are available to confirm or deny such claims. Since microbes are not visible to the naked eyes, natural and accidental contamination and consequent mild manifestations go unnoticed and unreported. Imagine the size of a pin head where 2.5 lakh cells of the lethal strain of E.Coli can be packed and only 10-50 cells can be fatal to children and old age population. Other important deadly microbes that infect many foods include Salmonella, Clostridium parfringens, Bacillus cereus, C. bottulinum and Listeria.

Insects and pests constitute a major threat to food supplies all over the world and they destroy foods both in the field and at post harvest stages. Some estimates put the loss of food grains, most susceptible to infestation at 40% of world production valued at billions of dollars. There are innumerable species of insects in this planet numbering 6-10 million, on a conservative estimate though no one knows their exact number. Imagine their population in this world that will be in trillions! About 1% of these only are considered to have pest value to the human beings, competing for food and consequent food losses.

Rural folks rarely understand the severity of the problem as infestation does not reduce the volume of the grains but the weight loss results due to insects carving out nutrients from the grain without showing any signs outwardly. Besides the insects leave their body parts after their life cycle and the excreta during their proliferation. High uric acid content is often associated with severe infestation. Secondary microbial infection also takes place further deteriorating the safety of the affected grains. Use of synthetic chemical insecticides is inevitable both in the field during plant growth and during storage if food grains are to be saved or spoilage reduced to manageable limits. Residual pesticides, in turn, pose dangers to the consumers which gave rise to the birth of the organic food industry. Biopesticides are also receiving attention for use in place of toxic pesticides currently being used in large quantities.

Heating any food at 130C for 30 minutes, storing under 0C temperature for 4 days, use of gamma radiation, many traditional practices like mixing with clay, use of neem leaves and underground storage, modern modified atmospheric storage etc are known to counteract infestation problems to varying extent depending on the food material and the storage environment. Entolators are part of flour mills to eradicate infestation in wheat and wheat products.

Infrared radiation (15-1000 micrometer wave length) is the most recent tool recommended for disinfection and dis-infestation. It can kill pathogens like Salmonella in almonds and some of the dry foods and is found to be effective in killing insects, their eggs and larvae in many crops such as rice. Food industry is taking a leaf out of the experience of auto industry which had to switch over to water based paints for environment safety and drying the paints using infrared efficiently. Infrared wave length has an affinity for water. Insects, eggs and larvae and microorganisms have higher moisture content than the grains or flours and the infrared radiant energy targets the water in these vectors. The rapidly absorbed radiant energy from infrared waves heats up the live contaminants killing them in seconds. Food industry already uses infrared radiation for drying and roasting food materials and same facilities can be used for disinfection and disinfestation also in many dry ingredients.


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