OFF-FLAVOURS IN MILK MUST BE PREVENTED

Bay of Plenty Beacon, Volume 13, Issue 87, 16 May 1949, Page 3

OFF-FLAVOURS IN MILK MUST BE PREVENTED

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 an 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 offflavour, especially when unskillfully fed. Aeration and cooling (over an open corrugated cooler) wlil help to remove the trouble, but will not do so entirely.

Can Be Prevented 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. There is more difficulty where pastures are rich in clover. The best that can be done in such cases is to build up the soil fertility to obtain a better balance of grasses and clover, as extra fertility raises the percentage of grasses in the sward. During the buildingup process these paddocks should be grazed directly after milking and left vacant for at least four hours before the next 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, will give little trouble. Careless feedingout, 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.

Weeds Too Certain weeds also, impart objectionable flavours to milk. In New Zealand, land cress, watercress, pennyroyal, buttercup and ragwort are the worst offenders. Feed flavours frequently become worse 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 new-ly-drawn milk. Paint, engine exhaust gases and disinfectants—in fact, any volatile odours—can quickly affect the flavour. 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 60 degrees F. immediately after milking, and maintenance at that temperature until used, are preventive measures. Indigestion—-Sometimes

Off-flavours of bitter type in newly-drawn milk are sometimes due to a cow’s indigestion. Udder troubles, particularly mastitis, are responsible for unpleasant flavours. The milk of affected quarters has a disagreeable taste of a stale or somewhat salty nature, even though the appearance of the milk has not been affected and even when the trouble has apparently cleared up. Certain medicines given to cows under veterinary treatment may be detected in the taste of freshlydrawn milk. Application of smelling substances to udders or sore teats may also be a frequent source of taint.

Certain metals, too, may have detrimental effects on the flavour of milk which comes in contact with them. Thus copper and copper alloys such as nickel, brass, bronze, etc., rusty cans or other rusty surfaces are all alike harmful, producing a metallic or talowy flavour. Tallowy flavours are frequently a result of exposure of the milk to direct sunlight, such as may happen with milk bottles used in* town deliveries.