High yield production of cyanidin-derived pyranoanthocyanins using 4-vinylphenol and 4-vinylguaiacol as cofactors.

Pyranoanthocyanins are anthocyanin-derived pigments with vivid colors and enhanced stability, making them promising food colorants. We evaluated two 4-vinylphenols, decarboxylated p-coumaric (pCA) and ferulic acid (FA), as cofactors for pyranoanthocyanin formation. Cyanidin-3-glycosides from saponified black carrot were incubated with 4-vinylphenol or 4-vinylguaiacol in different anthocyanin-to-cofactor molar ratios (1:1-1:30) to form pyranoanthocyanins. Formation efficiency (45 °C, ≤96 h) was compared to their respective precursors at a 1:30 ratio. Composition changes were monitored using uHPLC-PDA-ESI-MS/MS. Pyranoanthocyanin yields with 4-vinylphenol (13.8-33.4%) were ∼12× higher than with pCA and yields with 4-vinylguaiacol (8.1-31.0%) were ∼6.5× higher than with FA. Molar ratios of 1:5 and 1:10 yielded significantly more pyranoanthocyanins. Pyranoanthocyanin formation with 4-vinylphenols followed first-order kinetics, whereas formation with hydroxycinnamic acids followed zero-order kinetics. Detection of intermediate compounds was consistent with a nucleophilic addition and aromatization formation mechanism. Overall, pyranoanthocyanin formation with 4-vinylphenols was more efficient than with hydroxycinnamic acids.