Effect of adding free amino acids to cheddar cheese curd on proteolysis, flavour and texture development

Cheddar cheeses were supplemented with cas-amino acids (0-63mmol kg(-1)) during manufacture. Flavour, texture and proteolysis were monitored over a 6-month ripening period. Polyacrylamide gel electrophoresis indicated no differences in proteolysis between experimental and control cheeses. RP-HPLC indicated only minor qualitative differences between the cheeses; however, a higher level of all peptides was evident in cheeses with intermediate levels (21-42mmol kg(-1)) of added amino acids than in the control or in cheeses with the highest level (63mmol kg(-1)) of added amino acids. Concentrations of proline, lysine and NH3 decreased in all cheeses during the first 5 weeks of ripening while only minor increases in other amino acids (particularly in experimental cheeses) were observed. This indicates either a slow production or rapid utilisation of amino acids during this time. Whereas arginine decreased between 3 and 6 months of ripening, the level of histidine, isoleucine and tyrosine remained more or less unchanged and the remaining amino acids increased rapidly, particularly glutamic acid, valine, leucine, phenylalanine, lysine and ammonia. While the experimental cheese with the highest level of added amino acids maintained the highest concentrations throughout ripening, greater release of amino acids (particularly serine, isoleucine; leucine and phenylalanine) was observed in all other experimental cheeses and in the control. Cheeses with intermediate levels of added amino acids developed a flavour and texture superior to either the controls or the cheeses with highest contents of cas-amino acids after a 6-month ripening period. (C) 1997 Published by Elsevier Science Ltd.