New insights in goat breeds of Ethiopia: High content of αs1-CN and its association with coagulation properties, whey syneresis and micelle size

Milk from 94 Ethiopian goats (four breeds) was assessed for casein level, micellar size, coagulation properties and whey syneresis to evaluate cheese-making potential. Casein content (g/kg) ranged from 6.84 to 8.94 (alpha(s1)); 4.16-4.98 (alpha(s2)); 12.51-15.37 (beta) and 6.89-8.93 (kappa). Arsi-Bale goats had the highest alpha(s1)-casein (8.94 g/kg) followed by the Somali goats (7.90 g/kg); and were higher than Boer (7.05 g/kg) and Cross (6.84 g/kg) (P < 0.001). Milk from Arsi-Bale and Somali goats had significantly (P < 0.05) smaller micelles; 207.47 and 209.29 nm respectively than Boer (230.30 nm) and Cross (228.71 nm). Significantly stronger gels (P < 0.05) were obtained from milk samples with higher alpha(s1)-CN level and smaller micelles (Arsi-Bale 37.99 mm and Somali 36.19 mm) than samples with lower alpha(s1)-CN level and larger micelles (Boer 31.13 mm and Cross 33.51 mm). Syneresis was significantly higher (P < 0.001) in milk with good coagulation properties. Curd firmness was negatively correlated with coagulation rate (R, -0.832) and micellar size (R, -0.647). Milk from Arsi-Bale and Somali goats had significantly higher alpha(s1)-CN level, smaller micelle and better cheese making property than the cross and Boer goats. This study shows that there exists high potential among indigenous goats for cheese production. (C) 2014 Elsevier B.V. All rights reserved.