Ripening of Ossau-Iraty cheese: determination of free amino acids by RP-HPLC and of total free amino acids by the TNBS method.

摘要

The free amino acids and sulphosalicylic acid-soluble N fraction in the French ewe milk cheese, Ossau-Iraty, were determined to evaluate the degree of proteolysis during ripening of the cheese. Reverse phase-HPLC was used to assess the free amino acids, and the trinitro-benzene sulfonic acid method was used to assess the sulphosalicylic acid-soluble N fraction. The total free amino acids content ranged from 200 mg/100 g DM on the first day of ripening to 2200 mg/100 g DM after 120 days of ripening.The major amino acids were glutamic acid, asparagine, glutamine, valine, leucine, phenylalanine and lysine, which accounted for between 50% (on day 1) and 70% (on day 120) of the total free amino acids. Correlations between the main free amino acids andripening time were high. Regression of the sulphosalicylic acid-soluble N fraction on total free amino acids yielded a correlation coefficient of 0.985.