Effect of genuine non-anthocyanin phenolics and chlorogenic acid on color and stability of black carrot (Daucus carota ssp. sativus var. atrorubens Alef.) anthocyanins

• Color intensity and thermal stability of black carrot anthocyanins were studied.
• Anthocyanins were combined with plant extracts and chlorogenic acid as co-pigments.
• Chlorogenic acid addition particularly enhanced stability of acylated anthocyanins.
• A green coffee bean extract enabled effective food-grade applications.

This work aimed at studying the color intensity and stability of black carrot anthocyanins as influenced by intermolecular co-pigmentation. For this purpose, purified anthocyanin solutions were supplemented with purified genuine black carrot phenolics, chlorogenic acid, and an aqueous phenolic-rich green coffee bean extract at various anthocyanin:co-pigment ratios (1:0–1:162; pH 3.6). The hyperchromic co-pigmentation effect depended on the concentration of added co-pigments, resulting in an absorbance increase of up to 22% at the absorption maximum. Anthocyanin stability during heating (90 °C, 5 h) was barely improved unless the concentrations of co-pigments exceeded those of their natural source. When adding co-pigments at ratios above 1:9.4, anthocyanin heat stability was significantly improved. As acylated anthocyanins were most stable, breeders might aim at increasing their content in the future, while breeding for high levels of colorless polyphenols may be unreachable. Nevertheless, we provided proof-of-concept for the successful color enhancement by the addition of a phenolic-rich green coffee bean extract, being useful for food-grade applications.

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