Whey composition

Rosenberg, M. 2000. Applications for fractionated milk fat in modulating rheological properties of milk and whey composite gels. Aust. J. Dairy Technol. 55, 56-60. 

Recently, Lin et al. [184] used EDBM technology for acidification and decreasing the ionic strength of a fresh cheddar cheese whey. In this study, EDBM process was carried out with or without preliminary decrease of whey mineral salts content by conventional electrodialysis to obtain precipitates with high level of lipids (Figure 21.36). After centrifugation of the treated whey, composition of floes and precipitation yields was determined. 

Casein. Milk contains proteins and essential amino acids lacking in many other foods. Casein is the principal protein in the skimmed milk (nonfat) portion of milk (3—4% of the weight). After it is removed from the Hquid portion of milk, whey remains. Whey can be denatured by heat treatment of 85°C for 15 minutes. Various protein fractions are identified as a-, P-, and y-casein, and 5-lactoglobulin and blood—semm albumin, each having specific characteristics for various uses. Table 21 gives the concentration and composition of milk proteins. 

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). 

Euactioaahty of whey proteia coaceatrates varies with whey type and concentration. Table 5 gives compositional data for whey proteia coaceatrates from differeat sources of whey. These coaceatrates are used ia a limited number of products ice cream and other fro2en desserts, fermented products, coffee whiteners, and whipped toppiags. 

Table 5. Whey Protein Concentrate Compositions from Different Sources ...

Milk. Imitation milks fall into three broad categories filled products based on skim milk, buttermilk, whey, or combinations of these synthetic milks based on soybean products and toned milk based on the combination of soy or groundnut (peanut) protein with animal milk. Few caseinate-based products have been marketed (1,22,23). Milk is the one area where nutrition is of primary concern, especially in the diets of the young. Substitute milks are being made for human and animal markets. In the latter area, the emphasis is for products to serve as milk replacers for calves. The composition of milk and filled-milk products based on skim milk can be found in Table 10. Table 15 gives the composition of a whey /huttermilk-solids-hased calf-milk replacer, which contains carboxymethyl cellulose (CMC) for proper viscosity of the product. 

Recovery, Purity and Amino Acid Composition of CMP. The elution profiles of the CMP powders obtained on size exclusion chromatography 23) are shown in Figure 6. Both CMP isolated from WPC and whey did not contain major... 

Figure 3.2 Evolution of the microstructure of phase-separated biopolymer emulsion system containing pectin and 0.5 vt% heat-denatured (HD) whey protein isolate (WPI) stabilized oil droplets, (a) Composition 1U 3L (one-to-three mass ratio of upper and lower phases). The large circles are the water droplets (W), while the small circles are the oil droplets (O). This system forms a W2/W1-O/W1 emulsion, where O is oil, Wi is HD-WPI-rich and W2 is pectin-rich, (b) Composition 2U 2L. This system forms an 0/Wi/W2 emulsion, where O is oil, Wi is HD-WPI-rich and W2 is pectin-rich, (c) Composition 3U 1L. This system forms an 0/W]/W2 emulsion, where O is oil, Wi is HD-WPI-rich and W2 is pectin-rich. Reproduced from Kim et al. (2006) with permission.

Weinbreck, F., Tromp, R.H., de Kruif, C.G. (2004c). Composition and structure of whey protein/gum arabic coacervates. Biomacromolecules, 5, 1437-1445. 

Isoelectric precipitation results in loss of whey protein as well as undesirable non-protein components. Gillberg (35) has shown that the cystine composition of the isolate is lower than for the meal extract because non-precipitated whey protein has a relatively larger proportion of the total sulfur amino acids. This observation is reinforced by Mattil (36), who showed that the range for amino acid composition was different for several commercial concentrates as compared to commercial isolates. He found methionine to be lower for isolates than for concentrates. 

The caseins are often considered to be rather hydrophobic molecules. However, consideration of the amino acid composition indicates that they are not particularly so in fact, some are more hydrophilic than the whey protein, /3-lactoglobulin (Table 4.2). However, the caseins do have high... 

The sorption behaviour of a number of dairy products is known (Kinsella and Fox, 1986). Generally, whey powders exhibit sigmoidal sorption isotherms, although the characteristics of the isotherm are influenced by the composition and history of the sample. Examples of sorption isotherms for whey protein concentrate (WPC), dialysed WPC and its dialysate (principally lactose) are shown in Figure 7.13. At low aw values, sorption is due mainly to the proteins present. A sharp decrease is observed in the sorption isotherm of lactose at aw values between 0.35 and 0.50 (e.g. Figure 7.13). This sudden decrease in water sorption can be explained by the crystallization of amorphous lactose in the a-form, which contains one mole of water of crystallization per mole. Above aw values of about 0.6, water sorption is principally influenced by small molecular weight components (Figure 7.13). 

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. 

Milk composition expressed in terms of the contents of water (or total solids = 100 - water), fat, protein, lactose, and ash is called gross composition. Protein is often calculated as crude protein by multiplying total N by 6.38, but sometimes it is corrected to true protein 6.38 (TN -NPN) in a few studies, casein and whey protein have been calculated separately. Lactose should be expressed on an anyhydrous basis, but as pointed out previously, this has not always been done. For bovine milk the sum of fat, true protein, anhydrous lactose, and ash would be expected to fall about 0.2-0.3 percentage units short of the total solids contents because of the materials (citrate, NPN, and mis-... 

Raw milk is a unique agricultural commodity. It contains emulsified globular lipids and colloidally dispersed proteins that may be easily modified, concentrated, or separated in relatively pure form from lactose and various salts that are in true solution. With these physical-chemical properties, an array of milk products and dairy-derived functional food ingredients has been developed and manufactured. Some, like cheese, butter, and certain fermented dairy foods, were developed in antiquity. Other dairy foods, like nonfat dry milk, ice cream, casein, and whey derivatives, are relatively recent products of science and technology. This chapter describes and explains the composition of traditional milk products, as well as that of some of the more recently developed or modified milk products designed to be competitive in the modern food industry. 

Most creamery butter is produced by churning sweet cream so that the fat globules coalesce into a soft mass. The federal standard for butter (USDA 1981B) requires not less than 80% milk fat. FAO/WHO standards specify 80% milk fat, as well as no more than 16% water and a maximum of 2.0% nonfat milk solids (FAO 1973). The required fat level is universal. A typical analysis of butter is given in Table 2.3. Whey butter has a similar composition but is derived from the milk fat recovered from cheese whey. 

Table 2.8. Chemical Composition of Selected Commercial Whey-Based Food Ingredients.

Peri, C. and Dunkley, W. L. 1971. Reverse osmosis of cottage cheese whey. I. Influence of the composition of the feed. J. Food Sci. 36, 25-30. 

Buma (1980) reported viscosities for concentrated lactose solutions and concentrated cheese whey in the range of 10 to 40% total solids at temperatures of 20° to 60°C. A 40% lactose solution was considerably more viscous than a corresponding sucrose solution. The viscosity of the whey concentrate was much higher than that of the lactose however, whey viscosity is also influenced by composition and heat treatment. 

Fractionation of milk and titration of the fractions have been of considerable value. Rice and Markley (1924) made an attempt to assign contributions of the various milk components to titratable acidity. One scheme utilizes oxalate to precipitate calcium and rennet to remove the calcium caseinate phosphate micelles (Horst 1947 Ling 1936 Pyne and Ryan 1950). As formulated by Ling, the scheme involves titrations of milk, oxalated milk, rennet whey, and oxalated rennet whey to the phenolphthalein endpoint. From such titrations, Ling calculated that the caseinate contributed about 0.8 mEq of the total titer of 2.2 mEq/100 ml (0.19% lactic acid) in certain milks that he analyzed. These data are consistent with calculations based on the concentrations of phosphate and proteins present (Walstra and Jenness 1984). The casein, serum proteins, colloidal inorganic phosphorus, and dissolved inorganic phosphorus were accounted for by van der Have et al (1979) in their equation relating the titratable acidity of individual cow s milks to the composition. The casein and phosphates account for the major part of the titratable acidity of fresh milk. 

Cultured milk products are manufactured by fermentation of milk or cream by lactic culture microorganisms that produce desirable flavor and rheological properties which are influenced by the composition of the milk or cream, and by the processing conditions used (Richter 1977 Foster et al. 1957 Marth 1974). Cultured buttermilk may be made from skim milk but is sometimes made from milk containing 1.0 to 3.5% milk fat. Some cultured milk products often contain added MSNF and plant gum or modified starch stabilizers to increase viscosity and control whey syneresis. Dextran-producing culture microorganisms are sometimes used to provide needed viscosity to the cultured milk product without the need to add MSNF or stabilizers. Up to 0.1% citric acid or sodium citrate is commonly added as a substrate for... 

---