Effect of extrusion process on antioxidant activity, total phenolics and p-glucan content of extrudates developed from barley-fruit and vegetable by-products

摘要

The aim of this study was to determine the effects of extrusion processing variables on antioxidant activity (AA), total phenolic content (TP) and β-glucan content (BG) of extrudates. Products were prepared by extrusion cooking of barley flour, barley flour-tomato pomace and barley flour-grape pomace blends. Antioxidant activity as measured by the DPPH method was 43.17 ± 0.362, 27.57 ± 0.120 and 82.23 ± 0.785% while TPs, expressed as ferulic acid equivalents, were 5.29 ± 0.126, 4.66 ± 0.023 and 9.15 ± 0.015 mg g~(-1) dry sample in the extracts obtained from barley flour, tomato and grape pomaces, respectively. Extrusion cooking decreased AA and TP of barley, barley-tomato pomace and barley-grape pomace extrudates. Temperature and screw speed had significant (P < 0.05) effect on BGs of barley flour and barley-grape pomace extrudates. However, BG of tomato pomace blend extrudates had significantly (P < 0.05) influenced from pomace level only. Results indicated that the content of P-glucan is higher in barley flour than in extrudates of barley flour and pomace blends.