OPTIMIZATION OF PROTEIN PRECIPITATION IN ACID WHEY OBTAINED FROM SMALL RUMINANTS MILK

Attempts to maximize the precipitation yield of the major proteins via thermal processing of whey obtained from milks of Portuguese native b reeds of ewes and goats was done using heating time, heating temperatu re, and stirring rare as independently manipulated variables. The expe riments were planned according to a full factorial design with eight c orner points, six axial points, and three replicated center points. As sessment of the fractions of beta-lactoglobulin and alpha-lactalbumin removed by precipitation was done by gel filtration chromatography. Th e loci of the values of each manipulated variable (when the remaining two are fixed) which lead to critical points were obtained for both pr oteins, and the nature of such points was found. Comparative evaluatio n of the various loci has indicated that maxima for the precipitation of alpha-lactalbumin and beta-lactoglobulin from both whey sources exi st. However, a maximum value for the selectivity of precipitation of b eta-lactoglobulin relative to that of alpha-lactalbumin (within physic ally realizable conditions and without extrapolation from the experime ntal range covered) exists only for goat's whey (at a temperature of c a. 92C, heating time of ca. 46 min, and stirring rate of ca. 79 r.p.m. ).