The diversity of microbiological and biochemical processes occurring while cheeses ripen, interrelations among those processes, as well as their changeability with time make the monitoring of proteolysis and peptidolysis processes difficult. This is why special research projects are performed in many scientific centres aiming at developing a reliable method to monitor the proteolysis process when various types of cheeses ripen. While evaluating the degradation of paracasein during the ripening of Gouda cheese, it was stated that the dynamics of the process of forming low molecular nitrogen compounds was different. During a 6 week period of ripening, the rates of increase in the contents of peptide N, aminoacid N, and aminic N amounted to 280.4; 304.6; and 242.0%, respectively. However, the rates of increase in the contents of soluble peptides in 2% and 12% TCA were definitely lower, and amounted to 167 and 153.8%, respectively. No correlation was found among the content of soluble N, peptides soluble in 2% and 12% TCA, and of the low-molecular nitrogen compounds in cheeses during their ripening. Yet, in the ripe cheeses, the contents of peptide N, aminic N, and of the total content of low-molecular products of the degradation of paracasein were correlated with the content of soluble N at pH 4.6. On the other hand, the content of aminoacid N was not correlated with the content of soluble N, but it was correlated with the amount of soluble peptides in 2% and 12% TCA. Therefore, those alternative methods with 2% and 12% TCA can be useful when comparing the range and depth of proteolysis in ripe Dutch type cheeses. Yet, for the purpose of evaluating the dynamics of proteolysis occurring whilst cheeses ripen, a traditional method for the fractionation of various forms of nitrogen compounds, and their determination with the Kjeldahl method appears to be more suitable. Contrary to Dutch type cheeses, the proteolysis and peptidolysis in the Cheddar cheeses run much slower and evenly owing to a lower water activity and thanks to the constant chemical composition throughout the whole mass. This fact makes it possible to apply alternative methods to monitor the proteolysis process whilst the Cheddar cheese ripens.
Gouda cheese, proteolysis – analytical methods