Physicochemical Properties of Chaga (Inonotus obliquus) Mushroom Powder as Influenced by Drying Methods

The effects of drying methods on the physicochemical properties of chaga (Inonotus obliquus) mushroom powder were investigated. Scanning electron micrograph revealed that freeze drying produced smaller particlesized samples which in turn resulted in higher porosity than did vacuum and hot-air drying. Samples prepared by freeze drying showed a significantly higher L*-value as compared with those prepared by hot-air drying and vacuum drying (p＜0.05). The lightness (L*-value) significantly decreased with increasing relative humidity and storage temperature regardless of drying method (p＜0.05). The yellowness (b*-value) increased significantly with increasing relative humidity (p＜0.05). Browning index was significantly lower in samples prepared by freeze drying (p＜0.05) but not significantly different between samples dried by hot-air and vacuum drying. Freeze dried sample exhibited a significantly higher degree of rehydration than other samples (p＜0.05) probably due to the small particle size. Water solubility of the freeze dried sample was higher than those of the other methods while swelling ratio of the same sample appeared to be lower than those of others. Freeze dried chaga mushroom powder contained significantly lower amount of total phenolics and total sugar as compared to other samples (p＜0.05).