Western Blotting of Native and Denatured Bovine ß-Lactoglobulin to Detect Addition of Bovine Milk in Cheese

¹ Instituto de Fermentaciones Industriales (CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain

Western blotting of bovine ß-LG is a valid method to detect adulteration by pasteurized bovine milk, by UHT bovine milk, or by heat-denatured bovine whey proteins in cheeses made of milk from other species. Use of PAGE of whey or isoelectric focusing of ß-LG isolated from the casein fraction was followed by immunodetection with anti-bovine ß-LG antiserum. The selectivity of the antisera to react with native and denatured ß-LG was studied. Detection limits of native and denatured ß-LG standard solutions were 10 and 50 pg/µl, respectively. Immunoblotting of the native-PAGE plates of whey proteins from cheese allows detection of bovine heat-denatured whey proteins or pasteurized bovine milk added to cheese even at <1%. At <1% adulteration by UHT milk immunoblotting of the isoelectric focusing plates of ß-LG isolated from casein micelles is a better detection method. Adulteration with bovine milk or denatured whey proteins in percentages >1% can be detected by either Western blotting methods.

Key Words: Western blotting • ßbeta;-lactoglobulin • detection methods • adulteration of cheese

Submitted on May 19, 1995
Accepted on October 11, 1995

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