Development of a technology of starch modification. Part 1: exposure to ultrasound in a cooling system

Native and modified starches are widely used in food industry to achieve certain viscosity and structure in products. As a result they influence a number of serious parameters of the end product, such as taste, texture, shelf life, and yield of finished products. These functional properties of native starches depend on the type of the molecular structure of polysaccharides of starch, amylose, and amylopectin. Amylose is a linear polymer, which consists of the remains of glucose with α-1-4 glycosidic bond. And amylopectin is very much branched and consists of the same short linear chains as amylose, but also has side chains connected in the points of branching through α-1,6-bonds. The polysaccharides ratio in starch differs and depends on the source of generation of the latter. The average ratio of amylose and amylopectin in wheat starch amounts to 24-28 % for amylose; and 72-76 % for amylopectin. This article is dedicated to studying the influence of ultrasound exposure in a cooling system on the structure and size of starch grains, as well as on the viscosity of starch glues. The obtained results allow to speak of the decrease in the size of starch grains when exposed to durable ultrasound treatment in a cooling system; for starch from soft varieties of wheat after a 15-minute exposure to ultrasound in the range of 1330…392 nm, and for starch from strong varieties of wheat after a 10-minute exposure to ultrasound in the range of 1280…367 nm. When studying the viscosity of the modified starches, the obtained data allow to conclude that the viscosity in the samples produced under the exposure to ultrasound is several times higher than that of the reference samples, what may be explained by a higher emulsifying capacity due to the accumulation of amylose inside the starch grains, and therefore, with a fuller completion of the process of swelling of the grains and their gelatination.