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Aqueous gelatin gels, properties

Bohidar et al. 1998, realized studies of Sol and Gel state properties of aqueous gelatin solutions of concentrations 4%, 6%, 8% and 10% (w/v) were investigated through dielectric relaxation studies done at various temperatures in the range from 20 to 60°C carried out over a frequency range 20Hz-10MHz and no relaxation of any nature was observed. [Pg.101]

Moritaka, H., Nishinari, K., Horiuchi, H., and Watase, M. (1980). Rheological properties of aqueous agarose-gelatin gels./. Text. Studies 11 257-270. [Pg.210]

One of the methods to determine the gd point is the determination of properties such as the storage modulus at a certain firequency as a function of time at a certain temperature or as a function of temperature, when the network formation is apparently instantaneous. The instant or temperature where the storage modulus rises from immeasurably low values is a measure of the gel point - the gel time or the gel temperature - respectively. Another way is to determine the point where the storage and loss moduli cross each other as a function of time or temperature. Te Nijenhuis [11,23,24] made use of the first method to determine the gel point and the maximum gelation temperature of gelatin solutions. Ross-Murphy [9] analysed both methods for the determination of the gel point of aqueous gelatin solutions and concluded that they ate rather inaccurate. [Pg.3]

In the literature, viscoelastic measuinnents before the gel point of gelatin solutions are largely unreported. As far as the author knows, Djabourov et aL [469] were the first to report measuronents of viscoelastic properties of aqueous gelatin solutions before the gel point (down to G = 7 x 10 N/m ) of a 4.7 /o aqueous solution. In about 3 h the system gradually changes from a Newtonian... [Pg.176]

Uses of gelatin are based on its combination of properties reversible gel-to-sol transition of aqueous solution viscosity of warm aqueous solutions abUity to act as a protective coUoid water permeabUity and insolubUity in cold water, but complete solubUity in hot water. It is also nutritious. These properties are utilized in the food, pharmaceutical, and photographic industries. In addition, gelatin forms strong, uniform, clear, moderately flexible coatings which readily sweU and absorb water and are ideal for the manufacture of photographic films and pharmaceutical capsules. [Pg.206]

The property of thermal, reversible gelation is obtained by the addition of water-soluble proteins and protein degradation products to an aqueous solution of poly (vinyl alcohol) 2). Protein products such as albumin, gelatin, glue, a-amino acids, and their condensation products—diketopiperazines—may be used. A typical formulation for the preparation of a thermally reversible gel is ... [Pg.15]

Any formal definition of a gel has been avoided, because its formulation would be difficult on the basis of external properties. By any criterion, a 1 % aqueous solution of agar does form a gel when it is cooled from 95 to 20°, whereas a 1 % solution of sucrose does not but properties may be so continuous between these extremes that any dividing line would be arbitrary. Most of this Chapter is concerned with fairly permanent network structures formed from polymer solutions. As a definition of gels, this description is incomplete. Some cellulose gels, and pastes of gelatinized, starch granules, would be excluded, because they are formed by limited dispersion of solids. In other words, an arbitrary choice will be made to focus on those gels that are dilute with respect to polymer, because the information available about them at the molecular level is more precise than for others. [Pg.270]

Physical gels are formed when water is added to a lyophilic polymer but in insufficient amounts to completely dissolve the individual chains. Various polysaccharides such as pectin, carrageenan, and agarose, and proteins such as gelatin form physical gels in aqueous solution. These types of gels are usually reversible, i.e., they can be formed and disrupted by changing the pH, tanperature, and other solvent properties. [Pg.6]


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See also in sourсe #XX -- [ Pg.211 ]




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