Curd formation

Within each group, individual cheeses are characterized by aroma. A small selection of the more important cheese varieties is listed in Table 10.30. Cheese manufacturing essentially consists of curd formation and ripening (Fig. 10.26). 

New methods of cheese making aim at including the whey proteins in the curd, instead of removing them with the whey. Apart from giving higher yields (12-18%), these processes help to economize on waste water costs or elaborate whey treatments (cf. 10.2.10). 

The use of ultrafiltration steps as compared with conventional cheese making is shown in Fig. 10.26. Alternatively, conventionally produced whey can be concentrated by ultrafiltration and then added to the curd or milk can be soured with starter culture and/or rennet 

Type of cheese Starter cultures Other species 

Parmigiano-Reggiano Streptococcus thermophilus Lactobacillus helveticus L. bidgaricus  

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Whey is the fluid obtained by separatiag the coagulum from cream and/or skim milk, and is a by-product of either caseia or cheese manufacture. The composition of whey is determined by the method of curd formation, curd handling practices, and methods of handling whey as it is separated from the curd. Dried acid whey contains ca 12.5 wt % proteia (total nitrogea x6.38), 11.0 wt % ash, and 59 wt % lactose, whereas sweet whey contains 13.5 wt % proteia, 1.2 wt % fat, 8.4 wt % ash and 74 wt % lactose. The composition varies with the type of acid used (7). 

The high casein content of cow s milk is responsible for the formation of a large, firm curd which may be difficult for some infants to digest compared with the finer, soft curd formed from human milk. Consequently, cow s milk often is modified to conform more closely to the nutrient and physical requirements of infants (Fomon 1974). When cow s milk is heated, homogenized, or acidified to produce softer curd formation, the protein is used by infants as efficiently as that of human milk, which contains less casein than cow s milk (Fomon 1974). 

Hori, T. 1985. Objective measurement of the process of curd formation during rennet treatment of milks by the hot wire method. J. Food Sci. 50, 911-917. 

Raw milk is standardized to the proper fat and total milk solids content to produce a final product with a minimum of 50% fat on a solids basis and <39% moisture (CFR 1982 Packard 1975). Cheese is made from pasteurized or raw milk, but raw milk cheese must be aged a minimum of 60 days at >1.7°C (CFR, 1982). Minimum temperature and time combinations are normally used for pasteurization of milk for cheese manufacture in order not to interfere with casein micelle coagulation and curd formation. Milk is sometimes heated only to subpasteurization temperatures to dispel dissolved gases, reduce bacterial populations, and kill certain pathogens, thus resulting in a cheese product with improved flavor (Babel 1976). 

Such applications appear to be more attractive for the use of bioreactors than traditional uses of endopeptidases for chillproofing beer, juice clarification, and curd formation in cheesemaking which currently use well established soluble enzyme processes. In the case of curd formation, hydrolysis of micellar k-casein by immobilized chymosin is questionable (56). 

Mahfuz, A.A. C. Tsukamoto S. Kudou T. Ono. Changes of astringent sensation of soy milk during tofu curd formation./. Agric. Food Chem. 2004, 52, 7070-7074. 

Dairy Milk curd formation for cheese making rennet fungal calf stomach 5... 

Milk contains 3.3% total protein. There are two major categories of milk protein that are broadly defined by their chemical composition and physical properties. The casein family contains phosphorus and will coagulate or precipitate at pH 4.6. The serum [whey] proteins do not contain phosphorus, and these proteins remain in solution in milk at pH 4.6. The principle of coagulation, or curd formation, at reduced pH is the basis for cheese curd formation. In cow s milk, approximately 82% of milk protein is casein and the remaining 18% is serum, or whey protein. 

Curd formation (using acids, rennet extract or a combination of both). 

The equipment used includes discontinuously operated cheesemakers (vats or tanks with stirring and cutting devices) and coagulators for continuous curd formation with subsequent fully automatic whey separation and molding. 

Dairy products. Aid in curd formation for making cottage cheese, additive for evaptnaled... 

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