Green hot pepper (Capsicum annuum. L) is one of the most important crop in the world. However, they are subject to problems of price fluctuations and long-term storage. Meanwhile, the demand for new natural seasoning has been increased as dietary life becomes diversifying recently. Production of green hot pepper powder may be one of the solutions to meet the needs of novel condiments. This study was carried out to research drying condition for green hot pepper powder using vacuum drying and hot-air drying and to find the optimum storage temperature and period of fresh hot pepper for the powder production.

1. Quality characteristics of dried green hot pepper powder according to drying methods
Vacuum drying (VD, 640 mmHg) and hot-air drying (HD) were adapted for drying method of fresh green hot pepper (cheongyang cv.). VD was treated at 35, 40, 45℃ and 45℃ after 80% dried at 40℃ and HD was treated at 40, 50, 60℃ and 60℃ after 80% dried at 50℃. Peppers were cut 3 cm size. Quality of the dried peppers and pepper powder examined after drying.
In both drying methods, occurrence of seed browning and flesh browning increased as temperature increase and epidermis whitening occurred at low temperature (35℃ VD and 40℃ HD). Total chlorophyll contents were reduced for flesh browning, but were independent of epidermis whitening. The color of green hot pepper powder dried at 40℃ VD and 50℃ HD showed excellent green color. 35℃ VD and 40℃ HD samples were good green color with little paling because of epidermis whitening. Water absorption index (WAI) increased at low temperature but water solubility index (WSI) showed no difference. Capsaicinoids which are responsible for spicy taste of pepper showed no difference in drying temperature but vitamin C contents were higher 40℃ VD samples than 50℃ HD samples. In summary, quality of the dried peppers and powders were excellent for 35℃ VD, 40℃ VD, 40℃ HD and 50℃ HD samples. Considering the economical aspect, 40℃ VD and 50℃ HD conditions are adequate for drying fresh green hot peppers.
4 different cut (whole, 3 cm, 0.5 cm, longitudinal cut) peppers were dried 40℃ VD and 50℃ HD. Extents of seed browning and flesh browning increased as cut size increased and that of epidermis whitening increased as cut size decreased. 0.5 cm and 3 cm cut were found to be good cutting type for high quality green hot pepper powder.
From the result of this research to find proper drying temperature and cutting type using VD and HD, it is found that VD at 40℃ and HD at 50℃ combined with 0.5 cm and 3 cm cut, respectively, are the best drying condition considering quality of green hot pepper powder, economic feasibility and process convenience.
Fresh green hot peppers were divided into yellow-green (YG), green (G), and dark green (DG) by depth of green color. After 40℃ vacuum drying, chlorophyll contents were found in the order of YG, G and DG in increasing order. Extents of seed browning were similar with each other, however, the extents of flesh browning and epidermis whitening is lower in YG samples than the others. Visual inspection of the green hot pepper powder were similar quality with slightly bright green color with YG samples.

2. Quality characteristics of dried green hot pepper powder according to stored fresh pepper.
Fresh peppers were stored at two temperatures of 4℃ and 10℃. Measurements were performed at 10, 20 and 30 days after the storage, and the peppers were vacuum-dried at 40℃. Peppers stored at 4℃ showed green color and freshness, but chilling injuries (seed browning, pitting and fruit stalk softening) occurred more than 10℃ storage. Peppers stored at 10℃ showed some degradation in quality as storage period passed. However, they were subject to less chilling injuries than those stored at 4℃. The quality of pepper powders were maintained until 10 days for both storage temperatures. 20 and 30 days storage samples at 4℃ showed slight browning due to chill injuries, while 10℃ storage samples showed pale green color due to epidermis whitening. Therefore, when storing green hot pepper with the purpose of drying, optimum storage period for high-quality green hot pepper powder is 10 days at 4℃ and 20 days at 10℃.