Effect of exogenous glycine betaine on qualities of button mushrooms (Agaricus bisporus) during postharvest storage

In order to extend the storage life of button mushrooms (Agaricus bisporus), glycine betaine (GB) treatment was introduced and its effect on the quality and physiological characteristics of button mushrooms during storage was evaluated in the present work. Fresh button mushrooms were soaked with GB solutions of different concentrations and then stored at low temperature (2 A degrees C) for 12 days. The variations of weight loss rate, percent open caps and color of mushrooms were investigated. Physiological characteristics were evaluated during storage, including respiration rate, polyphenol content, malondialdehyde accumulation as well as activities of polyphenol oxidase enzyme (PPO) and antioxidant enzymes. Membrane permeability and microstructure was also analyzed by electrical conductivity and scanning eletron microscope (SEM) measurement. The results showed that the button mushrooms treated with GB kept a lower level of weight loss and respiration rate, the cap opening and browning were also inhibited. Meanwhile, treated samples maintained high content of polyphenol and ascorbic acid and showed better integrity of cell membrane structure. In addition, GB inhibited PPO activity and improved activities of antioxidant enzymes such as SOD, POD and CAT during storage period. The results of treatment group with 2 mM GB were significantly better with other treatment groups (p < 0.05), which was determined to be the suitable treatment concentration of GB to extend the storage life of button mushrooms.