Chemical properties Figure 1 showed the chemical properties data. The pH values, sucrose, alcohol and acid contents during period of heating times (0–56 sec) were not significantly different (P>0.05). Microwave drying at the short heating times do not affect the loss of water-soluble components (Maskan, 2000). Kadlec et al. (2001) studied on the effect of microwave heating on the changes of soluble carbohydrates during germination of pea seeds (Pisum sativum). The results showed that soluble carbohydrate was not significantly decreased. In addition, considerable increase of antioxidant such as total phenolic and flavonoids contents in mash apple through microwave heating caused from the evaporated water from sample which concentrated the inner substances (Gerard and Roberts, 2004). However, the longer heating times by microwave caused the decrease of moisture contents (Figure 1b). The sample of 56 sec treatment showed the lowest moisture contents (52.78%). It is because of the moisture in food matrix vaporize out and absorb microwave energy directly and internally and convert to heat. In microwave heating, heat is generated throughout the material and leading to faster heating rates where heat is usually transferred from the surface to the interior (Gowen et al., 2006). Hence, microwave heating is caused by water vapor pressure differences between interior and surface regions, which provide a driving force for moisture transfer (Vadivambal and Jayas, 2007).