| Abstract: | In the present study, we explored the correlation between 5-hydroxymethylfurfural (5-HMF) and color of Rehmanniae Radix (RR) and Rehmanniae Radix Praeparata (RRP). The color was observed by human eyes under sunlight. The chromatic value and color difference were detected by a colorimeter. The water content was determined by an oven-drying method. The 5-HMF content was determined by an HPLC method. The correlation between the 5-HMF content and the color was analyzed by bivariatecorrelation analysis. The results showed that the color was greyish-brown and dark brown for RR, and it was black for RRP. The deepening color of RRP was reflected in the decrease of L*, a* and b* values. The water content was in accord with the requirement of Chinese Pharmacopoeia. The 5-HMF contents of RR and RRP were 0.9711–25.71 µg/g and 213.4–4010 µg/g, respectively. The average 5-HMF contents of RR and RRP were 8.059 µg/g and 1433 µg/g, respectively. The 5-HMF content in RRP was higher than that in RR. The correlations between 5-HMF content and L*, a* and b* values were significant. The color of RRP was deeper than that of RR. The 5-HMF content of RRP was higher than 0.02%, while it was less than 0.02% of RR, which could be used as a marker component for judging RR and RRP. |
