WESTERN BLOTTING OF NATIVE AND DENATURED BOVINE BETA-LACTOGLOBULIN TODETECT ADDITION OF BOVINE-MILK IN CHEESE

Western blotting of bovine beta-LG is a valid method to detect adulter ation by pasteurized bovine milk, by UHT bovine milk, or by heat-denat ured bovine whey proteins in cheeses made of milk from other species. Use of PAGE of whey or isoelectric focusing of beta-LG isolated from t he casein fraction was followed by immunodetection with anti-bovine be ta-LG antiserum. The selectivity of the antisera to react with native and denatured beta-LG was studied. Detection limits of native and dena tured beta-LG standard solutions were 10 and 50 pg/mu l, respectively. Immunoblotting of the native-PAGE plates of whey proteins from cheese allows detection of bovine heat-denatured whey proteins or pasteurize d bovine milk added to cheese even at <1%. At <1% adulteration by UHT milk immunoblotting of the isoelectric focusing plates of beta-LG isol ated from casein micelles is a better detection method. Adulteration w ith bovine milk or denatured whey proteins in percentages >1% can be d etected by either Western blotting methods.