INFLUENCE OF GENETIC-POLYMORPHISM OF CAPR INE ALPHA(S1)-CASEIN ON PHYSICOCHEMICAL AND TECHNOLOGICAL PROPERTIES OF GOATS MILK

The present work aimed to study the effet of alpha(s1)-casein genetic variants on physico-chemical characteristics, cheese-making properties , and heat stability of goat's milk. The study was based on an analysi s of 153 individual milk samples which were obtained from 3 types of g oats homozygous at the alpha(s1)-Cn locus: AA, EE and FF (51 samples o f each type). Results showed that genotype had a very significant effe ct (AA > EE > FF) on fat, total nitrogen, protein and casein content, and on casein number (casein N/total N). Whereas alpha(s1)-casein type had a limited effect on mineral and salt equilibria, it had a marked influence on micellar size (AA < EE and FF) and to a lesser extent on micellar mineralization. As far as technological properties were conce rned, the most important differences were observed with rennet gel str ength (AA > EE > FF) and gel strengthening rate (AA > EE and FF). Micr o-scale cheese-making carried out on 23 small bulk milks showed that d ry matter and nitrogen recovery coefficients were 4 to 5% lower in FF than in AA milks. On the other hand, no difference was found in heat s tability between the 3 types of milk.