EFFECT OF KAPPA-CASEIN GLYCOSYLATION ON CHEESE YIELDING CAPACITY AND COAGULATING PROPERTIES OF MILK

The effects of the average degree of glycosylation of milk kappa-casei n on rennet-clotting time, rate of curd firming and curd firmness 30 m in after the addition of chymosin were measured on 55 blended-milks by a Formagraph. The degree of glycosylation, which is reflected by the N-acetylneuraminic content Of kappa-casein (NANA/kappa-CN) varied from 43 to 93 mug/Mg Of kappa-CN during the study. Significant (p < 0.01) variations in the rate of firming and curd firmness in relation to the NANA/kappa-CN ratio were observed, suggesting that a firmer curd can be obtained with milk having a high NANA/kappa-CN value. To study the effect of the degree of glycosylation of kappa-casein on cheese yieldi ng capacity, laboratory-scale Cheddar-type cheese was prepared from 45 blended-milks. No significant (p > 0.1) difference in the 37% moistur e-adjusted cheese yield was observed. It is concluded that the improve ment of the coagulating properties of milk brought about by the increa se in the average degree of glycosylation Of kappa-casein did not resu lt in a greater cheese yield.