Natural born killers
DAIRY farmers in developing countries invariably face a major problem because if the fresh milk from a healthy cow is not cooled and does not reach the processor within five hours after milking, it is rendered unsuitable for processing. This results in loss of time, labour and valuable nutrition. But this problem has a cheap and a simple solution. And that is, to treat raw milk with its own anti- bacterial system created by nature for the benefit of the organism, says Jan Barabas, a dairy technician officer in the dairy group of the Food and Agriculture Organization's (FAO) Animal Production and Health Division, Rome (Dairy for Development, Vol 28, No 2).
Countries with advanced largescale dairy industry have on-farm facilities for cooling, storage and transportation of raw milk which help in controlling the bacteria count and preserving its quality. But in most developing countries, raw milk is invariably produced by small dairy farmers and immediate refrigeration and transportation to processing sites is technically and logistically impossible.
However, lactoperoxidase (LPS) offers a natural way of protecting raw milk from bacterial infection. LPS is a naturally occuring protein in milk and develops anti-bacterial properties in the presence of hydrogen peroxide and thiocyanate, also contained in milk. Studies have shown that small additions of hydrogen peroxide and thiocyanate activate LPS's bacteria- fighting mechanism, thus enhancing its shelf life considerably.
To activate LPS in raw milk, the natural level of thiocyanate in it is enhanced to about 15 parts per million (Ppm) and an equirnolecular amount of hydrogen peroxide (8.5 Ppm) is added. Toxicological studies have confirmed that modest levels of thiocyanate, as recommended, would pose no health hazards, argues Barabas. In experiments and field trials, the treatment produced an anti- bacterial effect that lasted for five to six days in refrigerated milk and increased shelf life of raw milk by three to four hours in an ambient temperature of 30'c.
"Effective, easy and safe to apply at the milk collection points, the method could be of immense use in countries with warm climate," says Barabas. "It provides a safety margin for delivery of unrefrigerated milk to processing centres, and also makes it possible to collect milk from remote areas where collection is not feasible at present. It also preserves the refrigerated milk for longer durations in areas which have refrigeration facilities," he adds.
The International Dairy Federation, says Barabas, has carried out its own studies and concluded that the LPS system is an effective alternative to refrigeration to prevent decline in the quality of raw milk. Field trials in Kenya, Nicaragua, Sri Lanka, Mexico, the Philippines and Cuba have also confirmed the merits of the LPS system. The FAo is now attempting to popularise this applied biotechnological process to benefit milk producers throughout the developing world.