Microplate assay of free amino acids in Swiss cheeses

Abstract

A microplate assay to measure the total amount of free amino acids in cheese was developed using a Cd-ninhydrin reagent. The method allows rapid determination of amino acids using small sample volumes which renders routine analyses very simple. Comparison of the results with those obtained by HPLC or IEC analyses have a correlation coefficient ranging between 0.979 and 0.999. Values obtained with the microplate assay were systematically 10 to 25% lower than the HPLC or IEC-values; no satisfactory explanation for this underestimation was found. The effect of milk pasteurization on cheese proteolysis was also studied. © 1996 Academic Press Limited.