Enhancement of color stability of cyanidin-3-O-glucoside by copigmentation with punicalagin: multispectral analysis
Yijin Peng1, Wenhui Zou1, Qisheng Yue1
1Faculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan Province 650500, China; Yunnan Engineering Research Center for Fruit & Vegetable Products, Kunming, Yunnan Province 650500, China; International Green Food Processing Research and Development Center of Kunming City, Kunming, Yunnan Province 650500, China; Yunnan Key Laboratory for Food Advanced Manufacturing, Kunming, Yunnan Province 650500, China.
Abstract:
This study investigated the copigmentation mechanism between punicalagin (PUN) and cyanidin-3-O-glucoside (C3G) using spectroscopic analysis, thermodynamic evaluation, and quantum chemical modeling. UV-VIS spectra revealed enhanced absorbance and red shifts upon increasing PUN concentration to the C3G solution, indicating intensified color. Copigmentation was most effective at acidic pH (3-6) and declined at higher temperatures. Thermodynamic parameters indicated a spontaneous, exothermic interaction between PUN and C3G, involving hydrogen bonding and π-π stacking. FT-IR, 1H NMR, and IGMH analyses confirmed these interactions and revealed that α-PUN formed more stable complexes with C3G than β-PUN, due to cooperative aromatic-polar interactions and more favorable stacking geometry. Quantum calculations supported the greater stability of α-C3G/PUN complexes. Furthermore, PUN significantly improved the thermal, light, and storage stability of C3G. These findings provide molecular-level insights into anthocyanin-ellagitannin copigmentation and demonstrate the potential of PUN as a natural copigment for improving color stability in food systems.
