Mineral Element Distribution in the Soil-Plant System of Dried Tangerine Peel and Geographical Origin Discrimination

This study investigated the distribution, enrichment, and transfer patterns of mineral elements in the soil-plant system of dried tangerine peel (Citrus reticulata ‘Chachi’, or Chenpi) from four production regions: Xinhui, Enping and Boluo in Guangdong Province, and Pubei in Guangxi Province, aiming to identify key element indicators with causal basis for geographical origin discrimination. Citrus reticulata ‘Chachi’ root, surrounding soil, leaf, and peel samples at different maturity stages (green, semi-ripe, and fully ripe) were collected simultaneously from these regions. The contents of 36 mineral elements were determined and systematically analyzed using enrichment factors and principal component analysis (PCA). The results showed that the contents of elements such as B, La, Ce, Pr, Nd, and Sm were significantly higher in the soil sample from Xinhui than in those from the other regions (P < 0.05). Among the four production regions, the leaf and peel samples from Xinhui exhibited the strongest enrichment capacity for Cu, Co, and V. The PCA results revealed the continuous enrichment of rare earth elements (Y, Er, Ho, Dy, etc.) in the soil-plant system of the Boluo region, constituting a key basis for the geographical origin discrimination of Chenpi. This study also found that green peels had the strongest correlation with soil elements, establishing them as sensitive materials for the geographical origin tracing of Chenpi. As fruit maturity increased, the elemental distribution stabilized, and the distribution patterns of macro elements such as K, P, and Ca could effectively discriminate among Xinhui, Enping, and Pubei Chenpi. This study has not only verified the feasibility of using mineral element fingerprinting for the geographical origin discrimination of dried tangerine peel, but has also elucidated the formation mechanism of discriminant indicators from the perspective of elemental migration and accumulation pathways, providing a theoretical basis and scientific evidence for constructing a robust geographical origin traceability system for dried tangerine peel.