Effects of light on the quality of honeysuckle during storage based on physico–chemical indicators and chemical composition

Abstract

Honeysuckle, as a medicinal and edible substance, has been widely used for thousands of years. However, its quality is easy to change during storage by strong light, high temperature, high humidity and other inappropriate conditions. In this study, taking light as an example, the quality changes of honeysuckle during storage were explored by simulated accelerated test. The results showed that after 18 days of storage under light (6000 ± 10 Lx), the color changed from green-white to yellow-white, and the color parameter showed that a* value increased from 0.522 to 4.061, and L* value increased from 68.51 to 75.05. The contents of chlorophyll a, chlorophyll b, and carotenoid decreased by 90%, 78.67, and 75.69%, respectively. Total phenol content decreased from 18.200 to 13.087 GAE mg·g−1, although total flavonoid and antioxidant activities fluctuated without significant difference. Except quercetin, chlorogenic acid and other nine bio-active compounds contents fluctuated and increased, resulting in higher contents after storage than before storage, which indicated that the honeysuckle still had good utilization value after discoloration. Combined with metabolomics technology, 22 different metabolites related to these changes were screened and identified, such as pheophorbide a, astilbin, and succinic acid. KEGG enrichment analysis showed that the oxidative decomposition of phenolic compounds and pigment components such as chlorophylls and carotenoid caused the chlorosis of honeysuckle. In summary, although the light caused the chlorosis of honeysuckle, it didn’t affect the utilization value. Meanwhile, this also systematically explains why the Chinese pharmacopoeia describes the character of honeysuckle as “green-white or yellow-white”.