Microparticle-Enhanced Nephelometric Immunoassay. 2. Measurement of α-Lactalbumin and β-Lactoglobulin

Abstract

A microparticle-enhanced ne helometric immunoassay n w $ was developed for the determination of alactalbumin and &lactoglobulin in bovine milk, whey, and curd from soft cheese (Camembert-type cheese) and pressed cheese (Saint Paulin-type cheese). Diluted milk, whey, and dissolved curd samples were used without pretreatment and mixed with a-lactalbumin-coated or jMactoglobulincoated microspheres and highly diluted anti-a-lactalbumin-specific or anti-& lactoglobulin-specifk antiserum. After a reaction time of 1 h, the light scattered by the clusters of coated microspheres was measured using a nephelometer and compared with calibration curves deve loped with a low heat milk powder, corrected for its heat-sensitive k lactoglobulin content. Recovery (97.2 to 102.2%) and precision (coefficients of variation from 1.4 to 6.1% for milk and whey) studies showed the reliability of this method for the quantitation of whey proteins.