Ripening, cheese

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. 

and in some cheeses five or perhaps six, agents are responsible for these changes  

Coagulant. Most of the coagulant is lost in the whey but some is retained in the curd. Approximately 6% of added chymosin is normally retained in Cheddar and similar varieties, including Dutch types the amount of rennet retained increases as the pH at whey drainage is reduced. As much as 20% of added chymosin is retained in high-moisture, low-pH cheese, e.g. Camembert. Only about 3% of microbial rennet substitutes is retained in the curd and the level retained is independent of pH. 

Porcine pepsin is very sensitive to denaturation at pH 6.7 but becomes more stable as the pH is reduced. 

The coagulant is major contributor to proteolysis in most cheese varieties, notable exceptions being high-cooked varieties, e.g. Emmental and Parmesan, in which the coagulant is extensively or totally denatured during curd manufacture. 

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Kase-pappel,/. wild mallow (Malta sylvestris). -rei, /. cheese factory cheese making, -rei-fung,/. cheese ripening or curing, kilsesauer, a. lactate of. 

Dufosse, L. and de Echanove, C., The last step in the biosynthesis of aryl carotenoids in the cheese ripening bacteria Brevibacterium linens ATCC 9175 (Brevibacterium aurantiacum sp. nov.) involves a cytochrome P450-dependent monooxygenase. Food Res. Int, 38, 967, 2005. 

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... 

In addition to bacterial conversion of L-methionine to cheese aroma compounds, certain cheese-ripening yeasts have been implicated. They include De-baromyces hansenii, Geotrichum candidum, and Yarrowia lipolytica, in addition to Kluyveromyces lactis and Saccharomyces cerevisiae (previously noted). Of these yeasts, Geotrichum candidum was most effective at producing sulfur compounds with the major product being S-methyl thioacetate, with smaller amounts of MT, DMS, DMDS, and DMTS. Kluyveromyces lactis had a similar profile, but produced a much smaller amount of S-methyl thioacetate than did G. candidum. S-Methyl thioacetate is formed by a reaction of MT and acetyl-CoA (Equation 7) ... 

Different authors used RP-HPLC and UV detection to monitor peptide formation during cheese ripening [174-178], providing valuable information about proteolysis. When large hydrophobic peptide need to be separated an lEC represents the best choice [179]. Nevertheless, the identification of these peptides is essential for the complete understanding of the proteolytic process. The peptides eluted from the LC column can be subjected to ESl-MS for molecular weight determination and MS/MS for amino acid sequence determination, which allow rapid peptide identification [172]. HPLC-ESl-MS and MS/MS techniques have been successfully used for peptide mass fingerprint purposes for sequence analysis of purified albumin from Theobroma cacao seeds [180,181]. 

Effect of milk heating on peptide formation during cheese ripening... 

Study on the role of alkaline phosphatase in cheese ripening... 

Proteinase (plasmin) Hydrolysis of peptide bonds, particularly in -casein Reduced storage stability of UHT products cheese ripening... 

Xanthine oxidase Aldehyde+ H20 + 02 - Acid + H202 Pro-oxidant cheese ripening... 

Acid phosphomonoesterase Hydrolysis of phosphoric acid esters Reduce heat stability of milk cheese ripening... 

Rennets. The use of rennets in cheesemaking is the principal application of proteinases in food processing and is second only to amylases among industrial applications of enzymes. The sources of rennets and their role in milk coagulation and cheese ripening are discussed in Chapter 10 and will not be considered here. 

Typically, five steps, or groups of steps, are involved in the conversion of milk to cheese curd coagulation, acidification, syneresis (expulsion of whey), moulding/shaping and salting. These steps, which partly overlap, enable the cheesemaker to control the composition of cheese, which, in turn, has a major influence on cheese ripening and quality. 

The primary starter performs several functions in addition to acid production, especially reduction of the redox potential ( h, from about + 250 mV in milk to —150 mV in cheese), and, most importantly, plays a major, probably essential, role in the biochemistry of cheese ripening. Many strains produce bacteriocins which control the growth of contaminating micro-organisms. 

It is the principal factor affecting the water activity of young cheeses and has a major effect on the growth and survival of bacteria and the activity of enzymes in cheese, and hence affects and controls the biochemistry of cheese ripening. 

Samples G and H of very small batches of experimental Blue cheese ripened for 2 and 3 months, respectively. d Trace. 

The principal approaches used to accelerate cheese ripening are ... 

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

Exploration of this method for controlled release of enzymes to produce flavors of importance in cheese ripening has been pioneered by Kirby and Law (1986), and was recently the subject... 

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