Effects of pre-cutting treatments and combination drying with different orders on drying characteristics and physicochemical properties of Lentinula edodes.

BACKGROUND Combination drying is recognized as an energy-efficient method utilized for dry product processing, and proper order of combination is a critical factor determining the effectiveness of the technique. In this study, hot air-drying (HD), vacuum freeze-drying (VFD), and combination drying with different orders (HD-VFD and VFD-HD) are performed to whole Lentinula edodes and pre-cutting (half-cut and quarter-cut) L. edodes. The effects of various cutting and drying approaches on drying characteristics, physicochemical properties and microstructures of dried L. edodes were investigated. RESULTS The longest processing time required to dry the whole L. edodes by VFD was 25 h. In contrast, the pre-cutting treatment and combination drying certainly shortened the drying time. Compared with HD, VFD-HD and VFD significantly decreased the shrinkage ratio, hardness, and discoloration of dried products but increased the rehydration capacity, nutrient retention, and porous microstructure. Interestingly, switching the order of combination drying provoked entirely different drying effects. Specifically, HD-VFD triggered negative effects on the shrinkage and color of dried mushrooms, and its appearance color was similar to HD-treated samples. Moreover, pre-cutting dramatically enhanced the protein content of HD-treated mushrooms, and the quarter-cut samples obtained the highest level (21.69 g kg-1 dry base) among the three types of cutting. CONCLUSIONS The dried L. edodes processed through pre-cutting and combination drying (VFD-HD) have optimal industrial quality, accompanied by shorter processing time. This article is protected by copyright. All rights reserved.