열처리조건에 따른 숙지황의 품질변화

This study was performed to develop a more simple and convenient heat treatment process for increasing heating temperature than the traditional 9-times steaming process for Rehmanniae radix Preparata (R. radix P.). The R. radix was heated to various temperatures (110, 120, 130, 140 and 150℃) for different lengths of time (1, 2, 3, 4 and 5 hr). Chromaticity, free sugar, amino acid, catalpol and 5-HMF (5-hydroxy-methyl-2-furaldehyde) content of water extracts of R. radix P. were analysed. With increasing heating temperature and time, the L, a and b-value of samples gradually decreased. Fructose and glucose contents were increased to 120℃ for 5 hr (5.21 and 6.67%, respectively) with no changes afterward. Sucrose content was not detected after 130℃. Total amino acid was increased to 140℃ and decreased afterward. The maximum total amino acid content was 4,172 ㎎/100 g at 140℃ for 2 hr (R. radix L.: 3,029 ㎎/100 g). The catalpol was decreased to 130℃ for 1 hr and not detected afterward. The 5-HMF content increased with increasing heating temperature and time. The maximum content of 5-HMF was 2.5% in 150℃ for 5 hr. Hence, it can be suggested that the heat treatment at 130℃ for 2 hr or more is the most optimum processing conditions, instead of the traditional 9-times steaming process.