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Y. T. MA, Food and Nutritional Sciences, The Chinese Univ. of Hong Kong, Shatin, Hong Kong, 852, China and P. C. K. Cheung, Food and Nutritional Sciences Programme, The Chinese Univ. of Hong Kong, Shatin, New Territories, Hong Kong, China. Recent research has established the correlation between phenolics and antioxidant activity in fruits and vegetables. Our preliminary study has also found out such relationship in mushrooms. However, most of the edible mushrooms are easily deteriorated due to their high moisture content and enzymatic activities. Therefore they have to undergo thermal processing to extend their shelf life, particularly by canning and drying. The study of the effect of thermal treatment on phenolics and antioxidant activity was only limited to some fruits, in which a significant reduction in total extractable polyphenols with increasing temperature was found. The influence of canning and drying on phenolics and antioxidant activity of processed mushrooms were largely unknown. This project studies the influence of heat treatment including canning and drying on the phenolics and antioxidant activity of fresh mushrooms. Four fresh mushrooms commonly found in Asian cuisine including Agaricus bisporus, Lentinus edodes, Volvariella volvacea and Agrocybe aerigita were screened for the antioxidant activity of their alcoholic and water extracts. Subsequently, the mushrooms will be subject to different conditions of thermal treatments including canning and drying. The changes in the phenolics and antioxidant activities of the processed mushrooms will be investigated. Alcoholic extracts of A. aegerita, A. bisporus, and V. volvacea had the highest antioxidant activity against DPPH free radical with IC50 below 1 mg/ml. The Trolox equivalent antioxidant activity (TEAC) at 10mg/ml of L. edodes extracts was significantly lower than the others (p<0.05). Significant correlation was found between the total phenolic content and the antioxidant activity against DPPH (p<0.01) in most extracts of the four mushrooms. Similar antioxidant assays on the extracts of the processed mushrooms are underway. Through studying the processing effect on mushroom phenolics and antioxidants, the processing conditions can be optimized to preserve the antioxidant potency of the mushrooms.
Session 83, Food Chemistry: Antioxidant and bioactive agents
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |