Portal de Periódicos da CAPES

Relationship of Fat Acidity to Rancidity in Homogenized Raw Milk

1944; Elsevier BV; Volume: 27; Issue: 3 Linguagem: Inglês

10.3168/jds.s0022-0302(44)92579-8

1529-9066

I.A. Gould,

Probiotics and Fermented Foods

The action of milk lipase on butter fat is generally believed to produce at least two detectable changes : first, the production of free fatty acids, and second, the production of rancid or rancid-like flavors.The production of the rancid flavor is attributed to free butyric acid and other lower fatty acids such as capric, caprylic, and caproic.Furthermore, the appearance of the rancid flavor is expected whenever milk fat undergoes lipolysis, indicating that the glycerides of the lower fatty acids are always attacked by lipase under normal conditions.Some efforts have been made to correlate the extent of fat splitting with rancid flavor development (1, 5, 7), but information on this relationship is byno means complete nor has it been applied to conditions in which the lipase activity is accelerated by homogenization.The amount of lower fatty acids liberated from butterfat by lipase action may be expected to be relatively small inasmuch as the glycerides of the lower fatty acids constitute a comparatively small portion of the total fat and, also, since the work of Willstatter and Memmen (10) indicates pancreatic lipase to have slight affinity for the lower esters.Although the quantity of the lower fatty acids involved in lipase activity is small, the effect of these acids on flavor may be marked.Grossfeld and Battay (3) observed butyric acid could be detected by smell when present in a ratio of 1:12,500.In the case of dairy products, the actual type of flavor produced by lipase activity may not always be well defined and may vary with conditions.Relatively slight lipase activity may result in flavor defects which are not typically rancid (4, 7).Results which have been reported showing the relationship between the acid degree of the fat (ml. of N NaOH per 100 grams of fat) and the rancid flavor in the original product from which the fat was obtained are not in total agreement.Fours (1) in his study of commercial butter, could find no direct relationship between rancidity of the butter and the acid degree of the butterfat.The acid degrees of fat from non-rancid butter ranged