Emulsification proteins

Oilseed proteins are used as food ingredients at concentrations of 1—2% to nearly 100%. At low concentrations, the proteins are added primarily for their functional properties, eg, emulsification, fat absorption, water absorption, texture, dough formation, adhesion, cohesion, elasticity, film formation, and aeration (86) (see Food processing). Because of high protein contents, textured flours and concentrates are used as the principal ingredients of some meat substitutes. 

GA is well recognized as emulsifier used in essential oil and flavor industries. Randall et al., 1998, reported that the AGP complex is the main component responsible for GA ability to stabilize emulsions, by the association of the AGP amphiphilic protein component with the surface of oil droplets, while the hydrophilic carbohydrate fraction is oriented toward the aqueous phase, preventing aggregation of the droplets by electrostatic repulsion. However, only 1-2% of the gum is absorbed into the oil-water interface and participates in the emulsification thus, over 12% of GA content is required to stabilize emulsions with 20%... 

Manoi, K. and Rizvi, S. S. H. (2009). Emulsification mechanisms and characterizations of cold, gel-like emulsions produced from texturized whey protein concentrate. Food Hydro-colloids 23, 1837-1847. 

Soy Protein Concentrates. Both non-functional (low or no solubility) and functional (good solubility, emulsification capacity, and dispersibility) soy protein concentrates (70% protein, dry basis) are commercially available for use in meat products (2-4, 6, j), 15) Normally, a highly functional product with no harsh or bitter flavors is desirable. When used to replace lean meat, non-hydrated concentrate can be used at levels up to 6-7% in finished nonspecific emulsion meats Higher replacement levels or formulas with specific cost/nutrition requirements may use soy protein concentrate with a judicious amount of textured soy protein (6). Excellent yields, cost savings, texture, flavor and nutrient profiles are possible. However, most soy protein concentrates lack sufficient solubility or sufficiently low viscosities to be used in brines for absorption or injection into whole muscle tissue. When legal standards for protein content exist (13), more concentrate must be used to achieve legal minimums. Brine viscosities increase and uniform distribution of brine components throughout the specific whole muscle piece is restricted. Finished product appearance and flavor are easily compromised. Thus, use of soy protein concentrates in whole muscle applications is limited. 

The protein fraction showed low nitrogen solubility and rather low water hydration and oil absorption values relative to those of the proteinates but oil emulsification was quite high. Refined legume fiber had a water hydration capacity of over 20 g/g product. 

Characteristically, legume seeds are rich in protein and contain intermediate to high levels of lysine and threonine which are important in balancing the deficiencies of these essential amino acids in cereal diets. Certain legume proteins, such as soybean, also exhibit strong functional properties, especially water solubility, water and fat binding and emulsification. Thus soybean flours, protein concentrates and isolates have been used widely as nutritional supplements and functional ingredients in foods. 

Pin milling alone improved one functional property, oil emulsification (Table III). The pin-milled flours, protein fractions and proteinates gave oil emulsification values of 70.0-79.0% compared to values of less than 18.0% for starch products. 

The use of albumin microparticles as a drug delivery system was first suggested by Kramer (1974) and several methods for their production were subsequently developed (Gupta and Haung 1989). Most methods involved the application of emulsification methodology and factors involved in this process have been evaluated by a number of authors. However, studies of the in vitro disintegration process of protein microspheres, induced by the presence of protease enzymes in the environment, are limited (El-Samaligy and Rohdewald 1983). 

Beaulieu, L., Savoie, L., Paquin, P., Subirade, M. (2002). Elaboration and characterization of whey protein beads by an emulsification/cold gelation process application for the protection of retinol. Biomacromolecules, 3, 239-248. 

Chu, B.S., Ichikawa, S., Kanafusa, S., Nakajima, M. (2007). Preparation of protein-stabilized p-carotene nanodispersions by emulsification-evaporation method. Journal of the American Oil Chemists Society, 84, 1053-1062. 

Table 7.2 Effect of the presence of an anionic polysaccharide on the measured zeta potential (Q of emulsion droplets stabilized by proteins under experimental conditions corresponding to protein-polysaccharide complexation. In all cases the complexes were formed in the bulk aqueous medium before emulsification.

For reasons that are probably unrelated to their technical performance, these covalent protein-polysaccharide conjugates have not yet been used commercially in food systems. But it seems that it is only a matter of time before the impressive potential of these highly functional ingredients becomes exploited on a commercial scale in various food applications — not just for emulsification, but also for foaming, gelation, waterholding, and encapsulation. 

Dickinson, E. (2008b). Emulsification and emulsion stabilization with protein-polysaccharide complexes. In Williams, P. A., Phillips, G.O. (Eds). Gums and Stabilisers for the Food Industry 14, Cambridge, UK Royal Society of Chemistry, pp. 221-232. 

Interphasic - properties depending on the ability of the protein molecules to form separation and junction films between two inmiscible media, including emulsification, fat uptake, foaming, adsorption, and coacervation. 

Emulsification. Emulsions are dispersed inmiscible droplets within another liquid stabilized by the interphasic compounds (30-49). In dealing with proteins, the disperse liquid is a fat or oil and the stabilizing interphase is a protein product in butter, these phases are reversed. 

Emulsion Capacity is the property of the protein product solution or suspension to emulsify oil. The measurement is of the maximum amount of oil that the mixture will emulsify without losing its emulsion characteristics. The steps involved in this test are 1) Hydration - formation of the aqueous mixture. 2) Oil addition - with agitation the cause of emulsification. 3) Stress - a result of the heat generated during emulsification. 

In products like sausage and meat pies, plant protein additives have been shown to improve binding of the structure and reduce moisture and fat losses. This may be related to the gelling and/or emulsification functions, as well as, water and fat absorption. 

NFDM, which retains casein micelles similar to those in fresh milk, is produced by pasteurization of sklmmllk, vacuum concentration and spray drying under processing conditions that result in either "low heat" or "high heat" product. Low heat NFDM is required for most applications that depend upon a highly soluble protein, as the case for most emulsification applications, since it is manufactured under mild temperature conditions to minimize whey protein denaturation and complexation with casein micelles. 

---