Characterization of Moisture Transformation and Distribution in Mushroom (Lentinus edodes) During Hot-Air Drying

Abstract

Dehydration is widely used for shelf‐life extension of mushrooms. We examined the moisture distribution and transformation mechanism in mushrooms (Lentinus edodes) during process with six different hot‐air drying methods, including isothermal drying, uniform rise drying, nonuniform rise drying, uniform intermittent drying, nonuniform intermittent drying and combined drying. Nuclear magnetic resonance and 2D proton density imaging were used to analyze moisture transformation and distribution during the whole drying processes. The results showed that freezable and nonfreezable moisture were active while bound moisture was stable during drying processes. The key step to improve drying efficiency is to accelerate moisture transform from nonfreezable moisture status into freezable status. Combined drying was finally selected as the best treatment due to the observed homogeneous moisture distribution and its positive effect on mushroom's sensory quality. Practical Application Moisture content and status (free water and hydroxyl bond water) are the key parameters that affect the dehydrated foods such as dehydrated mushroom. As known, hot‐air drying is commonly used in the dehydrated mushroom process, including isothermal drying (ID), combined drying (CD), etc. It is very critical to find out the difference in dehydration mechanism of the mentioned methods, and make clear how these mechanisms finally affect the moisture content and status of mushroom, and find out the principle that water transformation mechanism. Because these mechanisms may also affect the drying efficiency, finally affect the quality of dehydrated mushroom. So the present research focus on the details that happened during drying process use NMR and 2D proton density imaging, especially the moisture distribution and transformation mechanism, by which we hope to give the industry a basic guidance while face different hot‐air drying methods and different product requirements.

Effects of contact ultrasound &far‐infraredradiation strengthening drying on water migration and quality characteristics of taro slices

“…It indicated that the water content of the samples decreased and the water mobility decreased, and the water with high degree of freedom migrated to the water with low degree of freedom. This was basically consistent with the results of Lu et al (2017) on lentinus edodes moisture content under different hot air drying conditions. After drying, the moisture content of taro was mainly bound water.…”

Characterisation of moisture migration of shiitake mushroom (Lentinula edodes) during storage and its relationship to quality deterioration

“…Yang et al () investigated the moisture distribution of Lentinus edodes during hot‐air drying to explore the mechanism of lignification and found that the decrease in mobility and population of free water and immobilised water had close relation with the lignification. Lu et al () examined the moisture transformation mechanism of mushrooms ( Lentinus edodes ) with six different hot‐air drying methods using LF‐NMR and MRI and found that combined drying resulted in homogeneous moisture distribution. Zhao et al () compared the influences of far infrared radiation and hot‐air drying on the moisture migration of shiitake mushrooms by LF‐NMR and MRI and found far infrared radiation drying resulted in a quicker decrease in peak area than hot‐air drying.…”

Measurement of moisture transformation and distribution in Tricholoma matsutake by low field nuclear magnetic resonance during the hot-air drying process

“…As shown in Figure b,c, the signal intensity decreased gradually in the area close to the surface and most exposed to drying. This phenomenon was also observed during the drying process of the mushroom ( Lentinus edodes ) (Lu, Guo, Li, & Ming, ). Intracellular moisture exhibited a lower migration rate than surface moisture.…”