Influence of heat treatment on the antioxidant activities and polyphenolic compounds of Shiitake (Lentinus edodes) mushroom

The effect of heat treatment on the changes in the overall antioxidant activity and polyphenolic compounds of Shiitake extract was investigated. Raw Shiitake was heated at 100 and 121 degrees C for 15 or 30 min using an autoclave. After heat treatment, the free and bound polyphenolics and flavonoids in the mushroom extracts were analyzed. 2,2-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical and 1,1-diphenyl-2-picrythydrazyl (DPPH) radical scavenging activities were measured to evaluate antioxidant activity of the extracts. The polyphenolic contents and antioxidant activities in the extracts increased as heating temperature and time increased. For example, the free polyphenolic content in the extract heated at 121 degrees C for 30 min was increased by 1.9-fold compared to that in the extract from the raw sample. The ABTS and DPPH radical scavenging activities were increased by 2.0-fold and 2.2-fold compared to the raw sample, respectively. There was a good correlation between total polyphenolic contents and AEAC (P < 0.001). Results showed that heat treatment significantly enhanced the overall antioxidant activities of Shiitake mushroom. (c) 2005 Elsevier Ltd. All rights reserved.