DEVELOPMENT OF AN ELISA FOR THE DETECTION OF CAPRINE ALPHA(S1)-CASEININ MILK

A competitive enzyme-linked immunosorbent assay (ELISA) for determinat ion of goat alpha(s1)-casein has been developed using a polyclonal ant ibody generated against alpha(s1)-casein RP-HPLC purified from bulk ca prine milk. The reliability of the ELISA test, optimized using purifie d alpha(s1)-casein as standard analyte, for quantitating alpha(s1)-cas ein was checked either in caseinates (i.e. the isoelectric casein pell et containing all the caprine casein fractions) or in raw caprine milk s. No significant interference by the other caseins was found, and the caseinate concentrations giving consistent determination of the analy te ranged from 250 to 62.5 mu g/ml (w/v). The determination of alpha(s 1)-casein in raw milk can be performed with appropriate dilution of sa mples, and, independently on the alpha(s1)-casein content, the working dilutions ranging from 1:600 to 1:3000 covered the linear range of th e ELISA curve. These results indicate that the developed ELISA may be a useful tool in the routine screening of caprine milk for which the c ontent of alpha(s1)-casein represents an important parameter in modula ting attitude and yield in cheesemaking.