The Liberation of Free Amino Acids in Raw and Pasteurized Milk Cheddar Cheese during Ripening

Abstract

Summary A study was made of the rate of production of free amino acids, amides and amines in American cheddar cheese from the date of manufacture over a ripening period of 180 days at 60° F. Paper partition chromatography was used throughout and the compounds were determined using a rough quantitative procedure. In addition, differences in the character of the amino acids between raw- and pasteurized-milk cheese were noted. The appearance of many free amino acids was very rapid in both raw- and pasturized-milk cheeses. At the end of 2 days at 60° F., 40 per cent of the number of free amino acids that were found in the cheese had appeared. Glutamic acid, leucine-methionine, basic amino acids, valine, and phenylalanine reached high concentrations in the raw milk cheese over the 180-day ripening period, while for the pasteurized milk cheese glutamic acid, basic amino acids, phenylalanine and asparagine increased to high proportions. On the other hand, glutamine, serine, threonine, proline and α-amino-butyric acid were found in low concentrations in raw milk cheese while aspartic acid, alanine, glutamine, threonine and glycine developed in low concentrations in the pasteurized product. Proline, tyramine and α-amino-butyric acid were detected in raw-milk cheese but not in the pasteurized-milk cheese. Asparagine was present in large quantities in pasteurized milk cheese but was not observed in raw milk cheese.