In the present study, four edible mushrooms, Lentinula edodes, Agaricus bisporus, Pleurotus ostreatus, and Pleurotus eryngii, were air-dried or freeze-dried for a certain period of time. After finely ground the materials, their beta-glucan contents were measured. Beta-glucan is a polysaccharide of plant and fungal cell wall and also a dietary fiber. It has an effect on stimulating immune cells and decreasing cholesterol. In the mushroom materials used in this study, beta-glucan contents were measured as 11-16%. Among them, P. ostreatus represented the highest contents, 16%. The authors also examined the contents of polyphenol, which is a phenolic compound known to have antioxidant activity. The polyphenol concentrations of the selected mushrooms were measured in 1 mg/ml of each sample prepared by hot-air drying and freeze-drying, respectively. As a result, 28-32 mg/ml of polyphenol was measured in hot air dried samples of P. ostreatus. In P. eryngii, air-dried samples had 6 mg/ml more polyphenols than freeze-dried ones, while in P. ostreatus, the former had 10 mg/ml more than the latter, indicating that the polyphenol contents in mushrooms can be changed by the different drying treatments. In other words, for P. eryngii and P. ostreatus, hot-air drying is more suitable processing method than freeze-drying in the light of physiological activity.

The total polyphenol and physiological activities of Pleurotus ostreatus 30% fermented ethanol using different drying methods and extraction periods were investigated. Based on the observed polyphenol content and physiological activity, freezedrying showed better results than hot air-drying method for P. ostreatus extracted with 30% fermented ethanol for more than 15 days. The total phenolic compound content of ‘Gosol’ following thefreeze-drying method for 15 days showed the highest value of 0.49±0.02 mg/mL. Freeze-drying with extraction for 30 days for ASI 2344 showed the highest antioxidant activity based on the DPPH radical scavenging rate of 35.50±3.29%. Freeze-drying ‘Gosol’ for 30 days resulted inthe highest anti-inflammatory and nitrite scavenging activity of 48.40±3.38%. Our results showed that P. ostreatus is a functional food.