DEVELOPMENT OF AN INHIBITION ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR THE DETECTION OF RESIDUAL PORCINE PEPSIN IN A SOFT CHEESE SAMPLE

An inhibitory ELISA assay was developed for the detection of residual porcine pepsin in a fresh soft cheese. The concentration of porcine pe psin required to inhibit 50% of the binding of the antiserum in this E LISA assay was similar to 81 ng/mL. The limit of detection of the ELIS A method was similar to 10 ng/mL, and the coefficient of variation was <10%. This method uses an antiserum capable of dicscriminating porcin e pepsin from chymosin and proteinase from Cryphonectria parasitica bu t not from bovine pepsin. The adsorption of the antiserum against bovi ne pepsin resulted in a decrease of its cross-reactivity with this mil k coagulant. The selected pH of trisodium citrate solution (pH 6) for the dissociation of curd caseins and for the assay was compatible with ELISA and resulted in acceptable recoveries of residual porcine pepsi n in a fresh soft cheese sample.