TAINTED MILK

Otago Daily Times, Issue 27092, 28 May 1949, Page 2

TAINTED MILK

THE FARM

VARIETY OF CAUSES INCORRECT FEEDING METHODS It is impossible completely to remove bad flavours from milk once they have been absorbed. It is possible to remove them only partly, by efficient aeration and cooling, and to control further development to some extent by pasteurisation. Animal foods play an important part in flavour. Certain foods impart characteristic odours and tastes to freshly-drawn milk. Thus turnips, swedes, cabbages, rape, kale, chou moellier, green maize, millet, clover, lucerne, beet roots and tops are common causes of offtflavour, especially when unskilfully fed. Aeration and cooling (over an open corrugated cooler) will help to remove the trouble, but will not do so entirely. Feed flavours can easily be prevented in the case of supplementary feed by carefully limiting the amounts of such feed and by ceasing that feeding at least four hours before milking. Silage is sometimes a source of trouble, especially if made from clover or lucerne, or when it is badly made, mouldy, or decomposed. Well-made grass silage, fed out carefully after milking, will give little trouble. Careless feeding out, so that pieces of the silage find their way into the milk from the coats of the cows or the clothes of the milkers, is frequently responsible for this taint. Certain weeds also impart objectionable flavours to milk. In New Zealand land cress, water cress, pennyroyal, buttercup, and ragwort are the worst offenders. Feed flavours frequently become worst as the milk ages, particularly in association with dirty milking methods, high bacterial contamination, or neglect of efficient cooling and aeration. Foreign odours are often absorbed from the environment. Unclean sheds and surroundings give rise to bad smells which are readily absorbed by newly-drawn milk. Bacteria which gain entrance to the milk after it has been drawn from the cow are the most common and serious cause of flavour defects. Contamination may arise from the cow’s coat, dung, dirty machines and utensils, from the water supply and from the hands of the milkers. Contaminating substances such as soap left in the milk bucket and soda or other materials not properly removed by washing before machines or milk vessels are used, also impart taints to milk. Absolute cleanliness, cooling of milk and cream to at least 60deg F. immediately after milking, and maintenance at that temperature until used, are preventive measures.