## 3 Results and Discussion
### Reduction in Dehydration and Rehydration Times  
As microwave drying is generally appropriate for low-moisture foods, it takes a long time to dehydrate fresh stink beans with the moisture exceeding 70%. In addition to the increase in temperature shown in 3.1, the dehydration time by microwave can be shortened by the reduction in pressure during drying. Vacuum pressure and higher microwave power produce more pores without increasing shrinkage [41]. It follows that the diffusion of water through rehydrated products is increased.  
The low pressure of 400 Pa during microwave drying gives rise to dark green products comparable to those dehydrated by microwave at the increased temperature of 40 \({}^{\circ}\)C. As compared in Table 3, the reduction in pressure from 101 kPa to 400 Pa decreases the dehydration time from 10 h to 6 h. However, the rehydration still needs around 65 min. In both cases, the color of seed coats greatly changes after the rehydration. As compared in Table 4, the CIE L\({}^{\star}\) value is almost doubled, consistent with the change from dark to lighter in color. The effect of pressure during microwave drying is shown by the CIE a\({}^{\star}\) and b\({}^{\star}\) values. As a result of drying at a lower pressure of 400 Pa, a\({}^{\star}\) is smaller and b\({}^{\star}\) is larger corresponding to the color closer to that of fresh stink beans. Moreover, the shape  
Figure 2: FESEM images of dried stink beans from (**a**) Convective drying (60 \({}^{\circ}\)C), (**b**) Freeze drying (\(-\)70 \({}^{\circ}\)C), (**c**) Microwave drying (35 \({}^{\circ}\)C), and (**d**) Microwave drying (40 \({}^{\circ}\)C).  
The moisture content of 11.3% in Table 4 highlights the effect of low pressure on the microwave drying of sink beans that more water content is removed within a shorter time. The crude protein in sink beans dehydrated by using ambient and low pressures is comparable around 30%. As the combined uncertainty from the sample preparation and protein analysis method can be as high as 1%, these protein values are considered unchanged from those of the fresh sink bean, highlighting that the relatively low temperature in microwave drying could preserve the high protein present in sink beans [47]. In this work, the crude protein of dried stink beans is measured exclusively in the case of microwave drying at 35 \({}^{\circ}\)C because the proteins are likely degraded by drying at higher temperatures [68; 69]. As demonstrated by [PERSON] et al. [61], the protein in quinoa seeds was reduced by 10% after convective drying at 40-80 \({}^{\circ}\)C. The report on squid shreds indicated that microwave drying slightly affected the protein content [42].  
Finally, the rehydration time is significantly reduced by increasing the water temperature. As shown in Table 5, the products fully restore their original shape and color after immersion in 50 \({}^{\circ}\)C and 70 \({}^{\circ}\)C for, respectively, 40 min and 30 min. The measurements on seed coats in Table 5 show some similar trends to those in Table 3. The rehydrated products exhibit increases in L* and b* values. However, the a* value is only reduced in the case of 50 \({}^{\circ}\)C, suggesting that the major change after rehydration is not the greenness but the lightness component. Furthermore, both values are increased with increasing temperature in the rehydration. The reduction in rehydration time is consistent with the suggestion in the literature that a higher temperature increases water absorption as well as the rehydration rate [28]. After a rapid rise in water due to the initial moisture difference, the reductions in viscosity and the surface tension of water at elevated temperature are increasingly influential