Characterization of Oligosaccharides in High Shear Pretreated Soybean Meal

Abstract

Because the USA is one of the largest producers of soybeans in the world, it also produces large quantities of defatted soybean meal (DSM), a major by-product of soybean processing. DSM has considerable amount of flatulence-causing oligosaccharides along with a small amount of cellulosic fiber. The primary purpose of pretreatment is to make the cellulosic biomass amenable to the action of the cellulose enzyme. Extrusion is an unexplored pretreatment but one that can be used on a commercial scale if more research is done. In this research, we studied the use of extrusion pretreatment on the enzymatic hydrolysis of DSM. The feedstocks were pretreated in a lab-scale single-screw extruder. The effects of barrel temperature, screw speed, and moisture content of the materials on sugar recoveries were investigated. The extruder was operated at predetermined barrel temperatures, screw speeds, and feedstock moisture contents, which were selected based on preliminary trials. The extruded samples were subjected to subsequent enzymatic hydrolysis, and sugars were measured using HPLC. Statistical analyses found that the extruder parameters and moisture content of feed materials had an influence on the sugar recovery from the studied materials. For DSM, the optimum pretreatment conditions were 20% moisture content, 175 C, and 50 rpm for 84% recovery.