Comparison of chemical profiles and identification of key bioactive compound in yuzu (Citrus junos) pulp and peel

Yuzu (Citrus junos) is a popular citrus fruit known for its nutritional properties and rich content of various bioactive compounds. This study aimed to identify the chemical components in Yuzu peel and pulp and to investigate their key bioactive components and potential applications using several methods, including liquid chromatography, gas chromatography, network database screening, molecular docking simulation, molecular dynamics analysis, prokaryotic expression and surface plasmon resonance. Comparatively, Yuzu peel exhibited higher levels of most nutrients, especially K, Ca, and dietary fiber, while Yuzu pulp contained higher contents of protein and V_C. Subsequently, an in vitro digestion of Yuzu peel and pulp was performed, revealing the significant correlations (P < 0.05, R² 0.69-0.84) between antioxidant activity and flavonoid contents. Also, significant differences (P < 0.05) were observed in volatile and non-volatile components between Yuzu peel and pulp. Notably, Yuzu peel had higher flavonoid contents, especially for naringin and narirutin, whereas Yuzu pulp had higher organic acid contents, particularly citric acid. Yuzu flavonoids exhibited desirable antioxidant potential. Hesperidin may be the key bioactive component in Yuzu, with KEAP1 inferred to be its key target. The hesperidin-KEAP1 complexes displayed a strong binding energy of -12.2 kcal/mol and a KD value of 2.40 × 10^-9. The stable binding of complexes could reveal a potential antioxidant mechanism of Yuzu. In this study, the component and antioxidant potential of the Yuzu peel and pulp were highlighted and revealed. Taken together, our findings could support their high-value utilization in functional food products.