The effect of mono- and disaccharides on structural-mechanical properties of pectin gels

Abstract

For creating the assortment of confectionery products for children, dietetic or functional designation, we examined the influence of mono- and disaccharides - glucose, fructose, saccharose and lactulose, on the structural and mechanical properties of pectin gel, formed on apple puree. It was determined that effective viscosity of pectin gels on glucose or fructose is larger than the viscosity of pectin gel on saccharose. This is explained by the formation of the larger amount of hydrogen bonds between monosaccharides and molecules of pectin. It was found that in the process of storing gels at temperature of 293 K, their strength grows. In this case, in gels on glucose we observed the formation of crystals, connected to the low solubility of glucose. To prevent the growth of crystals and reach necessary structural and mechanical, organoleptic indicators, it is recommended to reduce the amount of glucose in gels by 30 %. It was determined that lactulose increases the amount of free moisture in the pectin gels on saccharose or glucose, which decreases effective viscosity of their structure. In the pectin gels on fructose, on the contrary, the addition of lactulose reduces the total amount of free moisture, which increases effective viscosity of the structure. This is explained by the larger solubility of lactulose compared to saccharose or glucose, and lower than fructose. The thixotropic properties of gel systems with mono- and disaccharides were studied and it was established that under production conditions, mechanical method of conducting thixotropy makes it possible to restore the structure of gel by 85...90 % and conduct the process of molding. We determined the losses of lactulose when storing pectin gels for 7 days, which amount to: 11 % - for gel with saccharose and lactulose, 14,4 % - with fructose and lactulose and 11,8 % - with glucose and lactulose. These data must be included in the formulations of gels with functional properties to provide for the daily need of human organism in prebiotic.