Effects of UV-C on antioxidant activity, total phenolics and main phenolic compounds of the melanin biosynthesis pathway in different tissues of button mushroom

• Button mushroom tissues have different antioxidant activity and phenolic content.
• UV-C enhanced antioxidant activity and phenolic content of whole mushroom.
• UV-C decreased phenolic content in mushroom peel.
• The study provides insight in how UV-C causes mushroom browning.

The effect of 1.0 kJ/m2 ultraviolet-C (UV-C) light on antioxidant activity, total phenolics and main phenolic compounds associated with browning of button mushroom (Agaricus bisporus) tissues during 21 days storage at 4 °C was studied. The distribution of antioxidant activity and phenolic compounds varied significantly in different parts of button mushroom. The highest DPPH scavenging activity was investigated in the stipe, and the gill contained the highest concentration of total phenolics, γ-glutaminyl-4-hydroxybenzene (GHB) and γ-glutaminyl-3,4-dihydroxybenzene (GDHB). UV-C irradiation enhanced antioxidant activity, total phenolics and phenolic compounds in inner cap, stipe, gill and whole mushroom during storage compared to control. However, UV-C irradiated mushroom reduced the total phenolics, GHB, GDHB and tyrosine contents of the peel fraction compared to the control sample during the storage. Application of 1.0 kJ/m2 UV-C treatment could effectively induce the increase of antioxidant capacity and compounds in whole mushroom during storage, and likely lead to the oxidation and conversion of phenolic compounds in peel tissue which participate in the formation of melanin associated with browning of mushrooms.