One-day pyranoanthocyanin production: More efficient synthesis of anthocyanin-derived pigments using 4-vinylphenol
Mentor: M. Monica Giusti, Food Science and Technology
Anthocyanins are dietary flavonoids with vivid colors found in plant tissues. Anthocyanin-rich extracts can be used as food colorants substituting synthetic ones. Health concerns associated with the consumption of artificial colorants and an increased consumer awareness have accelerated the transition towards colorants from natural sources. However, problems arise in the application of anthocyanins as food colorants due to their lack of stability. Pyranoanthocyanins (PACNs) are anthocyanin-derived pigments that bear a pyran ring in their structure, with enhanced stability. Hydroxyphenyl–PACNs (HP-PACNs) are a class of pigments found in wine resulting from the cycloaddition between hydroxycinnamic acids and anthocyanins. Nonetheless, their synthesis is time-consuming, restricting their use by the industry. However, the production of HP-PACNs with 4-vinylphenols, decarboxylated hydroxycinnamic acids, may be faster. The objectives of this study were to determine the most efficient anthocyanin to 4-vinylphenol ratio for production of HP-PACNs, and to evaluate if a similar or lower 4-vinylphenol concentration was more efficient than p-coumaric acid. Saponified anthocyanins from black carrot were dissolved in pH 3.1 acidified water and mixed with 4-vinylphenol in molar ratios of 1:1, 1:5, 1:10, 1:20, and 1:30. A positive control of anthocyanins with p-coumaric acid was prepared for a final molar ratio of 1:30. Pyranoanthocyanin formation was evaluated after incubation at 45°C for 24 hours using HPLC-PDA analyses. PACN yield (%) and remaining pigment were calculated. PACN production with 4-vinylphenol was at least 34 times greater than with p-coumaric acid (p<0.05). Moreover, PACN yield with 4-vinylphenol at a molar ratio of 1:5 (36.3%), 1:10 (39.1%) and 1:20 (34.7%) was significantly higher than with 1:1 (14.0%) and 1:30 (28.7%). 4-Vinylphenol in a ratio of 1:5 and 1:10 had higher content of pigment remaining (39.7% and 40.2%, respectively) than the anthocyanin without cofactor (22.4%), but lower than the p-coumaric acid control (45.4%). Overall, synthesis of pyranoanthocyanins using 4-vinylphenols was faster than with p-coumaric acid, yielding higher amounts of pigment and requiring less cofactor. Future studies will focus on evaluating different temperatures and pH to further optimize pyranoanthocyanin synthesis. Ultimately, this will facilitate the transition from synthetic colorants to healthier alternatives from natural sources in the food industry.
what a neat study, great job steven!
Thank you very much, Ellia!