Extruded crispbreads with grain-blackcurrant distillers’ stillage: the physicochemical and sensory indicators

The relevance of developing functional products based on secondary raw materials is due to trends in increasing the environmental and economic efficiency of the food industry. The possibility of including grain-blackcurrant distillers’ stillage in the composition of extruded crispbreads based on wheat flour as an ingredient with a high content of protein, dietary fibers and phenolic compounds was studied. The aim of the research was to study the effect of the dosage of grain-blackcurrant stillage on the extrusion modes in obtaining extruded crispbreads, the physicochemical and organoleptic characteristics of the products. Mixtures containing up to 20 % grain-blackcurrant stillage were extruded at 155 °C, 17 % moisture content, and constant productivity and screws speed. In terms of process parameters, a reliable decrease in pressure in the pre-matrix zone was found from 4.5 to 3.5 MPa with an increase in the dosage of stillage in the recipe. Adding stillage reduced the hardness of the samples from 9.4 to 4.2–5.5 N and increased the number of microfractures, the product porosity index, from 4,0 to 9.9. Evaluation of the chemical composition showed that the addition of up to 20 % grain-blackcurrant stillage increases the protein content from 12.5 to 17.1 g/100 g, dietary fiber from 5.3 to 11.3 g/100 g, and phenolic compounds from 216 to 558 mg/kg. It was noted that there was no loss of phenolic compounds during the extrusion process; their content in the crispbreads exceeded the calculated values, apparently due to the destruction of high-molecular forms of bound polyphenols during thermomechanical treatment of the mixtures. The tasting panel (n = 22, five-point scale) assigned the sample with 10 % stillage the best ratings for taste (4.4), texture (4.3) and general appearance (4.6); at 20 %, an increase in bitterness was recorded (3.9). The addition of about 10 % grain-blackcurrant stillage ensures the production of crispbreads enriched with protein, dietary fiber and antioxidants, without deterioration of consumer properties, which opens up prospects for their use in healthy diets.