Study on the Material Basis of the "the Older, the Better" Phenomenon in Aurantii Fructus Using Fingerprinting Combined With Chemometric Analysis.

Aurantii Fructus (AF), the dried immature fruit of Citrus aurantium L., is a widely used qi-regulating herb in clinical practice. Traditional medical texts describe AF as "the older, the better," implying that aging moderates its medicinal properties and enhances efficacy, although the mechanisms remain unclear. Here, dynamic changes in volatile and nonvolatile components during AF aging were investigated using long-term natural aging and accelerated aging models, involving raw AF and four processed forms. Compositional variations across aging stages were characterized by high-performance liquid chromatography (HPLC), electronic nose analysis, and multivariate chemometrics. During long-term aging, flavonoid glycosides such as naringin gradually decreased and stabilized, whereas small-molecule flavonoids and polymethoxyflavonoids increased, likely due to microbial transformation. Compared with raw AF, processed products better preserved key active constituents during aging, indicating improved quality stability. Electronic nose results showed an overall decline in volatile components, particularly hydrocarbons such as D-limonene, supporting the traditional concept that aging reduces "dryness." However, high-temperature processing accelerated volatile loss, and accelerated aging caused more drastic compositional changes, potentially compromising quality. Overall, this study clarifies the chemical basis of the "the older, the better" concept of AF and provides scientific support for quality evaluation and aging process optimization.