Dynamic variation of the phytochemical and volatile compounds in the pericarp of Citrus reticulata ‘‘Chachi’’ (Rutaceae) during 2 years of storage

The pericarp of Citrus reticulata "Chachi" (CRCP) is used as nutritional food and traditional medicine in China, usually harvested at three periods, namely, immature (CRCP-G1), semi-mature (CRCP-G2), and fully mature (CRCP-G3). Traditionally, if the CRCP is stored for a longer period, then the quality will be better. In this study, the dynamic variation of phytochemical and volatile compounds was profiled in the same batches of CRCP during 2 years of storage. Results illustrated that most of the phytochemical compounds showed a decreasing trend during storage, that is, total flavonoids, total phenolic acids, hesperidin, 3,5,6,7,8,3',4'-heptamethoxyflavone, 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone, synephrine, and limonin. The ferulic acid increased significantly, whereas no significant changes were observed in the total polymethoxyflavones, nobiletin, and tangeretin after 2 years of storage. In addition, we found that the extraction yield of volatile oil decreased significantly in CRCP-G1 during storage, and the herb odors were enhanced with the increase of phenols and esters. No significant difference in the extraction yield of volatile oil of CRCP-G2 and CRCP-G3 was found after 2 years of storage, but the citrus-like notes were increased with the promoted generation of alkenes. In particular, the multivariate statistical analysis indicated that 7 volatiles showed a higher level after 1 year of storage, whereas 11 volatiles decreased and 4 volatiles increased after 2 years of storage, respectively. This study could show the early aging mechanism of CRCP harvested at different periods and provide a scientific guidance in the storage of CRCP. PRACTICAL APPLICATION: This study indicated a comprehensive method for rapid analysis of phytochemical and volatile compounds in pericarp of Citrus reticulata ''Chachi'' (Rutaceae) (CRCP) harvested at different periods during 2 years of storage. The results obtained from this study would be valuable for revealing the early aging mechanism and sustainable storage of CRCP.