Abstract:
Milk coagulation is the primary step in the development of most dairy products. Raw milk from individual cows and different
breeds exhibit distinct coagulation capacities. This variation is largely influenced by milk protein genetic variants. The aim of the
present study was to evaluate differences in coagulation properties between milk obtained from three cattle breeds/types found in
Sri Lanka. A total of 90 milk samples (400mL from each individual) were collected from two Sri Lankan cattle breeds/types
(Thamankaduwa White/TW and Local/”Batu” cattle) and one European cattle breed (Friesian). Collected samples were subjected
to enzymatic coagulation using commercial rennet source (Chymax, Christian Hansen Standard, Denmark) and lactic acid
bacteria (LAB) coagulation using a commercial starter culture(YFL 8 12,Christian Hansen Standard, Denmark) to determine milk
coagulation properties. Different properties of milk coagulum such as yield, curd firmness, syneresis and rheological properties
were evaluated. The biochemical composition (lactose, protein, fat, solid-non-fat) of milk samples were determined. Capillary
Zone Electrophoresis (CZE) method was used to determine milk protein genetic variants. Experimental design was Nested
Completely Randomized Design with three treatments. Milk coagulation time and curd firmness after enzymatic-coagulation
were not significantly different (p>0.05) among the breeds. Coagulum yield was significantly higher (p<0.05) for the TW type
than that of other breeds. Coagulum yield was negatively correlated with β-caseinA1 and α-lactalbumin in both enzymatic (-0.58)
and LAB coagulation (-0.69). Coagulum yield was positively correlated (p<0.05) with β-casein B variant (0.70), protein (0.34)
and lactose (0.36) contents. Meltability value was weakly and positively (p<0.05) correlated (0.34) with fat content of milk.
Overall results indicate that there is a significant correlation between milk coagulation properties and milk protein genetic
variants in three cattle breeds/types considered in the current study. TW type is the unique among studied breeds in terms of
coagulation properties and milk protein genetic variants.
