Extent and Depth of Proteolysis

The velocity of the breakdown of proteins and the amounts of resulting compounds produced during ripening are very different for the various kinds of cheese and depend on a range of factors: type and amount of rennet, type of starter bacteria, level of moisture, pH of the cheese, salt%, and storage temperature.

The progression of proteolysis can be monitored by electrophoresis, by HPLC, and by separation of the casein and its breakdown products into groups according to their solubility. In the classic ripening analysis, the extent of proteolysis is defined as the amount of total nitrogen that is soluble at pH 4.4 (12).

The depth of the ripening is defined as the amount of the nitrogen present as amino acids and low molecular nitrogen compounds. The amount of free amino acids can be estimated by nitrogen determination in the filtrate after precipitation with phospho-tungstic acid (13), by a titration with formaldehyde (14), or by other methods (15).

Fig. 3 shows curves for soluble nitrogen production during ripening for blue-veined Danablu cheese, for semihard Danbo cheese with moderate smear ripening, for Cheddar cheese, and for Feta cheese. For the Danbo, curves are also given for amino nitrogen (determined by phospho-tungstic acid or by formol titration) and for NH3 nitrogen [based on data from (5) and (16)].

Proteolysis During Ripining Cheeses

Figure 3 Typical development of soluble nitrogen at pH 4.4 during ripening as percent of total nitrogen for Danablu cheese, for semihard Danbo cheeses and similar Danish cheeses with moderate smear ripening, for Cheddar cheese, and for feta cheese (made by ultrafiltration). For Danbo and similar Danish cheeses, curves are also shown for typical development for amino nitrogen (determined by precipitation with phosphotungstic acid or by formol titration) and for NH3 nitrogen during ripening. (From Refs. 5 and 17.)

Figure 3 Typical development of soluble nitrogen at pH 4.4 during ripening as percent of total nitrogen for Danablu cheese, for semihard Danbo cheeses and similar Danish cheeses with moderate smear ripening, for Cheddar cheese, and for feta cheese (made by ultrafiltration). For Danbo and similar Danish cheeses, curves are also shown for typical development for amino nitrogen (determined by precipitation with phosphotungstic acid or by formol titration) and for NH3 nitrogen during ripening. (From Refs. 5 and 17.)

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