Whey protein isolate isolation

WPC80 whey protein concentrate, 80% protein. WLAC whey lactalbumin. WPI whey protein isolate number reported is mean of three samples. Means with different letters within a column are significantly (p < 0.05) different. 

FIGURE 5.3 Electron micrographs of whey protein isolate (WPI). Scanning electron microscopy of dry WPI powder (A). Transmission electron microscopy of WPI stained with uranyl acetate (B) nonextruded WPI Paste (40% moisture) and (C) extruded texturized WPI (100 °C, 40% moisture) (Onwulata et ai, 2003a). 

TABLE 5.4 Properties of whey protein isolate as function of extrusion temperature (Onwulata et ai, 2003a)... 

FIGURE 5.4 SDS-PAGE of extruded and nonextruded whey protein isolate. (A) With 2-mercaptoethanol (B) without 2-mercaptoethanol. The lanes are temperature and product conditions lane 1,100 °C lane 2, 75 °C lane 3, 50 °C lane 4,35 C lane 5, native WPI lane 6, laboratory whey (Onwulata et al., 2003a). 

FIGURE 5.6 Solubility of texturized dairy protein products extruded at different temperatures, 25 (control), 50, 75, and 100 C Nonfat dried milk (NDM) whey protein concentrate (WPC80), containing 80% protein and whey protein isolate (WPl), containing 95% protein (Onwulata et at, 2003a). 

Onwulata, C. I. (2009). Use of extrusion-texturized whey protein isolates in puffed corn meal. J. Food Proc. Pres. 34(2010), 571-586. 

Onwulata, C. 1., Isobe, S., Tomasula, P. M., and Cooke, P. H. (2006). Properties of whey protein isolates extruded under acidic and alkaline conditions. /. Dairy Sci. 89, 71-81. 

Qi, P. X. and Onwulata, C. 1. (2011). Physical properties, molecular structures and protein quality of texturized whey protein isolate (WPl) Effect of extrusion moisture content. /. Dairy Sci. (Accepted for publication). doi 10.3168/jds.2010-3942. 

Queguiner, C., Dumay, E., Cavalier, C., and Cheftel, J. C. (1989). Reduction of Streptococcus thermophilus in a whey protein isolate by low moisture extrusion cooking without loss of functional properties. Int. ]. Food Sci. Technol. 24, 601-612. 

Bolder, S.G., Hendrickx, H., Sagis, L.M.C., van der Linden, E. (2006). Ca2+-induced cold-set gelation of whey protein isolate fibrils. Applied Rheology, 16, 258- 264. 

All these microcapsules were found to be roughly spherical in shape and of similar size (14-18 pm) (Drusch, 2007). A mixture of chitosan, maltodextrin and whey protein isolate was also found to be also a good wall material for encapsulation of fish oil using an ultrasonic atomizer followed by freeze-drying of the microcapsules (Klaypradit and Huang,... 

Roff, C.F., Foegeding, E.A. (1996). Dicationic-induced gelation of pre-denatured whey protein isolate. Food Hydrocolloids, 10, 193-198. 

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.

In a recent study by Sun et al. (2007) of 20 vol% oil-in-water emulsions stabilized by 2 wt% whey protein isolate (WPI), the influence of addition of incompatible xanthan gum (XG) was investigated at different concentrations. It was demonstrated that polysaccharide addition had no significant effect on the average droplet size (d32). But emulsion microstructure and creaming behaviour indicated that the degree of flocculation was a sensitive function of XG concentration with no XG present, there was no flocculation, for 0.02-0.15 wt% XG, there was a limited... 

In addition to the necessary protection of the contents of the emulsion droplets, effective encapsulation technology requires that the release of the active matter be controlled at a specified rate. Benichou et aL (2004) have demonstrated that a mixture of whey protein isolate (WPI) and xanthan gum can be successfully used for the controlled release of vitamin Bi entrapped within the inner aqueous phase of a multiple emulsion. The release profile, as a function of the pH of the external aqueous phase, is plotted in Figure 7.25. We can observe that the external interface appears more effectively sealed against release of the entrapped vitamin at pH = 2 than at pH = 4 or 7. It was reported that an increase in the protein-to-potysaccharide ratio reduced the release rate at pH = 3.5 (Benichou et aL, 2004). More broadly, the authors suggest that compatible blends of biopolymers (hydrocolloids and proteins) should be considered excellent amphiphilic candidates to serve as release controllers and stability7 enhancers in future formulations of double emulsions. So perhaps mixed compatible biopolymers wall at last allow researchers to... 

Benichou, A., Aserin, A., Lutz, R., Garti, N. (2007). Formation and characterization of amphiphilic conjugates of whey protein isolate (WPI) / xanthan to improve surface activity. Food Hydrocolloids, 21, 379-391. 

Ercelebi, E.A., Ibanoglu, E. (2007). Influence of hydrocolloids on phase separation and emulsion properties of whey protein isolate. Journal of Food Engineering, 80, 454 159. 

Sanchez, C., Schmitt, C., Babak, V., Hardy, J. (1997). Rheology of whey protein isolate-xanthan mixed solutions and gels effect of pH and xanthan concentration. Nahrung, 41, 336-343. 

Sun, C., Gunasekaran, S., Richards, M.P. (2007). Effect of xanthan gum on physicochemical properties of whey protein isolate stabilized oil-in-water emulsions. Food Hydrocolloids, 21, 555-564. 

Rodriguez Patino, J.M., Rodriguez Nino, M.R., Carrera, C., Cejudo, M. (2001b). Whey protein isolate-monoglyceride mixed monolayers at the air-water interface structure, morphology, and interactions. Langmuir, 17, 7545-7553. 

One of the important developments in dairy technology in recent years has been the fractionation of milk into its principal constituents, e.g. lactose, milk fat fractions and milk protein products (caseins, caseinates, whey protein concentrates, whey protein isolates, mainly for use as functional proteins but more recently as nutraceuticals , i.e. proteins for specific physiological and/or nutritional functions, e.g. lactotransferrin, immunoglobulins). 

Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Lactose and lactose derivatives Fresh cheeses and cheese-based products Functional applications, e.g. coffee creamers, meat extenders nutritional applications Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Various fermented milk products, e.g. yoghurt, buttermilk, acidophilus milk, bioyoghurt... 

Ion-exchange chromatography proteins are adsorbed on an ion exchanger, washed free of lactose and salts and then eluted by pH adjustment. The eluate is freed of salts by ultrafiltration and spray-dried to yield whey protein isolate, containing about 95% protein. 

Sternberg, M., Chiang, J. P. and Ebert, N. J. 1976. Cheese whey protein isolated with polyacrylic acid. J. Dairy Sci. 59, 1042-1050. 

A good example of its use applied to a protein associated with food chemistry is that of P-lactoglobulin. Ikeuchi et al. (2001) used ANS as a probe to follow P-lactoglobulin de-naturation under high pressure and its subsequent renaturation on release of pressure (Fig. B3.6.11). The denaturation was shown to be completely reversible at pH 2 but not at neutral pH, explaining why whey protein isolates subjected to high pressures form a gel at pH 7 but not at acid pH. 

JN de Wit, G Klarenbeek, E Hontelez-Backx. Evaluation of functional properties of whey protein concentrate and whey protein isolates. Neth Milk Dairy J 37 37-49, 1983. 

Huang, X.L., Catignani, G.L., and Swaisgood, H.E. 1999. Modification of the rheological properties of whey protein isolates by limited proteolysis. Nahrung 43, 79-85. 

Hunt, J.A. and Dalgleish, D.G. 1994. Effect of pH on the stability and surface composition in emulsions made with whey protein isolate. J. Agric. Food Chem. 42, 2131-2135. 

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