Transfer of milk fatty acids to Pecorino Siciliano cheese

Abstract

In previous studies it was observed that milk fatty acid (FA) composition is mainly affected by diet, and when ruminants graze pasture the percentages of polyunsaturated FA and conjugated linolenic acid (CLA) are higher than in milk from preserved forage. The maintenance in the cheese of the beneficial FA profile of milk from grazing ruminants is advisable. Little number of study exists concerning the effect of milk processing conditions on cheese FA profile, but no study was done with regard to Pecorino Siciliano cheese. The aim of this study was to evaluate the transfer of FA from ewes milk to cheese manufactured according to the Pecorino Siciliano technology, in order to verify if the cheesemaking process could modify the FA profile of cheese, as yet observed by other authors for CLA and C18:1 isomers. Bulk milk from Comisana ewes grazing a spring pasture was processed six times during three consecutive weeks. For each cheesemaking, the 48-h bulk milk was divided equally, one part was processed as raw milk and the other one was pasteurized (72°C for 20 s) and inoculated with a starter culture. FA transfer from milk to cheese did not seem to be greatly affected by cheesemaking technology also when milk was treated by pasteurization. However, some significant differences were recorded for C11:0 (P=0.0434) and C14:1c9 (P=0.0132) that resulted higher in cheese than in milk. Also some isomers of CLA, such as C18:2 t-9, c-11 and CLA C18:2 t-11, t-13, resulted higher in cheese than in milk (P=0.058 and P=0.0058, respectively), but the difference reached the significance only between milk and cheese from raw milk, probably as consequence of a different activity between natural microflora and added micro - organisms. This trial showed that during the cheesemaking the totality of milk FA are transferred into the cheese even when the milk is processed after a thermal treatment. Nevertheless, some variations had been observed with regard to CLA isomers, in line with other findings on sheep cheese produced in other Italian regions.