Short-term O2/CO2 controlled atmosphere altered the water status and thus promoted phenolic biosynthesis during wound healing of fresh-cut white mushroom (Agaricus bisporus)

Abstract

High O2/CO2 treatment has shown to promote the wound healing of fresh-cut white mushrooms. However, the mechanism of water migration in wound healing under high O2/CO2 treatment is still ambiguous. In this study, the effects of 80% O2 + 20% CO2 treatment before or after cutting on the accumulation of phenolic compounds, phenylpropanoid metabolism, as well as the water status and distribution in fresh-cut white mushrooms were evaluated. The results indicate that compared with the control group, both high O2/CO2 treatments before or after cutting increased the content of phenolic compounds, flavonoids and lignin. Among the high O2/CO2 treatments, the treatment after cutting stimulated the phenylpropanoid pathway, elevated the levels of individual phenols including protocatechuic acid, gallic acid, hydroxybenzoic acid, p-coumaric acid, cinnamic acid, ferulic acid, quercetin, catechin, and kaempferol. Additionally, with a longer storage time, the results of low-field nuclear magnetic resonance (LF NMR) indicate that the amplitude of free water significantly decreased and immobilized while the amplitude of bound water increased in all treatments. The moisture content in fresh-cut white mushroom mainly depends on the free water content. High O2/CO2 treatment after cutting maintained the level of free water inside while decreased the level of free water on the surface of fresh-cut white mushroom. In conclusion, high O2/CO2 treatments after cutting effectively enhanced wound healing by promoting the loss of surface water. Moreover, the wound healing on surface inhibited the water mobility and transformation inside white mushroom slices, this maintaining the quality of fresh-cut white mushrooms.