Milk, casein concentrations

Protein-Based Substitutes. Several plant and animal-based proteins have been used in processed meat products to increase yields, reduce reformulation costs, enhance specific functional properties, and decrease fat content. Examples of these protein additives are wheat flour, wheat gluten, soy flour, soy protein concentrate, soy protein isolate, textured soy protein, cottonseed flour, oat flour, com germ meal, nonfat dry milk, caseinates, whey proteins, surimi, blood plasma, and egg proteins. Most of these protein ingredients can be included in cooked sausages with a maximum level allowed up to 3.5% of the formulation, except soy protein isolate and caseinates are restricted to 2% (44). 

Studies into the effect of frequency of milking on milk quality compared once-daily and twice-daily milking and showed that milk yield was significantly reduced and milk fat and protein concentrations were increased, with once-daily milking compared with twice-daily. Furthermore, casein concentrations in the milks were similar, but once-daily milk had higher whey protein content (O Brien et al., 2002). 

The casein concentration in milk is affected by heredity, feed, season, state of lactation, and milk storage. The first four factors are dealt... 

Keenan, 1975 Neville et al., 1981 Watters, 1984 Virk et al., 1985), the presumption is that the formation of casein micelles is orchestrated with the transport of ions, the phosphorylation and glycosy-lation of the caseins, and lactose synthesis, such that the intravesicular ionic environment and casein concentration change continuously during the 20 min or so required for micelle assembly. Patton and Jensen (1975) observed, in electron micrographs, the same density of micellar particles in the alveolus as in mature vesicles, suggesting that, by this stage, the vesicular concentrations are virtually identical to those in the aqueous phase of milk. 

The most thorough study of the formation of artificial casein micelles is that of Schmidt and co-workers (1977 1979 Schmidt and Koops, 1977 Schmidt and Both, 1982 Schmidt and Poll, 1989), who not only studied the properties of the casein aggregates but also attempted to relate them to the solution conditions under which they were formed. In the precipitation of calcium phosphate from solution, the means by which solutions are mixed together is of crucial importance Schmidt et al. (1977) described a method in which four solutions were pumped simultaneously into a reaction vessel while keeping the pH constant. As a result of careful, slow mixing, the reproducibility of the size distributions of particles, measured by electron microscopy on freeze-fractured and freeze-etched specimens, was very good. In the first series of experiments, the objective was to produce milk like concentrations of the most important ions while... 

Korolczuk, J. 1982. Viscosity and hydration of neutral and acidic milk protein concentrates and caseins. NZ J. Dairy Sci. Technol. 17, 135-140. 

MUk coagulation depends on a number of factors, such as the kinetics of the enzyme reaction, the concentration, and the state of the proteins, especially casein, the balance of minerals, especially calcium, and pH [101]. Most of these factors are directly influenced by UF or MF processing. Caron et al. [101] compared the rennet coagulation properties of nfilk enriched with a regular ultrafiltered retentate powder (RUF) to milk enriched with a diafiltered MF (DMF) retentate powder. RUF was prepared by concentrating skim milk to concentration factor of 5 by UF, while DMF was prepared from skim nfilk concentrated... 

The alteration of mineral and casein equilibria is reflected in changes to the physical properties of milk. The addition of citrate and different types of phosphates (ortho-, pyro-, or hexameta) to milk protein concentrate solutions, which alters the distribution of calcium and inorganic phosphate between the colloidal and serum phases of milk, affects its turbidity and buffering capacity (Mizuno and Lucey, 2005). The turbidity is affected because dissolution of colloidal calcium phosphate is accompanied by release of caseins into the serum. 

Superior foaming properties of milk have been obtained by addition of calcium complexing agents. Kelly and Burgess (1978) demonstrated that addition of sodium hexametaphosphate to milk protein concentrate solutions prepared by ultrafiltration improved foam volume and stability on whipping. The addition of EDTA to milk, which causes dissociation of the casein micelle, improved the foaming properties of milk (Ward et al., 1997). 

Anema, S.G. 2008a. Effect of milk solids concentration on whey protein denaturation, particle size changes and solubilization of casein in high-pressure-treated skim milk. International Dairy Journal 18 228-235. 

Alkali albumtnaies—protcins of Hoppe Seyler—ore formed when an albuminoid is dissolved in concentrated solutions of potassium and sodium hydrates it is very probable that they are identical with serum and milk-casein. 

Functional properties of some enzymatically modified and EPM-treated products of milk proteins [136] were determined as follows. An enzymatically prehydrolyzed commercial milk protein concentrate (SR) without further hydrolysis, and casein hydrolyzed by alcalase, a-chymotrypsin, and papain, respectively, were used as substrates in the EPM reaction. The concentration of the hydrolysates was 20% w/ v in the EPM reactions. A methionine methyl ester hydrochloride/ substrate ratio of 1 5 was used for incorporating this amino acid. After incubation, the products with methionine incorporation were simultaneously dialyzed for 2 days through a cellophane membrane against distilled water. The nondialyzable fractions and the EPM products without amino acid enrichment were freeze-dried. Covalent methionine incorporation in the EPM products with amino acid enrichment was verified by exopeptidase hydrolysis of the protein chains. The functional properties of the different EPM products are summarized in Table 1. An important functional property of proteins and/or peptide mixtures is their emulsifying behavior. This is highly influenced by the molecular structure, the position and ratio of hydrophobic-hydrophilic amino acids. Emulsion activity was found to be low (34.0) for casein, and the values determined for enzyme hydrolyzed and modified products were in general even lower. The papain hydrolysate, sample H3, showed here a different behavior as well this was the one of the sample series that had the highest EAI value (43.0). The emulsion stability of the enzymatically modified products displayed tendencies quite opposite to the values of emul-... 

Cheese contains a high concentration of essential nutrients relative to its energy content. Its precise nutrient content is influenced by the type of milk used (species, stage of lactation, whole fat, lowfat, skim), method of manufacture, and to a lesser extent the degree of ripening. As outlined in detail elsewhere in this review, water-insoluble nutrients of milk (casein, colloidal minerals, fat, and fat-soluble vitamins) are retained in the cheese curd whereas the water-soluble constituents (whey proteins, lactose, water-soluble vitamins, and minerals) partition into the whey. However, loss of water-soluble B vitamins in whey may be compensated to a certain extent by microbial synthesis during ripening (Renner, 1987). 

Milk is one of the oldest constituent of human nutrition. Raw milk is, however, frequently unsafe for human consumption. The basic function of the dairy and milk industry is the transformation of this perishable product into a hygienic one, for widespread consumption. However, the evolution of the milk industry requires new markets for milk and its derivatives. We should now consider milk as a source of ingredients to fulfil the needs of food, pharmaceutical and even cosmetic industries. To take advantage of the rich potential of milk, we must first optimize the techniques for isolation of its constituents. Secondly, we must characterize these constituents in an attempt to evaluate their potential for utilization. The physical chemistry of milk constituents is our main interest, and, as a first step. We have concentrated our efforts on milk caseins. 

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