Abstract:

In the present study, the fresh fruiting bodies of shiitake mushroom (Lentinus edodes) were cut into caps and stipes
and then either processed into powders with different sizes by coarse milling, jet milling and nano-grinding after drying.
The differences in the dissolution rate and composition of phenols and antioxidant activity of dried mushroom powder
after purification were evaluated in comparison with the ordinary powder. Compared with ordinary grinding, the superfine
grinding could increase the dissolution rate of total phenols by up to 13%. The profile and concentrations of individual
phenolics were determined by high performance liquid chromatography (HPLC). The results showed that the main individual
phenolics in mushroom powder were gallic acid, catechin, caffeic acid, rutin, ferulic acid and quercetin. In addition, the main
compounds were gallic acid and catechin in free polyphenols, and gallic acid, catechin and quercetin in bound polyphenols.
Our results also suggested that jet milling could obviously enhance the reducing power, 2,2’-azino-bis(3-ethylbenzthiazoline-
6-sulfonic acid) (ABTS) free radical scavenging activity and oxygen radical absorbance capacity of polyphenols in the
mushroom powder, while nano-grinding could improve 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging
activity of polyphenols in the stipe powder. In conclusion, superfine grinding could increase both polyphenol content
and antioxidant activity of mushroom products. Overall, jet milling could be used as a means of pretreatment to develop
functional foods with mushrooms.

Key words: Lentinus edodes, phenolic, superfine grinding, antioxidant activity, high performance liquid chromatography (HPLC)