Abstract: The fresh-keeping effects of citric acid, phytic acid, vitamin C, chitosan and salt on Pleurotus ostreatus were comparatively investigated, and citric acid, phytic acid and vitamin C showed relatively stronger effect. Then a composite preservative consisting of the above three compounds at different concentrations was developed, and its fresh keeping effect was evaluated by measuring weight loss, degree of browning, respiratory intensity and sensory indexes (including color, smell, viscosity, degree of decay, etc.) of composite-preservative-treated Pleurotus ostreatus during storage at 8 ℃. Results showed that when used separately, the optimum concentration ranges of citric acid, phytic acid and vitamin C were 5－10, 1.5－2.0 g/L and 0.9 － 1.3 g/L, respectively, and when formulated, their optimal concentrations were determined by orthogonal array design experiments to be 10, 1.5 g/L and 1.3 g/L, respectively.

Key words: Pleurotus ostreatus, complex preservatives, fresh-keeping, weight loss rate, degree of browning, respiratory intensity