The influence of moisture content on extrusion modes and physicochemical parameters of extrudates with the addition of chokeberry pomace hydrolysate

Abstract

The influence of the moisture content during the extrusion of a mixture of rice with chokeberry pomace hydrolysate on the process parameters, physico-chemical, structural, textural and technological properties of the extrudates was studied. The relevance of the study is due to the need to increase the sustainability of technological processing of fruit and berry raw materials and increase the efficiency of using by-products of food industry. Hydrolysate of chokeberry pomace was obtained using a complex of enzymes, including pectinase, cellulase, protease and lipase. The hydrolyzate was dried, added to rice in an amount of 5 % and extruded at various moisture content in the range of 15…24 %. An increase in moisture content during extrusion reduced the process temperature from 165 to 148 ℃, the pressure from 5.0 to 2.0 MPa and the torgue from 88 to 48 %. A decrease in moisture reduced the intensity of the impact of the treated mixtures on biopolymers. The specific mechanical energy decreased from 0.17 to 0.09 kW hour/kg. The trends in changes in thermomechanical treatment modes, determined by moisture as a factor reducing friction, were identical for the control and experimental mixtures without significant differences. With an increase in moisture content during extrusion, the hardness of samples containing berry pomace hydrolysate increased from 11.1 to 43.5 N, bulk density from 97.0 to 278.8 g/dm3, and the sectional expansion index decreased from 8.5 to 3.0. The dynamic viscosity of suspensions of ground extrudates under hydration conditions simulating instant steeping in domestic conditions increased significantly from 2.0 to 3.4…4.4 Pa s with an increase in moisture content during extrusion. Extrusion increased the content of phenolic substances in samples with chokeberry pomace hydrolysate. The maximum value of 631.5 mg/dm3 corresponded to 15 % moisture content.