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Preliminary Evaluation of the Influence of Pasture Feeding on Proteolysis of Ragusano Cheese

Vincenzo Fallico 1, Lina Chianese 2, Stefania Carpino 1, Giuseppe Licitra 1,3

1- CoRFiLaC, Regione Siciliana, 97100 Ragusa, Italy
2- Department of Food Science, University of Naples, 80055 Portici, Naples, Italy
3- Department of Agronomic, Agrochemical Sciences and Animal Productions, University of Catania, 95100 Catania Italy

Abstract

The influence of native pasture for cows feeding on the levels and prfiles of proteolysis in Ragusano cheese at different ages (1,120 and 210 days) was evacuate through a comparison with the Total Mixed Rations (TMR) feeding. Eight experimental cheeses were produced from milk of cows consuming TMR diet supplemented with native pasture and eight control cheeses from milk of cows fed with only TMR. Cows diet was found to have no significant (p>0.05) impact on the overall composition of Ragusano cheese, including the levels of primary and secondary proteolysis measured as soluble N in acetate buffer at pH 4.6 and 12% trichloroacetic acid, respectively. Experimental and control cheeses showed similar extents of casein hydrolysis by urea-PAGE analysis and the densitometry of the electrophoretic profiles confirmed that nonsignificant differences (p>0.05) in bands intensity existed between experimental and control cheeses. These results suggested that the feeding strategy had no influence on the activity of proteases from rennet, milk and proteolysis, influencing the composition of the 12% trichloroacetic acid-soluble peptide fraction of Ragusano cheese. Experimental and control cheeses showed different peptide profiles by reserved phase-HPLC analysis and the information provided by these profiles were useful in discriminating cheeses based on age and feeding treatment by principal components analysis. Proteases of microflora derived from local pasture probably produced soluble compounds that were specifically present in the peptide profiles of experimental cheeses. Further studies will concern the molecular characterization of the different peptide fractions of experimental and control cheeses.

Keywords: Ragusano cheese, pasture, proteolysis

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