Preparation and coating application of γ-polyglutamic acid hydrogel to improve storage life and quality of shiitake mushrooms

γ-polyglutamic acid (γ-PGA) hydrogel was prepared by chemical crosslinking with polyethylene glycol diglycidyl ether (PGDE) as the crosslinking agent. Coating treatments with γ-PGA hydrogel improved the storage life and quality of shiitake mushrooms. Among them, 1.0% (w/v) γ-PGA hydrogel exhibited highest preservation effects during storage, compared with control and other treatments. Coating of 1.0% γ-PGA hydrogel significantly inhibited the decay, water and weight losses, and vitamin C degradation of shiitake mushrooms during storage. Meanwhile, it also obviously suppressed the polyphenol oxidase (PPO) activity, consequently inhibited the browning of shiitake mushrooms during storage. Moreover, shiitake mushrooms maintained good sensory qualities by coating of 1.0% γ-PGA hydrogel, and extended its storage life to 30 days at 4 °C. These results indicated the coating application potential of γ-PGA hydrogel in industrial preservation of shiitake mushrooms. • γ-PGA hydrogel was prepared by polyethylene glycol diglycidyl ether crosslinking. • Coating of γ-PGA hydrogel inhibited the browning of shiitake mushrooms during storage. • Coating of γ-PGA hydrogel ameliorated the storage quality of shiitake mushrooms.