Homogenate Extraction of Polysaccharides from Pine Nut Meal: Optimization and Comparison with Other Extraction Methods by Characterizing Their Extracts

Abstract

Homogenate extraction technology was applied to extract polysaccharides from pine nut (Pinus koraiensis) meal, a food waste from its oil processing. The first objective was to study the effects of liquid-solid ratio, homogenate extraction time, and temperature on the yield of pine nut meal polysaccharides (PNMP) using single-factor and Box–Behnken design. The optimal processing conditions were liquid-solid ratio of 43.23 mL/g at 35°C for 2 min 50 sec that produced PNMP yield of 11.7%. Extraction factors interacted with each other significantly (p<0.01). The second objective was to compare the homogenate extract with those produced using other methods including ultrasonic, microwave, and hot water extraction. Polysaccharides were separated using HPLC based on molecular weight (MW) and characterized with the polysaccharide and protein contents of each fraction. The homogenate PNMP had the most of small size (<100 kDa) polysaccharides, and its glycoprotein fractions generally contained higher level of protein, as well as a high ABTS+ scavenging activity observed by HPLC-UV-ABTS+ assay. FTIR analysis was used to characterize the functional groups. Homogenate extraction is superior in producing PNMP compared with other common methods, and its PNMP extract has potential antioxidant benefit.