Changes in a Greek traditional soft cheese, Kopanisti, were followed during ripening. Mature cheese contained > 52% moisture, 22-7% fat and 19-3% protein The as-casein content was hydrolysed faster than the β-casein so that in mature cheese only23 % and 35 % respectively of these proteins remained intact. Soluble N, TCA-soluble N, amino acid N and NH3 were present to the extent of 28.9, 24.6, 14.3 and 6.6% of total N respectively. Leucine, y-aminobutyric acid, valine and alanine were thedominant free amino acids in the mature cheese. Lipolysis was intense and the total free fatty acid content of ripe cheese was ~ 50 g/kg cheese. The rate of liberation of short-chain (C4-C8) fatty acids was higher than that of the longchain. The characteristic rich flavour and peppery taste appeared after 16 d ripening and the best overall cheese quality was produced after 32 d maturation. © 1990, Proprietors of Journal of Dairy Research. All rights reserved.