Antioxidant Capabilities of Defatted Soy Flour Extracts

摘要

Antioxidant activities of defatted soy flour extract and the extract treated with heating or (3-glucosidase hydrolysis were evaluated using a menhaden oil oxidation model. The defatted soy flour extract (5 % in oil) demonstrated the capability of reducing menhaden oil oxidation products and retaining over 60% of DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) after the oil was heated at 150°C for 30 min, while only 30% of DHA and EPA in the control oil model. The level of rancid volatile, hexanal, in the menhaden oil mixed with the extract was significantly reduced during storage at room temperature as well. The isoflavones with glucoside in the extract were significantly converted to their corresponding aglycone isoflavones at 150°C for 30 min with less thermal degradation or by (3-glucosidase hydrolysis. The antioxidant activities of the heated and enzyme treated extracts were significantly higher than the original extract. After 4 days storage at room temperature the retained EPA and DHA in the menhaden oil were over 60% with the enzyme treated extract and 30% with the heat treated extract, while approximately 15% were remained in the fish oil with the original extract.