Whey protein matrices

Whey may be substituted for starch by as much as 25% in extruded corn snacks, but the product does not puff as much as com alone, as the water-holding whey protein does not react with the starch matrix (Onwulata et al., 1998). WPCs or isolates can be added along with starch to create expanded snack foods with boosted nutritional content however, without texturization, whey proteins in amounts larger than 15% may interfere with expansion, making the products less crunchy. To counter this effect, whey proteins can be texturized with starch to improve their interaction with other food components in a formulation, principally to increase extmdate expansion. In one successful application, between 25% and 35% of the flour was replaced with whey protein (Onwulata et al., 2001a,b). 

Although the gelation properties of whey proteins are of great importance in many foods (Mulvihill, 1992) and it is possible to form a weak gel in creams by the formation of a continuous network of fat globules, most important milk gels are those involving casein micelles which can be made to form a gel matrix either by isoelectric precipitation (acid-induced gel) or by the action of a proteolytic enzyme (rennet-induced gel). Both gel types... 

Conclusion This preliminary work reveals whey proteins as a convenient material for immobilizing recombinant yeasts. Gel beads were resistant to acidification until pH 2 and pepsin attack, suggesting that they should cross the gastric barrier in humans. Moreover, the presence of the protein matrix seemed to create microconditions that favor the heterologous activity of entrapped yeasts. 

Ultrafiltration may be integrated into the cheesemaking process either for partial milk concentration or full milk concentration (Table 22.1), in which cutting and whey drainage are entirely eliminated and 100% of the whey proteins of milk are retained in the cheese matrix [28,75,76], The reduced volume of the liquid pre-cheese and the absence of whey drainage from the curd when UF pre-cheese is used lead to the reduction of rennet requirement by -80% compared to what is usually needed in conventional manufacture of cheese [25,77],... 

Steady cone-jet electrosprays in liquid insulator baths. ]. Colloid Interface Sci. 272,104—108. Bedie, G. K., Turgeon, S. L., and Makhlouf, J. (2008). Formation of native whey protein isolate—Low methoxyl pectin complexes as a matrix for hydro-soluble food ingredient entrapment in acidic foods. Food Hydrocolloids 22, 836-844. 

After homogenization, the milk proteins readily adsorb to the bare surface of the fat droplets. The proteins are mostly adsorbed on the aqueous side of fat-matrix interface, with hydrophobic parts at the interface. Free casein, casein micelles and whey have different surface activities, so they adsorb differently onto the fat droplets for example, casein adsorbs more than whey. Proteins are very good at stabilizing oil-in-water emulsions against coalescence because they provide a strong, thick membrane around the fat droplet. Interactions between the proteins on the outside of the droplets make it harder for the droplets to come into close contact. This is known as steric stabilization. 

Gbassi, G. K. Vandamme, T. Ennahar, S. Marchioni, E., Microencapsulation of Lactobacillus planta-rum spp in an alginate matrix coated with whey proteins. International Journal of Food Microbiology (2009) 129, 103-105. 

Saufi SM, Fee CJ. Simultaneous aiuon and cation exchange chromatography of whey proteins using a customizable mixed matrix membrane. J. Chromatogr. A 2011 1218 9003-9009. 

Rgure 15.3 shows optical micrographs of capsules, electrosprayed with whey protein concentrate, containing ]8-carotene. It can be seen that the antioxidant is properly encapsulated in the matrix. 

Casein micelles are dispersed in an aqueous phase that contains lactose, small ions and whey proteins. The fat in milk is present in globules (0.2-15 qm diameter) dispersed in the aqueous matrix and stabilized by a membrane of proteins and phospholipids at the oil-water interface. Milk fat is partially crystallized below 40° C. 

---