EXPORTING PROBLEM

Hokitika Guardian, 13 September 1932, Page 6

EXPORTING PROBLEM

BUTTER-FAT DETERIORATION

EATS "AND THEIR CHANGE

WELLINGTON, (September. 12

As it is now generally believed that the life and flavour of most foods are determined mainly by the fat, the investigation of changes in stored fats, is becoming of increasing interest, said Mr C. R. Barhicoat, M.Sc., in a paper read to a recent meeting of the Wellington branch of the New Zealand Institute of Chemistry. •After stressing. flhei fact that fats entered largely into the composition of New Zealand food exports, (Mr Banniooait said that one change in stored fats was due to hydrolysis, whereby free fatty acids were liberated. Fats in the tissue contained natural lipases which caused the rapid development of acidity by hydrolysis.- M°lt .fats were graded commercially by their acid values, a higher value denoting poor fat. Another change—oxidation rancidity —gave rise /to the Itypieal. tallowy odours of old fats, and wag commercially the most common, type, if deterioration encountered. Unsaturated fats even, at low temperatures tended to combine with ibhe oxygen of the air, giving fat peroxides, and it was in the degradation products of thes e peroxides that undesirable rancid flavours would be found.

Other changes were bleaching and yellowing. Bleaching occurred in butter, for instance, wherp fats naturally yellow in colour might Idee their natural tint, eventually .showing a sickly colour, particularly Jfd exposed surfaces.

Some fats, normally white, tended to discolour to a yellow; colour in storage as in the case of frozen fish and r» Gbits, the higher unsaturated fatty acids being responsible for this change. “Fishiness” was an oxidation defect io fish o ills ,. bacon, and other fats, containing higher unsaturated acids.

Fishiness in butter had been shown to be. due to the hydrolysis of lecithin by acids, which was accelerated by the high acid contents of ripe butter. Unfortunately ripe butters, were, wanted in Great. Britain, and New Zealanders were not yet able to export them owning to their tendency to fishiness. The Danes were able to. do so, and their butter always secured a fair premium over that from New Zealand. Good fresh butter, said tlie speaker, derived its flavour from diacetyl, which was progressively lost during storage.

Great difficulties bad been encountered in finding suitable containers for butter which would not impart woody taints, etc., to the fat. Factors promoting rancidity were the effect of moisture, light, temperature, the cata- . lysing effect of metals, and exposure to air; therefore fats kept in cold storage in hermetically sealed containers, in a vacuum, in inert gas and free of moisture would keep indefinitely. ! This, of course, was not possible in | practice. .