Incorporation of Malvidin-3-Glucoside into High Molecular Weight Polyphenols during Fermentation and Wine Aging

Abstract

A decrease in anthocyanin concentration throughout the late stages of fermentation and aging has been well documented and is associated with the formation of polymeric pigments or pigmented tannins. In order to understand the formation of polymeric pigments, a ³H-labeled anthocyanin (malvidin-3-glucoside) was added to a fermenting juice and to a young wine. During fermentation, there was a rapid disappearance of tritium from solution 24 hr after the addition, suggesting that half of the anthocyanins were associated with grape solids. During the early stages of aging, there were negligible losses of radioactivity, with a steep decline in malvidin-3-glucoside. In the aging experiment, most of the anthocyanins appeared to incorporate into polymeric structures with negligible losses elsewhere. Furthermore, these polymers changed over time, altering their visible absorbance. Aging variables such as wine pH, additional tannin levels, and copigmentation had little or no effect. However, temperature had pronounced effects during polymer pigment formation.