Protein with hydrocolloid

Besides their interesting color application values, betalainic plants are also worthwhile from a nutritional standpoint. Research on this topic has recently been resumed with great scientific vigor in both in vitro and in vivo studies on red beets, amaranth, red-colored Swiss chard, red-violet pitahayas, and especially cactus pears. ° In the future, betalainic color crops will be benchmarked because of their pigment structure and quantity and also because of the individual and synergistic activities of their components such as colorless phenolics, amino compounds, peptides, proteins, and hydrocolloids. 

Pure lipids can be combined with hydrocolloids such as proteins, starches or celluloses and their derivatives, either by incorporating the lipids in the hydrocolloid film-forming solution (emulsion technique) or by depositing the lipid layer onto the surface of the preformed hydrocolloid film to obtain a bilayer (Fennema and Kamper 1986 Krochta and De Mulder Johnston 1997). Multicomponent films have been extensively reviewed by Wu et al. (2002). The addition of nonlipid compounds (hydrocolloids, sugar solids, etc.) as dispersed components in fat materials permits forming fat dispersions (e.g., chocolate. Figure 23.2). 

Badii, F. and Howell, N. K. (2005). Fish gelatin structure, gelling properties and interaction with egg albumen proteins. Food Hydrocolloids 20,630-640. 

Many food formulations contain mixtures of surfactants (emulsifiers) and hydrocolloids. Interaction between the surfactant and polymer molecule plays a major role in the overall interaction between the particles or droplets, as well as the bulk rheology of the whole system. Such interactions are complex and require fundamental studies of their colloidal properties. As discussed later, many food products contain proteins that are used as emulsifiers. Interaction between proteins and hydrocolloids is also very important in determining the interfacial properties and bulk rheology of the system. In addition, the proteins can also interact with the emulsifiers present in the system and this interaction requires particular attention. 

The best multiple emulsions are likely to be prepared by the separation membrane technique, with polymeric amphiphilic, viscosity-enhancing agents, emulsified microemulsions, and proper selection of the amphiphilic blends of biomacromolecules (proteins and hydrocolloids) in each of the interfaces. The main goal remains to obtain submicron multiple emulsion droplets with longterm stability, possibly by replacing the inner emulsion with a microemulsion that is thermodynamically stable (emulsified microemulsions). Better control of the release pattern from the inner phase is stiU far from being achieved. 

Figure 50 Structure of a typical hydrocolloid, emphasizing its rigidity in comparison to the structure of the flexible proteins with the ability to rotate.

The competitive adsorption of different emulsifiers and proteins or hydrocolloids was studied, and it was demonstrated that, with time, the more surface-active surfactant replaces the less active materials. 

There seems to be a sort of analogy here with the arrested phase separation of a protein-stabilized depletion-flocculated emulsion containing a thermodynamically incompatible hydrocolloid like xanthan gum (Moschakis et al., 2005 Dickinson, 2006b). 

Makri, E., Papalamprou, E., Doxastakis, G. (2005). Study of functional properties of seed storage proteins from indigenous European legume crops (lupin, pea, broad bean) in admixture with polysaccharides. Food Hydrocolloids, 19, 583-594. 

The mix is then homogenized at 105 to 210 kg/cm2 (1500 to 3000 lb/in2) to subdivide milk fat globules to sizes ranging from 0.5 to 2 m in diameter. This process is essential to produce a mix with adequate aeration properties so that the final product will contain < 175- m-diameter air cells to contribute a smooth texture. The homogenized mix is cooled and aged to fully hydrate the hydrocolloids, e.g., milk proteins, stabilizers and corn sweetners, and to provide adequate viscosity to the mix. 

In whippable emulsions with a high fat content, the air-water interface of the foam after whipping is dominated by adsorbed deproteinated fat globules. In whippable emulsions with a low fat content other foam stabilizing mechanisms come into play, such as protein-hydrocolloid and protein-emulsifier interactions. The former subject may be studied by... 

Both hydrocolloids and emulsifiers increase the water-binding capacity in the mix (increased % of hydrogen atoms with low T2 and decreased T2 values). A synergistic effect is observed when both ingredients are present. From studies described earlier in this chapter, the effect of hydrocolloids is assumed to be due to simple water binding and increased thickness of protein layers around the fat globules, whereas the effect of emulsifiers may be due to the increased hydration of interfacially bound protein as well as increased hydration of polar groups of emulsifier at the oil-water interface. 

Poncet-Legrand, C., Edelmann, A., Putaux, J.-L., Cartalade, D., Sarni-Manchado, R, Vernhet, A. (2006). Poly(L-proline) interactions with flavan-3-ols units Influence of the molecular structure and the polyphenol/protein ratio. Food Hydrocolloids, 20, 687-697. 

Walkenstrom, P., Panighetti, N., Wrndhab, E., and Hermansson, A. M. 1998. Effects of fluid shear and temperature on whey protein gels, pure or mixed with xanthan. Food Hydrocolloids 12 469-479. 

The hurdles affecting the shelf life of foods also influence other food properties, including texture. The effects of several physical, chemical, and mechanical treatments should be carefully considered in developing new processes and products. It is not enough to describe the composition of a food product and to determine the conditions and types of unit operation necessary to achieve the required quality. How the major food components, such as water, salt, hydrocolloids, starches, lipids, proteins, flavors, and additives, interact with each other and affect the product quality with respect to microstructure, texture, and appearance should be examined. 

Einhorn-Stoll, U., Ulbrich, M., Sever, S., and Kunzek, H. (2005). Formation of milk protein-pectin conjugates with improved emulsifying properties by controlled dry heating. Food Hydrocolloids 19,329-340. 

Neirynck, N., van der Meeren, P., Bayarri Gorbe, S., Dierckx, S., and Dewettinck, K. (2004). Improved emulsion stabilizing properties of whey protein isolate by conjugation with pectins. Food Hydrocolloids 18, 949-957. 

---