Potatoes starch gels

The rheological behavior of systems containing starch, soybean protein, soybean oil, and water (5 10 10 40) has been studied.1038 The viscosity of the system depends on the origin of the starch. For example, the viscosity of a potato-starch gel markedly decreases upon the addition of protein. In contrast, a cornstarch gel is much more stable and does not show a decrease in viscosity after the addition of protein. The incorporation of proteins into a lipid-starch system shows that proteins are distributed among both components of the system.885... 

FIGURE 17.26 Structure of various closely packed systems, (a) Polyhedral foam or emulsion, (b) Concentrated potato starch gel. (c) Concentrated dispersion of anisometric gel particles ( fluid gel ), (d) Dispersion of fragments of a particle gel (different fragments differ in grayness). Highly schematic. The scales can vary considerably. 

For a younger gel, the modulus and the fracture stress are much smaller, the fracture strain being larger. Especially for a very young potato starch gel, elastic deformability is high, fr being of the order of 3. 

Fish, B.P., Diffusion and thermodynamics of water in potato starch gels, in Fundamental Aspects of Dehydration of Foodstuffs, Society for Industrial Chemistry, London, U.K., 1958, pp. 143-157. 

Other researchers have measured the dittusion coefficient of water in a potato starch gel and reported the results as shown in Fig. 6 [28, 29], The diffusion of internal water is spatially restricted due to the formation of compartments by the starch polymer and the apparent diffusion coefficient is consequently reduced. They estimated the diffusion coefficient within this compartment Dq, the size of the compartment a, and the blocking efficiency of the wall p, using Eq. (20) to obtain the results for the gel with various starch concentrations and storage times. The quantity Dq was found to be smaller than pure water and it increased with increasing storage time. In addition to the polymer that forms the gel wall, the starch molecule that is dissolved in the compartment reduces Dq. In addition, as the starch gel ages, the starch molecules aggregate at the wall. 

On cooking maize starch the viscosity increases when the starch begins to gelatinise. As the temperature rises towards 95°C the viscosity falls. When the paste is cooled the viscosity rapidly increases. The variation of viscosity with temperature is characteristic for each different origin of starch. Potato starch, for example, has a lower gelatinisation temperature than maize starch but has a higher maximum viscosity. When cooled the viscosity of potato starch rises less. Once again amylopectin starches do not show this behaviour as they do not gel. 

Robin, J. P., Mercier, C., Charbormiere, R., and Guilbot, A. (1974). Lintnerized starches. Gel filtration and enzymatic studies of insoluble residues from prolonged acid treatment of potato starch. Cereal Chem. 51, 389 05. 

Ortega-Ojeda, F. E., Larsson, H., Eliasson, A. C. (2005). Gel formation in mixtures of hydrophobically modified potato and high amylopectin potato starch. Carbohydr. Polym., 59, 313-327. 

Fredriksson, H., Bjork, L, Andersson, R., Liljeberg, H., Silverio, J., Eliasson, A. -C., Aman, P. (2000). Studies on a-amylase degradation of retrograded starch gels from waxy maize and high-amylopectin potato. Carbohydrate Polymers, 43, 81-87. 

Properties of 2% Gel of Potato Starch Modified by Ultrasound, X-Rays, y-Rays, and Ultraviolet Radiation5... 

Samec3,5 has conducted comparative studies on the effects of various types of radiation on the properties of the dextrins produced and found notable differences. The origin of the starch seems to be a factor of minor importance, at least upon sonication with 995 kc/s and 120 W. Potato and arrowroot starch gave similar results.309 The action of ultrasound on starch gels produces complex changes.312,313 The mechanism of disintegration has been discussed by Sozaburo.314... 

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