Stability of copigmented anthocyanins and ascorbic acid in a grape juice model system

Area of Science:

• Food Science
• Plant Biochemistry
• Color Chemistry

Background:

• Anthocyanins from Vitis vinifera contribute red color to beverages but are prone to degradation.
• Ascorbic acid is often added to juices but can accelerate pigment loss.
• Polyphenolic cofactors are explored for their potential to stabilize anthocyanins.

Purpose of the Study:

• To evaluate rosemary polyphenolic cofactors as stabilizing agents for red grape anthocyanins.
• To assess the impact of cofactors on anthocyanin and ascorbic acid stability during storage.
• To determine the effect of copigmentation on color intensity and vitamin retention in a model juice system.

Main Methods:

• Red grape anthocyanins were studied in a model juice system under normal (25°C) and accelerated (35°C) storage conditions.
• Rosemary polyphenolic cofactors were added at varying concentrations (0, 0.2, 0.4% v/v).
• Degradation kinetics of anthocyanins and ascorbic acid were analyzed, and colorimetric properties were measured.

Main Results:

• Cofactor addition caused concentration-dependent hyperchromic and bathochromic shifts, enhancing red color intensity.
• Copigmented systems showed reduced L-ascorbic acid conversion to dehydroascorbic acid, improving vitamin retention.
• Copigmentation helped retain higher anthocyanin content in the presence of ascorbic acid compared to controls.

Conclusions:

• Rosemary polyphenolic cofactors effectively stabilize red grape anthocyanins and enhance color.
• Copigmentation reduces degradation of both pigments and ascorbic acid, improving product quality.
• Cofactors offer a strategy to mask undesirable color changes and extend shelf life in anthocyanin-rich products.