Proteolysis of β-casein in Cheddar Cheese

Abstract

Summaryβ-Casein is highly resistant to proteolysis in Cheddar cheese. A decrease in NaCl concentration reduced its resistance, but even in the absence of salt the amount of proteolysis of β-casein was slight. Proteolysis in Cheddar cheese increased when the moisture levels were raised by adding water. The relative susceptibility of β-casein to proteolysis by rennin was reduced considerably when the concentration of a sodium caseinate solution was raised from 10 to 20%. Sequestering the Ca2+by means of EDTA had no significant effect on proteolysis of β-casein. It would appear that the resistance of β-casein to proteolysis is due to the substrate rather than the enzyme and it is suggested that the reduced relative susceptibility to proteolysis is due to some concentration-dependent physical change in the casein molecule which renders the β-casein inaccessible. The salt concentration would also appear to influence this change.Cheddar-cheese flavour is largely independent of rennet concentration and it is possible to manufacture cheese of satisfactory quality using half-normal rennet levels.

Bitter flavour in dairy products. I. A review of the factors likely to influence its development, mainly in cheese manufacture

“…However, more recently Lawrence and Gilles (1969), in agreement with the results of Stadhouders (1962), observed a decrease in bitterness in Cheddar at salt levels greater than 4.90%, and more retention of the added salt in curd salted at a low acidity than at higher acidity. These observations were confirmed by Phelan et al (1973) and by Golding (1947) for Cheddar cheese prepared under conditions of high moisture content at salt concentrations < 1.6%. These conditions led to extensive proteolysis, causing bitter and putrid flavours.…”

“…In Cheddar cheese,~-casein is highly resistant to proteolysis while usrcasein is extensively degraded; the main reason for this resistance to proteolysis is the formation of B-caseln polymers that are not readily hydrolysed (Phelan et al, 1973;Creamer, 1975).…”

Composition and Sensory Attributes of Retail Cheddar Cheese with Different Fat Contents

“…-casein was degraded to a lesser extent than -casein in all cheeses resulting in the accumulation of -caseins 1, 2 and 3. The relatively higher degradation of -casein compared to -casein, has been extensively reported for Cheddar and other cheese varieties (Creamer, 1975;Mulvihill and Fox, 1980;Wilkinson et al, 1992), and has been attributed to the preferential hydrolysis of -casein at the water activity of cheese (Creamer, 1971) and/or a conformational change in the casein in cheese, owing to the high levels of para-casein level and mineral salts, which renders the -casein less accessible to residual rennet in the cheese (Phelan et al, 1973).…”

Bitter flavour in dairy products. II. A review of bitter peptides from caseins: their formation, isolation and identification, structure masking and inhibition

“…Thus, an extensive hydrolysis will usually result in decreased overail bitterness (Adler-Nissen, 1986a). Out of 3 major fractions of casein, u S 1-'~-, and K-, only uS1-casein is degraded to any extent at the pH, NaCI and calcium lactate levels found in Cheddar cheese (Richardson and Creamer, 1970;Sullivan and Jago, 1972;Pélissier and Ribadeau-Dumas, 1976).~-Casein is more resistant to enzymic degradation because of its high content in proline residues (Phelan et al, 1973;Visser and de Groot-Mostert, 1977), and peptides derived from~-casein are therefore Iikely to be present at much lower levels. Since the C-terminal sequence of~-casein has been shown to possess an extremely bitter taste (Shinoda et al, 1985a), a higher content of hydrophobie amino acids in~-casein would thus make it a greater poten-tial source of bitter peptides than <x scasein.…”