Abstract: In this experiment, shiitake mushrooms was subjected to negative pressure osmosis treatment with different concentrations of spermidine (10, 15 and 20 mg/L), and then were stored at 4 ℃ for 16 days. The changes in hardness, the contents of lignin, chitin, cellulose and total phenolics, and the activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD) were examined during the storage period. Our results showed that none of the treatments could inhibit the decrease in hardness, although they all resulted in an increase in cellulose content. In addition, 15 mg/L spermidine treatment showed no significant decrease in chitin content during the late stage of storage, and total phenol content in all groups increased first and then decreased during the entire storage period. Both 15 and 20 mg/L spermidine treatments could maintain a low PAL activity from day 4 to 6 of storage. Furthermore, 20 mg/L spermidine inhibited POD activity between the fourth and sixth day and delayed the peak of lignification.

Key words: lignifications, shiitake mushrooms, cell wall, spermidine