DisplayTitle

Small-Scale Extrusion of Corn Masa By-Products

¹Agricultural and Bioprocess Engineer, USDA, ARS, NGIRL, Crop and Entomology Research Unit, Brookings, SD, USA. ²Corresponding author. Phone: (605) 693-3241. Fax: (605) 693-5240. E-mail: krosentr@ngirl.ars.usda.gov ³Associate professor, and professor, Agricultural and Biosystems Engineering Department, Iowa State University, Ames, IA, USA. ⁴Research food engineer, USDA, ARS, Eastern Regional Research Center, Wyndmoor, PA, USA.

Corn masa by-product streams are high in fiber and are amenable for utilization in livestock feed rations. This approach is a potentially viable alternative to landfilling, the traditional disposal method for these processing residues. Suspended solids were separated from a masa processing waste stream, blended with soybean meal at four levels (0, 10, 20, and 30% wb), and extruded in a laboratory-scale extruder at speeds of 50 rpm (5.24 rad/sec) and 100 rpm (10.47 rad/sec) with temperature profiles of 80-90-100°C and 100-110-120°C. Processing conditions, including dough and die temperatures, drive torque, specific mechanical energy consumption, product and feed material throughput rates, dough apparent viscosity, and dough density, were monitored during extrusion. The resulting products were subjected to physical and nutritional characterization to determine the effects of processing conditions for these blends. Extrudate analysis included moisture content, water activity, crude protein, in vitro protein digestibility, crude fat, ash, product diameter, expansion ratios, unit and true density, color, water absorption and solubility, and durability. All blends were suitable for extrusion at the processing conditions used. Blend ratio had little effect on either processing parameters or extrudate properties; extrusion temperature and screw speed, on the other hand, significantly affected both processing and product properties.