Anthocyanin degradation in oxidising grape musts

Abstract

White musts with added grape anthocyanis were prepared and oxidised using known amounts of oxygen. Although malvidin and peonidin glucosides were degraded at a slower rate than o-diphenolic anthocyanins, important losses of all pigments occurred in oxidising grape musts. Degradation was inhibited by glutathione in excess, meaning that enzymically generated quinones of caffeoyltartaric acid were involved in the degradation mechanisms. Addition of anthocyanins hardly modified the kinetics of caffeoyltartaric acid oxidation and conversion to 2-S-glutathionyl caffeoyltartaric acid (grape reaction product). All musts browned considerably during oxidation. Browning of white musts was measured as an increase of redness (a*) and a decrease of lightness (L*) and yellowness (6* and hue angle) whereas browning in anthocyanin added musts appeared essentially as a loss of red colour (a*).

Mechanism of Browning in Fresh Highbush Blueberry Fruit (Vaccinium corymbosum L). Role of Blueberry Polyphenol Oxidase, Chlorogenic Acid and Anthocyanins

“…However, no degradation occurred when enzymatic extract was inactivated by heating and chlorogenic acid was also not oxidised. The quinone formed from chlorogenic acid stimulated the anthocyanin degradation (Raynal and Moutounet 1989 ;Cheynier et al 1994). Anthocyanins with o-diphenolic B ring were oxidised via the enzymatically generated oquinone by coupled oxidation mechanism, whereas non-o-diphenolic anthocyanins formed adducts with the same o-quinone (Sarni et al 1995).…”

An Intracellular Laccase is Responsible for the Epicatechin Mediated Anthocyanin Degradation in Litchi Fruit Pericarp

“…These studies are based on the knowledge accumulated from pigment loss in fruit juices and wines (Cheynier et al, 1994;Kader et al, 1998). Polyphenol oxidases (PPOs) and peroxidase (POD) are the main enzymes that oxidize anthocyanins in fruit extracts, leading to the decrease in pigment content (Sarni et al, 1995;Kader et al, 1998).…”

Phytochemical profiling of phytoconstituents of grape, Jatropha curcas and Neem (Azadirachta indica) extracts

“…This could be due to browning process. The enzymatic oxidation of polyphenols, particularly, flavonoids, occurs during storage when cell integrity is affected (Cheynier, 2005(Cheynier, , 1994. Flavonoids, particularly, ortho-diphenols, can be oxidized to their corresponding semiquinones and quinones by oxidases such as polyphenol oxidase and peroxidases (Yoruk and Marshall, 2003;Walker and Ferrar, 1998).…”