This study aimed to economically produce high quality of dried kimchi through a cyclic low pressure drying device in order to overcome the disadvantages of the conventional drying process. The moisture content of dried kimchi obtained from the cyclic low pressure drying process was found to be uniformly reduced according to drying time. Also, cyclic low pressure drying showed the shortest change and a stable reduction in drying rate. Further, cyclic low pressure drying did not markedly change pH, titratable acidity, or salt content. In addition cyclic low pressure drying compared with fresh kimchi showed the similar color values and maintained the flavor of the kimchi. In conclusion, cyclic low pressure drying resulted in superior rehydration and sensory scores.

This study was performed to maintain the biological activities of fresh ginseng during the drying processes. To obtain this purpose, a balanced low pressure drying process was employed to dry fresh ginseng at low temperature and pressure. This process requires a longer process time than that of hot air drying, but much lower temperature. This system is also economically feasible as it requires lower input energy than freeze drying and maintains similar biological activities such as acidic polysaccharides, because these polysaccharides were known to be heat labile and also resulted in lowering the biological activities of ginseng extract. It was also found that the higher process time and temperature of hot air drying significantly reduced volatile biologically active components such as phenolic compounds, which resulted in lowering the antioxidant activities of ginseng extract. Furthermore, the liquid extracts from ginseng dried by the balanced low pressure drying process increased the growth of human B and T cells, also increased secretion of both IL-6 and TNF-α. These results demonstrate that low pressure drying under balanced air condition could reduce the degradation of ginseng by preventing the breakdown of heat labile biologically active components, not ginsenosides. It could eventually improve the biological activities of fresh ginseng.