The effect of β-lactoglobulin phenotype on the content, composition and properties of fat in milk, and the manufacture and properties of butter

The influence of beta-lactoglobulin (beta-Lg) phenotype on the content, composition and properties of fat in milk was determined. A study of individual cows indicated that the solid fat content of the milkfat at 10 degrees C was independent of the beta-Lg phenotype. Bulk samples from a mixed herd of 200 beta-Lg AA and 200 beta-Lg BE phenotype cows was characterized at two collections 3 weeks apart. The percentage fat content of the milk from the beta-Lg BE phenotype herd was 9% higher than that from the beta-Lg AA phenotype herd. However, the detailed milkfat composition of the two herds was similar in solid fat content, fatty acid content, and total colour. Manufacture of butter in a batch churn produced butter of similar sectility hardness and similar free fatty acid and peroxide value content. These results suggest that the properties of the milkfat are not significantly affected by the variant type. It was noted that there may be minor differences in flavour as the butter produced from the milk of the beta-Lg BB phenotype herd exhibited a "cooked-biscuity" flavour in one instance.