EFFECT OF AA, EE AND FF GENETIC-VARIANTS OF CAPRINE ALPHA-S1-CASEIN ON CHEESE YIELDING CAPACITY OF MILK AND SENSORY PROPERTIES OF TRADITIONAL CHEESE

The caprine alpha(s1)-casein polymorphism is associated with different levels of protein synthesis. Some alleles (A, B, C) are associated with a 'high' level of alpha(s1)-casein (around 3.6 g/l), the allele E is associated with a 'medium' level (1.6 g/l) and the D and F alleles with a 'low' level (0.6 g/l). The aim of this work was to determine the effect of this polymorphism on milk composition and cheese yielding capacity and on the characteristics of ripened traditional cheeses. Ninety-nine batches of goat's soft cheese were made comparing the milk of alpha(s1)-Cn(AA), alpha(s1)-Cn(EE) and alpha(s1)-Cn(FF) goats of the same herd (milks A,E,F respectively). On an annual average, the milk A had higher protein, casein and fat content than the milk E, itself richer than the milk F. The casein/protein ratio of the milk A was also higher than the milk F one during the whole lactation period but the difference was lower in spring. The milk E was intermediate. The fat content of the milk A was also increased but less than the protein content. Due to the higher protein and fat contents, the higher casein/protein ratio and the better milk protein retention in curd, the cheese yield was proportionally increased: the mean differences between A and E and between A and F fresh cheese yields reached 8.2 and 17.7% respectively. Cheeses made from milk A were less fat, firmer and had a less intense characteristic 'goat flavour' than the E and F cheeses, the last difference being more marked in summer and autumn.