Starch as a functional component of food systems

Starch and other carbohydrates of D-glucose series bind sodium ions but don't bind calcium ones. The affinity of beta-glucosides to sodium ions is much stronger than the affinity of D-glucose and of alpha-glucosides. Some other interrelations between the components of starch-containing food systems are briefly discussed.

[Electron microscopic study of pectin solutions]

Electron microscopic study was carried out of the structure of pectin 0.01% aqueous solutions according to esterification degree at different pH medium. Preparations were prepared by freezing-drying method of solution drop on the formvar film and by the negative contrasting method. Microfibrils of 60-180 A diameter were found. Their aggregation increased with a decrease of the charge of pectin macromolecule (increase of esterification, decrease of pH).

[Rheological properties of a calcium alginate-potato starch hydrolysate-water system]

The rheological properties of liquid solutions and gels of sodium alginate, calcium gluconate and gelling maltodextrin were investigated and compared with the behaviour of pastes and gels of non-degraded potato starch. The dependence of the rheological properties upon the calcium gluconate concentration is extreme. A marked increase in the viscosity of the liquid solutions and maximal values for the hardness and the breaking strength of the gels are obtained at a calcium gluconate/sodium alginate ratio of 0.3. As to breaking strength, elasticity and hardness, the maltodextrin-based gels are many times inferior to the potato starch-based gels. The breaking strength, hardness and elasticity of maltodextrin gels are increased by the addition of sodium alginate and calcium gluconate, which increases their effectiveness when used in foods.

[Artificial macaroni. 2. Biological value of synthetic macaroni]

The authors determined (in vitro) the amino-acid composition and the enzymatic cleavage of protein and starch as well as (in vivo) the biological value of synthetic macaroni produced on the basis of casein, soybean protein and cotton-seed protein. The products based on casein and soybean protein have a great biological value. Cotton-seed protein has a toxic effect. The biological value of synthetic macaroni is mainly determined by the composition of the initial mixture. The processes of production and culinary processing exert no essential effects on protein content, amino-acid composition of the protein and enzymatic cleavage.

[Trypsin interaction with sodium alginate]

The formation of an insoluble product of the interaction of trypsin and sodium alginate at pH 3-9 was studied. The optic density of the system was in an extreme relation to the composition. The insoluble phase was enriched in trypsin. The dispersion phase formed as a result of the electrostatic interaction between alginate macroanion and trypsin macrocation. The interaction brought about the formation of ATn, where n=90-900 (with an accuracy of the term Mw/Mn of alginate). The relation between the composition of the complex and pH was nonmonotonous.