Comparison of Different Extraction Methods to Predict Anthocyanin Concentration and Color Characteristics of Red Wines

Stephan Sommer,Seth Cohen

doi:10.3390/fermentation4020039

Abstract

Red wines ferment in contact with skins to extract polyphenols and anthocyanins that help build, establish, and stabilize color. Concentration and composition vary among genera, species, and cultivars. For this study, 11 grapes representing Vitis vinifera (Cabernet Sauvignon, Merlot, Cabernet Franc, Barbera, Syrah, Petite Sirah, Mourvedre), Vitis labrusca (Concord), Muscadinia rotundifolia (Noble), and French-American hybrids (Marquette, Chambourcin) were selected. All cultivars were fermented on skins while color extraction was monitored daily. Each grape was also extracted using six different methods (microwave, and ultrasound assisted, Glorie procedure, ITV Standard (Institut Technique de la Vigne et du Vin), AWRI method (Australian Wine and Research Institute), solvent extraction of skins) and compared to color characteristics of the wines produced by fermentation. Results show that the extraction pattern varies among cultivars. Post-fermentation maceration, pressing, and sulfur dioxide addition lead to color loss up to 68 percent of the original maximum with the highest loss for native American grapes and hybrid varieties. Extraction procedures over-estimate color in the finished wine but are more accurate if compared to peak extraction levels during fermentation. Color loss and suitability of different extraction procedures to predict color characteristics of fermented wine strongly depend on the complexity of the anthocyanin spectrum and therefore the cultivar used.

Highlights

Red wines are usually fermented in contact with skins and seeds to extract polyphenols, including anthocyanins, that help to build and stabilize color
Extraction kinetics during fermentation are strongly dependent on cultivar, wine style, fermentation conditions, pH and degree of ripeness [4,7], which makes the prediction of color characteristics in the finished wine based on original grape composition very challenging
The results indicate that most extraction methods correlate significantly with the phenolic composition of the finished wines

Summary

Introduction

Red wines are usually fermented in contact with skins and seeds to extract polyphenols, including anthocyanins, that help to build and stabilize color. The chemical structure of anthocyanins is very variable and directly influences extractability, solubility, and color characteristics in juice and wine [3,4]. While most cultivars of Vitis vinifera have only simple anthocyanin glucosides and acylated derivatives [5], species like Vitis labrusca or other genera like Muscadinia rotundifolia, or hybrid grapes can display a wider range of anthocyanins including diglycosides of variable composition and structure [2,6]. Extraction kinetics during fermentation are strongly dependent on cultivar, wine style, fermentation conditions, pH and degree of ripeness [4,7], which makes the prediction of color characteristics in the finished wine based on original grape composition very challenging. Several polyphenol extraction approaches have been described in the literature that range from solvent based methods [9,10,11] to combinations between physical treatments

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Conclusion