Whey concentrate

Whey concentration, both of whole whey and ultrafiltration permeate, is practiced successfully, but the solubility of lactose hmits the practical concentration of whey to about 20 percent total sohds, about a 4x concentration fac tor. (Membranes do not tolerate sohds forming on their surface.) Nanofiltration is used to soften water and clean up streams where complete removal of monovalent ions is either unnecessary or undesirable. Because of the ionic character of most NF membranes, they reject polyvalent ions much more readily than monovalent ions. NF is used to treat salt whey, the whey expressed after NaCl is added to curd. Nanofiltration permits the NaCl to permeate while retaining the other whey components, which may then be blended with ordinaiy whey. NF is also used to deacidify whey produced by the addition of HCl to milk in the production of casein. 

During cheese making, the coagulated milk or curd is used to make cheese while the supernatant whey is a waste product rich in salts, proteins, and lactose. Whey concentration and desalting by UF produce a retentate product that can be used as an animal feed supplement or food additive. The MMV process (Maubois et al., French Patent 2,052,121) involves concentrating the milk by UF after centrifugation to remove the cream and before coagulation to improve yields and reduce disposal costs. 

Proteins of egg white denature more rapidly than those of whey protein concentrate (13, 34). However, isolated p-lactoglobulin from the whey concentrate was more susceptible to surface denaturation than egg white ovalbumin. These data suggest that whey contains substances that protect the proteins from surface denaturation and may account for the lower stability of whey protein concentrate foams than those of egg white protein. A balance between the disaggregation effect of select pH values and the tendency toward greater aggregation of proteins at higher heating temperatures were correlated closely with maximum foam stability (13, 15). 

Like the caseins, the whey proteins have been isolated from whey or whey concentrates and purified by differential solubilities, electrophoresis, or chromatography. 

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. 

Coughlin and Nickerson (1975), Vujicic et al. (1977), and Lin and Nickerson (1977) readily hydrolyzed 5 to 40% lactose solutions (w/w) with 1 to 3 N hydrochloric acid or sulfuric acid. Ninety percent of the lactose could be hydrolyzed to the constituent monosaccharides at relatively low temperatures (60°C) and long reaction times (up to 36 hr). The authors were not able to adapt this process to whey concentrate because of degradative side reactions producing high levels of off-flavor and color. Guy and Edmondson (1978) hydrolyzed lactose with 0.1 N hydrochloric acid at short reaction times at 121°C. 

Lactose is recovered from skim milk or whey concentrates or from whey ultrafiltration retentate by crystallization technology (Nickerson 1970). Lactose is also hydrolyzed by chemical and enzymatic processes to form syrups with increased sweetness and improved functionality (Hobman 1984 Zadow 1984). 

Ig, immunoglobulin cw, colostral whey concentrate mw, milk whey concentrate c, colostrum BW, body weight Size not indicated. 

Plock, J., Spiegel, T., and Kessler, H.G. (1997). Reaction kinetics of the thermal denaturation of whey protein in sweet whey concentrated by evaporation. Milchwissenschaft 53, 327-331. 

It has been proven over the years that the effect of fouling can be lessened to some extent for the application of whey concentration by pretreating the feed streams for the ultrafilters. Whey contains many insoluble solids such as casein fines, lipoprotein complex, mineral precipitates, free fats and microorganisms. Clarification of these debris helps reduce fouling potential during ultrafiltration. In addition, it is quite evident that calcium phosphate minerals in whey are not stable and their precipitation in the membrane pores often results in flux decline. Demineralization of whey before ultrafiltration helps maintain high permeate flux considerably [Muir and Banks, 1985]. 

Application of NF in the simultaneous demineralization and concentration of whey, concentration of lactose from the permeate of the UF whey, and the purification of membrane cleaning solutions. 

To date, the fractionation and concentration of whey proteins from cheese whey remain to be one of the more successful industrial applications of UF [22-24]. Due to flux decline during operation, however, Mulvihill and Ennis [38] reported that the practical limit for whey concentration by UF in modem plants is around 24% total solids, with a protein total solids ratio limit of -0.72 1. DF is used to achieve a higher ratio of protein to total solids, -0.80 1, and a total solids content of about 28% [38]. 

There are not many reports about the influence of size and molecular weight on the surface activity of proteins. It was shown [55] that sodium caseinate and proteins from whey concentrate diffuse to the... 

The objectives of this study were to develop fermentative protocol for succinic acid production from cheese whey by A. succinogenes and study the effect of environmental and nutritional factors such as external CO2 supply, pH, inoculum size, and initial whey concentration on succinic acid production. 

In the previous studies, it was reported that initial concentration of carbon source could influence the cell growth and succinic acid production throughout the fermentation [20]. The effect of initial cheese whey concentrations on succinic acid formation was shown in Fig. 1 Maximum succinic acid concentration of 27.9 g/L was obtained at 48 h when the initial concentration of cheese whey was 100 g/L. The succinic acid concentration increased rapidly from 6 to 24 h corresponding to the rapid consumption of lactose during this period. 

Initial cheese whey concentration had a significant effect on the succinic acid yield (P< 0.03) and productivity (P<0.02). After 48 h of fermentation, the highest succinic acid yield of 0.57 was obtained at initial cheese whey concentration of 50 g/L. The succinic acid productivity increased from 0.44 to 0.58 g h L when the initial whey concentration increased from 50 to 100 g/L (Fig. 2). The highest succinic acid productivity of 0.95 g h L was obtained at 24 h with the initial whey concentration of 75 g/L, while the productivity... 

Fig. 1 Effect of initial cheese whey concentration on lactose and succinic acid concentration (pH 6.8, inoculum size of 5%). Solid line and dash line represent the succinic acid concentration and the lactose concentration, respectively. Symbols represent difieient cheese whey concentrations of 50 (empty squares), 75 (empty diamonds), and 100 g/L (empty triangles)...

F - 2 Effect of initial cheese whey concentration on the succinic acid yield and productivity (pH 6.8, inoculum size of 5%, fermentation time of 48 h)... 

Fig. 7 Distribution of end products during the fermentative succinic acid production (initial cheese whey concentration of 50 g/L, pH of 6.8, and inoculum size of 5%)...

The concentration of lactose and lactic acid in the fermentation both varied with the fermentation conditions such as initial cheese whey concentration, pH, cell density, and fermentation time. The lactose concentration in most of the runs is less than 1%, and the lactic acid concentration is about 3%. The fermentation broth obtained from the fermentation tests was mixed, and the lactic acid and lactose concentration was adjusted to 5 and 2% for nanofiltration tests. 

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