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 pepsin required to inhibit 50% of the binding of the antiserum in this ELISA assay was similar to 81 ng/mL. The limit of detection of the ELISA method was similar to 10 ng/mL, and the coefficient of variation was <10%. This method uses an antiserum capable of dicscriminating porcine pepsin from chymosin and proteinase from Cryphonectria parasitica but not from bovine pepsin. The adsorption of the antiserum against bovine pepsin resulted in a decrease of its cross-reactivity with this milk 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 pepsin in a fresh soft cheese sample.