Proteins, functional properties dispersibility

A wide variety of gel formation conditions and a wide variety of measurement parameters have been used to describe these functional properties, Heat-Induced gel formation techniques generally Involve heating protein dispersions at appropriate concentrations In sealed test tubes (7,13.14.15.16.24.25). In sealed cans... 

Q The most detailed studies were reported by Hermansson and Akesson ( , 41) and Hermansson (42) in which the properties of a soy isolate, caseinate, WPC, and model test systems of additive and lean beef or pork were studied. Solubility, swelling, and viscosity (properties reviewed as related to water absorption) were correlated with moisture loss in the raw systems. In cooked systems, the best predictability of meat texture as affected by additive was a statistical model that included the functional properties of swelling and gel strength of protein additive dispersions. 

Much is known of protein functionality in terms of water solubility and dispersibility, the heat coagulation (or heat-setting) property, water... 

Chemical derivatization of proteins to modify functional properties has received limited consideration. Cationic derivatives of food proteins are routinely used (e.g. sodium soy isolates and sodium and calcium caseinates) to improve wettability, dispersibility and handling properties of these proteins (27). 

The limited studies have revealed some of the potential benefits of chemical derivatization for increasing the use of novel proteins by expanding their functional properties. Some of the properties imparted by succinylation may have very specific or unique applications, e.g. as thermo-stable protein dispersions in coffee whiteners, beverages. Derivatization can be used to impart functionality into denatured, insoluble proteins, and thereby increase their value as functional ingredients. 

Casein dissociates from the micelles when milk or a dispersion of casein micelles at pH 5= 6.7 is heated to at least 90°C in the former, the dissociated K-casein is complexed with whey proteins. The functional properties of K-casein-)S-Ig complexes isolated by centrifugation of heated milk have been reported by Singh, Fox and Cuddigan (1993). 

Protein-water interaction plays an important role in the determination and maintenance of the three-dimensional structure of proteins. Water modified the physicochemical properties of proteins. Therefore, protein-water interactions have been the subject of intensive study and have provided significant advances in our understanding of the involvement of water in protein functionality, stability, and dynamics [6]. The thermodynamics of protein-water interaction directly affects dispersibility, wettability, swelling, and solubility of proteins. Surface-active properties of proteins are simply the result of the thermodynamically unfavorable interaction of exposed nonpolar patches of proteins with solvent water. 

The solubility of proteins is an important property that affects and predicts other functional properties. Therefore, the dispersion of protein molecules in continuous phase is essential for expressing their surface activity. However, the effect of solubility on the surface activity of proteins is complicated, and there is no direct correlation between them. In general, a full dispersion of proteins is necessary in order to form a stable protein film at the interface, because insoluble proteins may precipitate at the interface. 

Functional properties of polysaccharides (formation of viscous dispersions and gek) are associated with the mutual interactions of their chains and interactions with other food components (especially water, proteins and Kpids). 

Hydrocolloids are high-molecular-weight hydrophihc biopolymers used as functional ingredients in the food industry for the control of viscosity, gelation, microstructure, texture, flavor, and shelf-hfe. The term hydrocolloid encompasses all the polysaccharides that are extracted from plants, seaweeds, and microbial sources, as well as gums derived from plant exudates, and modified biopolymers made by chemical or enzymatic treatment to be soluble or dispersible in water. The general molecular and functional properties of proteins and polysaccharides are compared in Table 5.1. 

The polysaccharide-protein dispersions have two or more immiscible phases distributed in an emulsion [80]. Parts of these dispersions are mixed to form coacervates and used to accomplish different functional properties [29]. The type of interaction that occurs between proteins and polysaccharides is a veiy important aspect as it affects the rheological properties of the interfaces [80]. 

The ultimate aim of this research work is to understand the stability of colloidal dispersions on the basis of the fundamental surface properties displayed by the same systan. To this end, we show several situations that illustrate the existing relationship between the different phenomena. In particular, we show the differences between the foam stability of two food proteins the complex behavior of foams formed with mixed systems piotein/surfactant, and finally, the stability of foams and emulsions of a model protein. In all the cases, the systems are evalnated over different length scales ranging from structural to functional properties. 

Nanoparticle surface modification is of tremendous importance to prevent nanoparticle aggregation prior to injection, decrease the toxicity, and increase the solubility and the biocompatibility in a living system [20]. Imaging studies in mice clearly show that QD surface coatings alter the disposition and pharmacokinetic properties of the nanoparticles. The key factors in surface modifications include the use of proper solvents and chemicals or biomolecules used for the attachment of the drug, targeting ligands, proteins, peptides, nucleic acids etc. for their site-specific biomedical applications. The functionalized or capped nanoparticles should be preferably dispersible in aqueous media. 

The multilamellar bilayer structures that form spontaneously on adding water to solid- or liquid-phase phospholipids can be dispersed to form vesicular structures called liposomes. These are often employed in studies of bilayer properties and may be combined with membrane proteins to reconstitute functional membrane systems. A valuable technique for studying the properties of proteins inserted into bilayers employs a single bilayer lamella, also termed a black lipid membrane, formed across a small aperture in a thin partition between two aqueous compartments. Because pristine lipid bilayers have very low ion conductivities, the modifications of ion-conducting... 

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