CHANGE OF FLAVOUR IN STORAGE BUTTER.

Otago Witness, Issue 3100, 13 August 1913, Page 18

CHANGE OF FLAVOUR IN STORAGE BUTTER.

The United States Department of Agriculture has made an attempt to determine the part played by certain factors influencing the change of" flavour in butter in coo) storage. This matter is of considerable importance to Now Zealand. The following conclusions were reached :

1. A perfected method of analysis employed gave no evidence ot an increase in soluble nitrogen in butter on long standing at Odeg F., even when the conditions of the manufacture were most favourable to such changes. 2. Butter milk from sweet, unpasteurised cream and from sweet pasteurised cream when preserved with 18 per cent, sodium chloride to correspond to butter-curd solution, showed no proteolysis during a long period in cold storage. 3. Butter made from sweet pasteurised cream kept much better than butter made from similar crcain without pasteurisation, but the changes in the unpasteurised cream butter could not be reproduced by re-inocu-lating the pasteurised cream with the bacteria of the cream before 'pasteurisation. 4. About 10 per cent, by volume of fresh butter is gas, consisting approximately of nitrogen (by difference) 33 per cent., oxygen 20 per cent., and the remainder of gases absorbable by sodium hydroxide. The oxygen was materially less After storage. 5. The addition of iron to cream even in as small an amount as one or two parts per million parte of cream had an influence on the flavour of the butter, There was nothing to show that the nature of the flavour was appreciably changed, but the rate of development was accelerated. 6. Cream mav take up iron in quantities sufficient to affect the flavour from rusty cans, or even from the exposed bolt heads or other metal parts of the churn. 7. The action of copper is similar, but perhaps more intense. 8. It was found that in milk to which 18 per cent, sodium chloride had been added there was no change in the lactose when iron was added and a current of oxygen nassod through the milk for 72 hours. 9. A strong -odour may be produced in milk by the addition of small amounts of iron salt's.