Storage of mushrooms (Agaricus bisporus, [Lange] Sing.) in 0% O2 reduced discoloration and o-diphenol oxidase (o-DPO) activity for up to 7 days. Levels of O2 above 0% had little or no effect in reducing discoloration and o–DPO activity compared to air controls. Concentrations of CO2 above 5% appeared to increase surface discoloration while markedly inhibiting o-DPO activity. After transfer to air, the effectiveness of the increased CO2 treatments in reducing o-DPO activity in mushrooms depended on storage time in CO2.
In vitro CO2 markedly inhibited o-DPO activity, with 50% inhibition at 25% CO2. Complete inhibition was never attained. The inhibition by CO2 was found to be competitive with respect to catechol and could not be overcome by increasing the O2 concentration above 20%. The action of CO2
in vivo in reducing o-DPO activity could be through a direct competitive inhibition or through the inhibitory effect of CO2 on mushroom maturation.