Alphas1-casein, milk composition and coagulation properties of goat milk

Amounts of alphas1-casein (as1-CN), protein, fat, SNF and total solids were measured in 125 goat milk samples. Coagulation time, coagulation rate and curd ®rmness were measured in 75 goat milk samples by dynamic mechanical analysis using a Bohlin VOR Rheometer. After adjustments were made for month, time of milk collection and animal age, it was con®rmed that goat milk with high percent total solids, SNF, fat and protein coagulated faster (high coagulation rate) and formed a ®rmer curd than milk that had lower levels of milk components. Coagulation was delayed (long coagulation time) in milk with high protein but resulting curds were ®rmer than curds made from low protein milks. Amount of as1-CN was positively correlated with milk components and coagulation time. Goat milk that lacked as1-CN had lower percentages of milk components and poorer coagulation properties than milk that contained as1-CN, suggesting that the presence of as1-CN in milk should improve coagulation properties. However, percent total solids, SNF and protein were more highly correlated with coagulation properties than as1-CN. Thus, measuring total solids, SNF or protein may be more practical in predicting cheesemaking potential of goat milk than measuring as1-CN, which is more tedious and expensive. Milk from Nubians and Nubian Alpine crosses contained a higher amount of as1-CN and other milk components, and exhibited higher coagulation rate and curd ®rmness than milk from Toggenburgs and Saanen Alpine crosses. Selection of goats with high solids, particularly Nubians, is recommended if cheese-making is the objective. # 2000 Elsevier Science B.V. All rights reserved.