EVALUATION OF PROCESSES TO ENHANCE GRAIN AND MEAT COPRODUCTS

Abstract

Blends of soybean meal (SBM) and pork red blood cells (RBC) or stick water (SW) were extruded at different extrusion temperature profiles using a laboratory-scale single screw extruder. The ratios of SBM:RBC were 90:10, 85:15, and 80:20 on a dry basis. The ratio of SBM:SW was 80:20 on a dry basis. Ground extrudates were analyzed for physical and nutritional properties which indicate the suitability of each treatment for use in feed processing systems. As screw speed increased from 60 to 120 rpm, the protein digestibility of the ground extrudates from the blends of SBM with 20% RBC increased from 94.4 to 97.1% at an extrusion temperature of 90C, and from 89.1 to 93.1% at an extrusion temperature of 130C. The protein digestibilities of the ground extrudates decreased as RBC content and particle size of the SBM increased. The protein digestibilities of the extrudates from the blends of SBM with RBC and SW decreased as extrusion temperature increased and screw speed decreased. The equilibrium moisture content of pelletized extrudates was lower than that of ground extrudates at each water activity tested. The extrudates from the blend of SBM with RBC had increased protein content and quality because of an improved balance of essential amino acids compared to SBM alone.