Cheese moisture content

Wehling and Pieree (59) determined the Cheddar cheese moisture content, with a ripeness interval between 3 and 6 months. They concluded that reflectance measurements from grated samples allowed reliable determination of the constituents. 

Proposed IDE standards for caseiaate are hsted ia Table 4. la most cases the sodium salt is preferred for emulsificatioa the calcium salt is preferred for imitation cheese. Caseia and caseiaates must be stored carefliUy and evaluated for flavor before use ia products. Improperly manufactured or stored caseia—caseiaate has a very stroag, musty off-flavor. Excessive fat coateat, high lactose and moisture contents, and high storage temperatures contribute to undesirable flavor development. 

Typically, sorption isotherms are constructed for a single food ingredient or food system. An alternative approach is to plot the moisture content versus water activity (or relative vapor pressure) values for a variety of as is food ingredients and food systems. The result is a composite food isotherm (Figure 17). The composite isotherm fits the typical shape observed for a sorption isotherm for an individual food system, with a few products falling above or below the isotherm curve (chewing gum, honey, raisins, bread, and colby and cheddar cheeses). Slade and Levine (1991) were the first to construct such a plot using moisture content and aw values from van den... 

Syneresis. Renneted milk gels are quite stable if undisturbed but synerese (contract), following first-order kinetics, when cut or broken. By controlling the extent of syneresis, the cheesemaker can control the moisture content of cheese curd and hence the rate and extent of ripening and the stability of the cheese - the higher the moisture content, the faster the cheese will ripen... 

Salting promotes syneresis and hence reduces the moisture content of cheese about 2 kg of water are lost for each kilogram of salt absorbed. 

The most significant and distinguishing characteristic is used for the classification. Typical analyses of two or three representative cheeses that are classified on the basis of moisture content and manner of ripening are presented in Table 2.5. Federal standards of identity are given in Table 2.6 for some selected cheeses. For an in-depth study of cheeses, Kosikowski s (1978A) book, Cheese and Fermented Milk Foods, should be consulted. 

Many milk constituents affect the manufacturing and various characteristics of cheese, but milk fat and casein are of primary importance since they constitute most of the solids in cheese (e.g., 91% of the solids in Cheddar cheese). These two constituents, plus water, influence the yield of cheese from milk and the gross composition of cheese (Van Slyke and Price 1952). Formulas used to predict the cheese yield from milk include the concentration factors of casein and fat in milk, a minor correction factor for other milk constituents, and the added salt and moisture content of cheese (Van Slyke and Price 1952 Lelievre et al. 1983 Banks et al. 1984). 

The casein micelles become surrounded by whey proteins and cannot interact with one another, thus reducing whey syneresis. This results in a soft curd that retains more moisture. The yield of cheese is increased due to the incorporation of whey proteins and the higher moisture content. Overheated milk requires longer rennet coagulation times. If milk is heated for 30 min at 75° C, it will not clot at all (Ustu-nol and Brown 1985). 

Excessive or insufficient acid development during manufacture can produce variability in the moisture content of cheese and defects in flavor, body, texture, color, and finish (Van Slyke and Price 1952). The rate of lactose fermentation varies with the type of cheese, but the conversion to lactic acid is virtually complete during the first weeks of aging (Van Slyke and Price 1952 Turner and Thomas 1980). Very small amounts of lactose and galactose may be found in cheese months after manufacture. (Huffman and Kristoffersen 1984 Turner and Thomas 1980 Harvey et al. 1981 Thomas and Pearce 1981). Turner and Thomas (1980) showed that the fermentation of residual lactose in Cheddar cheese is affected by the storage temperature, the salt level in the cheese and the salt tolerance of the starter used. 

Fat is a major component in most cheese types, but its level and importance differ markedly with variety. Inter- and intra-variety differences in fat content are affected by a number of factors, including milk composition (particularly ratio of protein to fat), and the cheesemaking process (recipe, manufacturing procedure and technology), which control the levels of milk fat and moisture retained in the cheese curd and the moisture content of the cheese. The ratio of protein-to-fat in the cheese milk is probably the principal factor influencing fat content, as it controls the relative proportions of two of the three major compositional components in cheese, namely protein and fat the third major component is moisture. Owing to the inverse relationship between the percentage of moisture and fat in cheese, as discussed in Section... 

Figure 11.5. Effect of fat content on the percentage moisture in Cheddar cheese (O) and the weight of Cheddar cheese moisture obtained from 100 kg cheesemilk (A) (drawn from data of Fenelon and Guinee, 1999 Guinee et al., 2000a).

Cunha et al. [79] noted an increase in the titratable acidity with increasing concentration factor (from 1.2 to 1.8) in the UF of semi-skimmed milk (1.33% fat) using 10 kDa MWCO Romicon polysulfone hollow fiber membrane at 50°C. They explained that this result is mostly due to the protein concentration, which increased the apparent acidity of the retentates and promoted an increase in its buffering capacity. When the UF retentates were made into reduced-fat Minas Frescal cheese, they noted a decrease in yield with increasing concentration factor, due to the decrease in moisture content. 

Intermediate Moisture Foods (IMF s) are characterised by a moisture content of about 15 to 50% and by an aw between 0.60 and 0.85. Traditional IMF s, such as jams, fruit cakes and some ripened cheese are stable at ambient temperatures for various shelf periods (Table 3.59). Water content of IMF s may be lowered to a level which prevents microbial spoilage by the addition of humectants, pH adjustments and antimicrobial agents. Newer IMF s, such as designed for space rations, clinical nutrition and pet foods, can be prepared by adjusting the formulation of the product so that its aw is below 0.86 by use of the following techniques [11 ] ... 

Type of agent High fat content (butter, fats, cheese, meat, bacon, and shell eggs, etc.) Low fat, high moisture content (fruit, vegetables, sugar, salt, etc.) Low fat, low moisture content (cereal, tea, coffee, flour, bread, rice, etc.)... 

Temperature also has a similar effect on the dielectric properties of cheese. The effect of temperature, however, depends on the moisture content of the cheese being processed. Medium-moisture content cheese exhibits a decrease in e for temperatures between 5°C and 55°C. Further increase in processing temperature results in an increase in e. The increase in e value reversed again at 65°C. The decrease in s value between 65°C and 85°C is common for both medium- and low-moisture cheese. The dielectric property changes at higher temperatures are similar to that of soy protein. Higher processing temperatures result in protein denaturation. 

The loss factor (s") for higher- and medium-moisture content cheese increases gradually with temperature (5°C-85°C). The trend is opposite for low-moisture cheese. The increase in s" for high- and medium-moisture cheese could be attributed to ionic conduction. It was reported that the effect of temperature was more pronounced at lower frequencies than at higher frequencies (above 1 GHz) (Nelson and Bartley, 2000). Models were also developed to predict the effects of moisture and salt content. These models can provide the effects of frequency, temperature, and compositions on microwave processing of cheese. 

High-pressure treatment of milk increased yield of cheese due to increased WHC as well as to denaturation of whey proteins and their association with casein. Drake et al. (1997) attributed the increased yield and higher moisture content of cheese made from high-pressure treated milk to the fact that casein molecules and fat globules might not aggregate closely and hence allow moisture to be trapped or held in cheese. Pandey and Ramaswamy (1998) reported that reduced hardness of Cheddar... 

Pandey, P.K. and Ramaswamy, H.S. 1998. Effect of high pressure of milk on textural properties, moisture content and yield of Cheddar cheese. In Book of abstracts of IFTAnnual Meeting, Atlanta, GA, pp. 173-174. 

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