Dosage des acides gras libres

Abstract

Lorsqu'on étudie les lipides des produits laitiers on se trouve souvent en présence d'un mélange de glycérides et d'acides gras libres.

Lipolytic Enzymes and Hydrolytic Rancidity in Milk and Milk Products

“…However, such methods tend to be tedious and time-consuming and are suitable only as reference methods. 343 For routine analyses, methods of types 1 and 2 are usually employed.…”

“…343 In fact, acidification of milk greatly enhances the sensitivity of organoleptic detection of lipolysis in milk. 35U57 The detection of rancidity is reduced by the association of the FF As with certain proteins in milk358.359 and by heating of milk.351 The phase with which the fatty acids associate also influences their flavour threshold, since the short -chain acids have much lower thresholds in fat than in water, while the opposite applies to the long-chain acids.…”

Some monomethyl‐branched fatty acids from ruminant fats: Open‐tubular GLC separations and indications of substitution on even‐numbered carbon

“…This in turn should affect the level in ruminant plasma (30), but propionic acid appears to be approximately as important as butyric acid in both cow and sheep plasma (30). There is a tentative identification of propionic acid in human milk (4). We therefore feel that propionic acid incorporation into fatty acids provides an adequate basis for our hypothesis on the origin of these monomethyl-branched acids in fats of ruminants, and that the concept could be extended to humans as a source supplementing intake of preformed monomethyl-branched fatty acids from dietary sources.…”

“…Ruminant fats are notorious for the complexity of the mixture of fatty acids from which they are constituted (1)(2)(3)(4)(5). In recent years the three important isoprenoid acids 4,8,12-TMTD (=4,8,12-trimethyltridecanoic), 2,6,10,1 4-TMPD (= 2,6,10,14-tetramethylpentadecanoic or pristanic) and 3,7,11,15-TMHD (=3,7,11,15-tetramethylhexadecanoic or phytanic) have been recognized as important among the unusual fatty acid components and thoroughly documented (6)(7)(8)(9)(10).…”

Zur Lipolyse der Milch durch technologische Beeinflussungen 1. Mitt. Stand der Kenntnisse und Untersuchungen zur Beeinflussung von Milch und Rahm durch Pumpen

“…Milchprodukten gibt KUDZAL-SAVOIE[72]. Aufgrund der kurzen Untersuchungszeit wird oft den Extraktionsverfahren der Vorzug gegeben.Beim Gehalt an freien Fettsiuren findet man in der Literatur auch oft Angaben in mval/l Milch.…”