Phenolic Copigment Enhanced Anthocyanin Stability and Color Intensity of Frozen Red Huajiao (Zanthoxylum bungeanum...

Anthocyanin stability substantially determines the postharvest storage quality of red Huajiao (Zanthoxylum bungeanum Maxim.). Herein, the composition of red Huajiao anthocyanins (RHAs) was characterized, and the copigmentation performance of seven phenolic compounds with RHAs was comparatively evaluated, together with verifying their practical efficacy in maintaining the overall quality of red Huajiao during frozen storage. UPLC-Q-TOF-MS/MS analysis identified ten anthocyanin monomers in RHAs, among which delphinidin-3,5-diglucoside (D3,5G, 28.23%), and delphinidin-3-O-glucoside (D3G, 14.86%) were verified as the predominant monomers. Naringin (NA) exhibited an optimal copigmentation effect, achieving a maximum color enhancement rate of 19.46% at a 1:40 molar ratio and a pH of 3.0 at 20 °C, while thermodynamic tests verified the excellent stability of the naringin-RHA complex. The copigmentation interactions between RHAs and copigments were largely attributed to hydrogen bonds, π-π stacking, and alkyl hydrophobic interactions. Considering practical application cost and flavor compatibility, chlorogenic acid (CGA) was selected as the preferred alternative copigment. Frozen storage tests suggested that soaking pretreatment with 10 mmol/L CGA effectively delayed color fading and maintained the integrity of the oil gland and the good sensory quality and color attributes of red Hujiao, with no adverse impacts on its inherent flavor and numbing components. Collectively, phenolic-mediated intermolecular copigmentation represents an efficient technical means for stabilizing color and maintaining the commercial quality of postharvest red Huajiao during frozen storage.