Effect of Peppermint Oil on the Storage Quality of White Button Mushrooms (Agaricus bisporus)

White button mushrooms (Agaricus bisporus) were treated with 5 mu l L-1, 10 mu l L-1, 20 mu l L-1, and 50 mu l L-1 peppermint oil and then stored at 4 degrees C for 8 days to investigate with respect to browning and postharvest qualities. It was found that 20 mu l L-1 peppermint oil treatment could provide the best effect on inhibiting browning of fruit bodies. Our results indicated 20 mu l L-1 peppermint oil fumigation restrains browning development and alleviated membrane lipid peroxidation, as reflected by lower electrolyte leakage (17.42%), malondialdehyde (MDA) content (21.95%), and weight loss (1.69%) compared with those of the control mushrooms at 8 days, respectively. In addition, the 20 mu l L-1 peppermint oil fumigation had 1.49-fold and 1.24-fold higher phenolics and flavonoids accumulation respectively than those in control and retained high levels of soluble protein and total sugar at the end of the storage time. Furthermore, peppermint oil treatment significantly improved the antioxidant system, which increased the activity of superoxide dismutase (SOD) and phenylalnine ammonia lyase (PAL), and inhibited the activity of polyphenol oxidase (PPO) and peroxidase (POD), as well as regulated the relative expression levels of genes encoding polyphenol oxidase (AbPPO1, AbPPO2, AbPPO5, AbPPO6) and phenylalanine ammonia lyase (AbPAL1, AbPAL2) during the storage period. These findings suggest that peppermint oil fumigation is a promising method to control browning and improve the quality of button mushrooms.