Whey proteins, alpha-lactalbumin (alpha-La) and beta-lactoglobulin (beta-Lg), are powerful inducers of allergy in infancy. Since in early infancy milk is the fundamental nutritional source, if breast feeding is not possible or sufficient, an hypoallergenic formula is required. Allergenicity control of hypoallergenic formulas is fundamental to ensure a. safety product. The objective of this work is to develop an immunological method to test residual immunoreactivity of whey hydrolysates during industrial process. Latex agglutination test is rapid, simple and economical, so it is ideal to routine control of whey hydrolysates production. Two latex agglutination test reagents capable of controlling alpha-La or beta-Lg residual immunoreactivity were developed and used. Detection limit of latex reagents was 12 ng/mL for alpha-La and 24 ng/mL for beta-Lg. No cross-reaction between alpha-La and anti-beta-Lg latex was observed. Anti-alpha-La latex reagent cross-reaction with beta-Lg was detected. (c) 2006 Elsevier Inc. All rights reserved.