A comparative study of analytical methods for alkali-soluble β-glucan in medicinal mushroom, Chaga (Inonotus obliquus)

Crude β-glucan content in the medicinal mushroom Chaga (Inonotus obliquus) was measured by different extraction and analytical methods, and the results were compared. The alkali extraction (AE) method or enzymatic digestion (ED) method followed by a gravimetric analysis was employed to determine the crude β-glucan content. The amount of crude β-glucan in Chaga obtained by either AE or ED was 13.7 g/100 g or 15.3 g/100 g of the sample, respectively. Crude β-glucan content of Chaga obtained by the above preparation methods were corrected by chemical composition analysis and HPLC analysis. After composition analysis, the amounts of β-glucan measured in the 100 g Chaga samples were corrected to 10.1 g for ED and 10.7 g for AE method. β-glucan contents calculated by the amount of glucose in the HPLC analysis were 8.3 g/100 g and 8.1 g/100 g for ED and AE preparation methods, respectively. Although extraction method did not affect β-glucan content in Chaga as indicated by no significant difference (P>0.05) between extraction method, significant differences (P<0.05) were noted between the correction methods. The discrepancies of the result indicate a need for standardization of analytical method for β-glucan measurement in Chaga