Protein polymorphisms and coagulation properties of Cilentana goat milk

Eighty-six Cilentana milking goats in four herds were selected to study protein polymorphism of αs1-casein and its association with chemical composition and coagulation properties. Four alleles (designated A, B, E and F) and nine genotypes of αs1-casein were detected. The BF genotype was the most frequent (32.6%), followed by EE (15.1%) and AF and BB (10.5%). The F allele showed the highest frequency and it negatively influenced cheese-making, as it was associated with a low αs1-casein content. Goats with the AB genotype produced milk with higher total solids, protein and fat content compared with the FF genotype (P < 0.05). Moreover, milk from the AB genotype had a lower enzymatic phase duration (T) and a higher coagulation speed (K20) than the BB genotype (P < 0.05). Curd consistency (a), detected at 10, 20 and 30 min from start of coagulation was higher for milk from the AA genotype, when compared with the EF genotype (P < 0.05). All the chemical and cheese-making characteristics varied with herd and months. Milk obtained in the morning showed better coagulation properties: higher coagulation speed and curd consistency. The genetic improvement of Cilentana population could be carried out using goats with genotypes AA or AB at the αs1-casein locus in order to increase casein content and milk coagulation properties.