Abstract:
To investigate the effects of different pretreatment methods on the drying rate and quality of vacuum freeze-drying chanterelles, this study systematically compared four techniques: Microwave Pretreatment (MP), Blanching Pretreatment (BP), Osmotic Pretreatment (OP), and Hot Air Pretreatment (HP). The effects of these pretreatments were evaluated based on several indicators, including drying characteristics, microstructure, rehydration capacity, color difference, total phenol and flavonoid content, antioxidant capacity, free amino acid content, and volatile flavor composition. The results demonstrated that, compared to the control group (which required 16 hours of drying), the drying durations of MP, BP, OP, and HP were shortened to 13, 11, 11 , and 13 hours, respectively. MP, BP, and OP significantly damaged the cellular structure of chanterelles, resulting in reduced levels of total phenols, total flavonoids, antioxidant activity, and free amino acids. In contrast, HP better preserved the tissue structure and led to increases in total phenol content, DPPH scavenging activity, ABTS
+ scavenging activity, and free amino acid content by 12.33%, 30.38%, 51.15%, and 59.86%, respectively. Furthermore, the number of volatile flavor compounds increased by 8, 4, and 4 types in the HP, BP, and OP groups, respectively. However, the total content of volatile flavor compounds declined in MP, BP, and OP, with only HP exhibiting an overall increase. Notably, key flavor constituents such as 1-octene-3-ol, trans-2-octenal, and 2-pentylfuran increased by 13.32%, 332.03%, and 184.44%, respectively. In terms of product quality, the rehydration capacity and color retention of chanterelles subjected to HP and MP were superior to those treated with BP and OP. Overall, Hot Air Pretreatment (HP) emerged as the more effective pretreatment method for vacuum freeze-drying chanterelles, providing a valuable reference for improving the quality and industrial processing of dried edible fungi.