[Study of lipid and protein fractions of a Sardinian cow cheese - the Peretta]

Cengarle, L.; Tilloca, G. . Dipartimento di Scienze Fisiologiche, Biochimiche e Cellulari; Carta, A. . Dipartimento Farmaco Chimico Tossicologico; Manca, R.; Pinna, L.

[Study of lipid and protein fractions of a Sardinian cow cheese - the Peretta]

2002

Cengarle, L. | Tilloca, G. (Sassari Univ. (Italy). Dipartimento di Scienze Fisiologiche, Biochimiche e Cellulari) | Carta, A. (Sassari Univ. (Italy). Dipartimento Farmaco Chimico Tossicologico) | Manca, R. | Pinna, L. (Istituto Tecnico Industriale Statale G.M. Angioy, Sassari (Italy))

To study the changes of the lipid and protein fractions in a Sardinian cow cheese (Peretta) during the ripening, we have acquired, immediately after the salting, 12 whole cheeses of artisan Peretta, stored in suitable rooms, taking a cheese at pre-arranged times up to 55 days. To compare obtained data, we have utilized 18 analogous samples, already ripened, of Sardinian commercial Peretta. For each sample we have determined: peripheric and central% of water content, total lipid%, NaCl%, fatty acid composition%, saturated, monounsaturated, polyunsaturated fatty acid ratio, unsaturation/polyunsaturation ratio by 1H-NMR spectrometry and comparison with GLC data, glyceridic form distribution by TLC and densitometry. Furthermore, the proteic fraction insoluble at pH 4.6 has been extracted and submitted to ultrathin minigel electrophoresis and to densitometric analysis. During cheese ripening, an evident humidity decrease, with consequent lipid increase in eating portion percentage, has obviously occurred. At the same time, moreover, a light decrease of total fatty acids, particularly polyunsaturated (linoleic acid), expressed as g/100 g of dry matter, has been observed. Glyceridic forms ratios point out that in cheese lipids either degradation (beta-oxidation, decarboxilation) or neosynthesis occur; therefore, among the different fractions, only diglycerides generally increase; triacylglycerols and fatty acids vary complementarly. Along the ripening, an evident proteolysis of alpha S1 and k casein, lighter for beta casein, occurs

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