Les acides gras libres du fromage

Abstract - The free fatty acids of cheese
The origin and the role of free fatty acids in matured cheese have been discussed.
The level of the free fatty acids (per weight of cheese) and the relative proportions of the different free fatty acids constitue specific characteristics according to the different types of cheese.
The authors propose a rather easy method by means of which it is possible to obtain the "complete spectrum" of free fatty acids present in a cheese sample.
The free fatty acids are obtained by extraction from acidified cheese and then transformed into soaps. After desiccation ff the soaps, the fatty acids are freed by acid hydrolysis. The volatile fatty acids are analysed directly by gas chromatography and the fatty acids with a higher molecular weight are also analysed by gas chromatography, but only after transformation into methyl esters.
The quantitative determination of all free acids is possible when using two acids, "internal standards", the one having a low molecular weight and the other a high molecular weight.
The authors show that by using the proposed extraction method one obtains a greater quantity of acetic acid than by the distillation method, however, it is not possible to state that the whole quantity of acetic acid has been determined.
The proposed method has been applied to the study of free fatty acids in different samples of the following cheeses: "Gruyère de Comté" and "Emmental" which are very different as far as the organoleptic quality is concerned

Résumé - Une méthode permettant l'obtention de l'ensemble des acides gras libres du fromage est décrite. La chromatographie en phase gazeuse (avec addition d'un étalon interne) permet le dosage quantitatif des divers acides gras.
Des exemples d'application à l'étude des acides gras libres de quelques Gruyère de Comté illustrent les possibilités d'investigations offertes par la méthode proposée