In the AD process, drying rate decreased along with decreasing of edamame moisture contents and drying air temperatures, which might be attributed to slower moisture migration rate from interior to surface and evaporation
rate from surface to air caused by decreased sample moistures. At the same air velocity, the drying times required at
60, 70, 80 C were 600, 540, 360 min, respectively (Fig. 2). But higher temperature and longer drying time will cause
deterioration of edamame color and nutrients. Case hardening is another drawback encountered in hot-air dried products. Therefore, extremely high air temperatures should be avoided to minimize damages to the finished product quality. The AD process is divided into two phases. The early stage of drying characterized by higher drying rate could be explained by the ease of the free water at or near the surface to be removed. The least efficient portion of a conventional drying system is near the end, where the drying rate is controlled by water diffusion from interior to the surface, and sample shrinkage restricts the diffusion rate causing decreases in the drying rate. Generally, around two thirds of the drying time may be spent removing the last one third of the moisture contents to be reduced (Ana, Cristina, & Pedro, 2004), which makes hot air drying a time-consuming task.
In the AD process, drying rate decreased along with decreasing of edamame moisture contents and drying air temperatures, which might be attributed to slower moisture migration rate from interior to surface and evaporationrate from surface to air caused by decreased sample moistures. At the same air velocity, the drying times required at60, 70, 80 C were 600, 540, 360 min, respectively (Fig. 2). But higher temperature and longer drying time will causedeterioration of edamame color and nutrients. Case hardening is another drawback encountered in hot-air dried products. Therefore, extremely high air temperatures should be avoided to minimize damages to the finished product quality. The AD process is divided into two phases. The early stage of drying characterized by higher drying rate could be explained by the ease of the free water at or near the surface to be removed. The least efficient portion of a conventional drying system is near the end, where the drying rate is controlled by water diffusion from interior to the surface, and sample shrinkage restricts the diffusion rate causing decreases in the drying rate. Generally, around two thirds of the drying time may be spent removing the last one third of the moisture contents to be reduced (Ana, Cristina, & Pedro, 2004), which makes hot air drying a time-consuming task.
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