Program temperature-controlled drying: An effective way to improve the quality of hot-air dried shiitake mushrooms

This study applied program temperature-controlled drying (PTCD) to optimize the hot-air drying process for shiitake mushrooms, adjusting the drying temperature based on activity changes of γ-glutamyl transpeptidase (γ-GTase) and cysteine sulfoxide lyase (C-S lyase). Compared with constant temperature drying, PTCD (ST_75 and ST_150) significantly enhanced the umami and aroma profiles and sulfur compounds, increasing the levels of key flavor compounds such as glutamic acid and 5'-GMP. Moreover, PTCD improved rehydration capacity (515.17%) and reduced shrinkage (12.43%) for ST_150 samples, achieving superior texture and color retention. Nutritional analysis indicated that PTCD better preserved nutrients such as ergothioneine, ergosterol, and purines, with ergosterol content reaching 9953.22 µg/g in the ST_150 group. This study provides theoretical support for improving the quality of hot-air-dried shiitake mushrooms in industrial applications. PRACTICAL APPLICATION: Although hot air drying is widely used for mushrooms, it is typically conducted using constant temperature methods. The application of PTCD and its effects on mushroom product quality have been scarcely studied. This study proved that compared with constant drying temperature, PTCD could significantly improve the flavor, texture, and nutrition retention of dried products. This may provide scientific foundation for the industrial application of hot air drying of shiitake mushrooms with improved quality.