Change Patterns of Major Functional Components in the Loquat Summer Shoot Leaf during Annual Growth

Loquat leaves are widely used in traditional Chinese medicine and food processing as raw materials. To provide a theoretical basis for suitable harvesting periods based on the utilization of distinct components, the change patterns of major functional components in the annual growth of loquat leaves were investigated. In this study, the summer loquat leaves were sampled regularly during their annual growth, and the contents of seven main functional components and 13 monomer components were determined. The results showed that there was a regular change pattern for major functional components during loquat annual growth from Jul 2020 to Jun 2021; however, the change trend was different among different components. Among them, the contents of total flavonoids, total phenols, total triterpenoid acids, vitamin C, asiatic acid, quillaic acid, corosolic acid, and chlorogenic acid presented an overall upward trend. The content of maslinic acid showed a downward trend, whereas the content of neochlorogenic acid did not change much throughout the whole growth period. The content changes in the loquat leaves were affected by the light durations and temperature changes in different seasons, with mutual transit during the flowering and fruit growth processes. Sampling in May to June was found to be a most optimized option when applied in Chinese medicine processing; however, the degree of fibrosis is another indicator when it is used as food raw material. This study revealed the change pattern of major functional components of loquat leaves during the annual growth period and provides a theoretical basis for the reasonable harvesting period of loquat leaves as raw materials for processing different types of products.