\beta-Lactoglobulin Variants in Awassi and Morkaraman Sheep and their Association with the Composition and Rennet Clotting Time of the Milk


Abstract: In this study, \beta-lactoglobulin (\beta-Lg) variants in Awassi and Morkaraman sheep were studied using polyacrylamide gel electrophoresis, and their association with composition and rennet clotting time of the milk was estimated. Two alleles (A and B) and 3 different genotypes for \beta-Lg (AA, AB and BB) were observed in the whey from both breeds. The frequencies of \beta-Lg alleles were estimated as A 0.63 and B 0.37 in the Awassi breed, and A 0.56 and B 0.44 in the Morkaraman breed. These results indicate high \beta-A frequencies in both sheep breeds. Significant relationships were obtained between \beta-Lg variants and some properties of the milk from both sheep breeds (P < 0.01). In the Awassi breed, milks with \beta-Lg BB had significantly higher fat content and lower lactose content, while milks with the same variant had higher protein and solid non-fat contents in the Morkaraman breed. On the other hand, milks with the \beta-Lg AA variant in the Awassi breed had a short rennet clotting time, while milks with this variant in the Morkaraman breed had the lowest value for rennet clotting time but the result was not statistically significant. Therefore, it could be concluded that milks with the BB genotype are of importance in terms of cheese technology.

Keywords: Awassi, Morkaraman, \beta-Lg, milk composition, rennet-clotting time

Full Text: PDF