Cheddar ripening

Although not well understood, demethiolation has been noted in some fungi.38 Moreover, evidence for a required enzyme activity was obtained for lactococci (used in cheddar cheese production)40 and a relatively high level of demethiolase activity was present in Kluyveromyces lactis, a cheese-ripening yeast (see below).41... 

The production of sulphur compounds is believed to be very important in the development of Cheddar cheese flavour. Residual sulphydryl oxidase activity may play a role in initially reoxidizing sulphydryl groups exposed upon heating cheesemilk the sulphydryl groups thus protected may be reformed during the ripening process. 

While rennet-coagulated cheese curd may be consumed immediately after manufacture (and a little is), it is rather flavourless and rubbery. Consequently, rennet-coagulated cheeses are ripened (matured) for a period ranging from about 3 weeks for Mozzarella to more than 2 years for Parmesan and extra-mature Cheddar. During this period, a very complex series of biological, biochemical and chemical reactions occur through which the characteristic flavour compounds are produced and the texture altered. 

Proteolysis has not yet been fully characterized in any cheese variety but considerable progress has been made for Cheddar and, as far as is known, generally similar results apply to other low-cook, internal bacterially ripened cheeses (e.g. Dutch types). Proteolysis in Cheddar will be summarized as an example of these types of cheese. 

Figure 10.19 Urea-polyacrylamide gel electrophoretograms of Cheddar cheese after ripening for 0, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18 or 20weeks (lanes 1-14) C, sodium caseinate. (Supplied...

Elevated ripening temperatures, especially for Cheddar which is now usually ripened at 6-8°C most other varieties are ripened at a higher temperature, e.g. around 14°C for Dutch types or 20-22°C for Swiss types and Parmesan, and hence there is little or no scope for increasing the ripening temperature. 

Wilkinson, M.G. (1992) Studies on the Acceleration of Cheddar Cheese Ripening, Ph.D. Thesis, National University of Ireland, Cork. 

A Cheddar-type cheese retains 48% of total solids of milk, 96% casein, 4% soluble proteins, 94% fat, 6% lactose, 6% H20, 62% calcium, 94% vitamin A, 15% thiamin, 26% riboflavin, and 6% vitamin C (National Dairy Council 1979). The lactose content varies in freshly prepared cheeses and decreases rapidly during ripening, completely disappearing in four to six weeks. The enzymes and ripening agents responsible for the rate and extent of fat and protein breakdown are fully discussed in Chapter 12, and vitamin variation is discussed in Chapter 7. 

Majeed, G. H. 1984. Survival of porcine pepsin during Cheddar cheesemaking and its effect on casein during cheese ripening. Ph.D. Thesis. Utah State University, Logan. 

Rao, K. S. N., Krishna, N., Nand, K., Srikanta, S., Krishna-Swamy, M. A., and Murthy, V. S. 1979. Changes during manufacture and ripening of Cheddar cheese prepared with fungal rennet substitute of Rhizopus oligosporus. Nahrung 23, 621-626. 

Rennet is inactivated at the high cooking temperatures used in Swiss and Mozzarella but is still active in Cheddar curd cooked to 39 °C (Matheson 1981). Residual rennet activity has implications for the subsequent ripening of the cheese. 

Umemoto, Y. and Sato, Y. 1975. Relation of Cheddar cheese ripening to bacterial lipoly-sis. Agr. Biol Chem. 39, 2115-2122. 

During cheese ripening, proteases associated with starter culture organisms are released into cheese after cell lysis (Law et al. 1974). The proteolytic activity associated with lysed lactic streptococci is necessary for proper flavor development in Cheddar and other cheese varieties. The role of streptococcal proteases and peptidases appears to be production of flavor compound precursors such as methionine and other amino acids, rather than direct production of flavor compounds (Law et al. 1976A). Additional discussion of cheese ripening is presented in Chapter 12. 

Micrococci comprise approximately 78% of the nonlactic bacteria in raw milk Cheddar cheese (Alford and Frazier 1950). The proteolytic system of Micrococcus freudenreichii functions optimally at 30 °C and at a pH near neutrality (Baribo and Foster 1952). An analysis of pro-teinases present in 1-year-old Cheddar cheese indicates that micrococci may contribute to proteolytic activity (Marth 1963). Proteolytic micrococci also contribute to the ripening of surface-ripened cheeses such as brick and Camembert (Lenoir 1963 Langhus et al. 1945). Micrococcal proteases probably contribute to development of ripened cheese flavor when ripening temperatures are above 10°C (Moreno and Kosikowski 1973). This effect results from degradation of /3-casein. 

Law, B. A., Sharpe, M. E. and Reiter, B. 1974. The release of intracellular dipeptidase from starter streptococci during Cheddar cheese ripening. J. Dairy Res. 41, 137-146. 

Marth, E. H. 1963. Microbiological and chemical aspects of Cheddar cheese ripening. J. Dairy Sci. 46, 869-890. 

Park, H. S., Marth, E. H., Goepfert, J. M. and Olson, N, F. 1970. The fate of Salmonella typhimurium in the manufacture and ripening of low-acid Cheddar cheese. J. Milk Food Technol. 33, 280-284. 

Olson, N, F. 1975. Mechanized and continuous cheese making processes for cheddar and other ripened cheese. J. Dairy Sci. 58, 1015-1021. 

Amantea, G. F., Skura, B. J., and Nakai, S. (1986). Culture effect on ripening characteristics and rheological behavior of Cheddar cheese. J. Food Sci. 51,912-918. 

Chen, M., Irudayaraj, J., and McMahon, D. J. (1998). Examination of full fat and reduced fat Cheddar cheese during ripening by Fourier transform infrared spectroscopy. J. Dairy Sci. 81, 2791-2797. 

Chin, H. W. and Rosenberg, M. (1998). Monitoring proteolysis during Cheddar cheese ripening using two-dimensional gel electrophoresis. J. Food Sci. 63,423-428. 

---