Generally, sweet potato is cooked either by boiling, steaming or roasting, before consumption. The thermal processing can cause impairment of the functional compounds of sweet potato. There have been reports of negative correlation between heat treatments (steaming and baking) and some bioactive substances, such as anthocyanins. The shelf life of the sweet potato is in weeks and not longer than the few other roots, and therefore, it is difficult to stockpile in farms. The usually picked and eaten during the short period of the harvesting season. Thus, an extension of its shelf life would make it possible to lengthen the period of commercialization, as well as improving food safety and economic values. Due to these factors, the sweet potato should be eaten within a few weeks after harvest, or processed to reduce its moisture content, which allows it to be stored for a longer period of time. They are usually dehydrated after slicing to improve the efficiency of the process (Chen, 2002). It is a well-known fact that in some areas the root is sliced and dehydrated to increase conservation (Oirschot et al., 2003).