Discovering the Influence of Microorganisms on Wine Color

Abstract

Flavor, composition and quality of wine are influenced by microorganisms present on the grapevine surface which are transferred to the must during vinification. The microbiota is highly variable with a prevalence of non-Saccharomyces yeasts, whereas Saccharomyces cerevisiae is present at low number. For wine production an essential step is the fermentation carried out by different starter cultures of S. cerevisiae alone or in mixed fermentation with non-Saccharomyces species that produce wines with significant differences in chemical composition. During vinification wine color can be influenced by yeasts interacting with anthocyanin. Yeasts can influence wine phenolic composition in different manners: direct interactions—cell wall adsorption or enzyme activities—and/or indirectly—production of primary and secondary metabolites and fermentation products. Some of these characteristics are heritable trait in yeast and/or can be strain dependent. For this reason, the stability, aroma, and color of wines depend on strain/strains used during must fermentation. Saccharomyces cerevisiae or non-Saccharomyces can produce metabolites reacting with anthocyanins and favor the formation of vitisin A and B type pyranoanthocyanins, contributing to color stability. In addition, yeasts affect the intensity and tonality of wine color by the action of β-glycosidase on anthocyanins or anthocyanidase enzymes or by the pigments adsorption on the yeast cell wall. These activities are strain dependent and are characterized by a great inter-species variability. Therefore, they should be considered a target for yeast strain selection and considered during the development of tailored mixed fermentations to improve wine production. In addition, some lactic acid bacteria seem to influence the color of red wines affecting anthocyanins’ profile. In fact, the increase of the pH or the ability to degrade pyruvic acid and acetaldehyde, as well as anthocyanin adsorption by bacterial cells are responsible for color loss during malolactic fermentation. Lactic acid bacteria show different adsorption capacity probably because of the variable composition of the cell walls. The aim of this review is to offer a critical overview of the roles played by wine microorganisms in the definition of intensity and tonality of wines’ color.

Effects of Phenolic Evolution on Color Characteristics of Single-Cultivar Vitis vinifera L. Marselan and Merlot Wines during Vinification and Aging

“…Previous studies have shown that the concentrations of Vitisins peak at the post-fermentation and early-aging stages, with Vitisin B levels being slightly lower than those of Vitisin A [41]. The color loss in wine following malolactic fermentation may be caused by several factors, such as the increase in pH during this process, the reduced ability of bacteria to produce pyruvate and acetaldehyde, and the adsorption of anthocyanins by bacterial cells [36]. The previous study also showed that malolactic fermentation resulted in lower levels of polymeric pigments and Vitisin A and B, and higher levels of grape-derived anthocyanins compared to wine without malolactic fermentation [36].…”

“…This decrease may be caused by various factors, such as the adsorption of yeast distillers' grains, enzymatic hydrolysis, oxidation, or the formation of copolymers from other nonanthocyanin phenols. These processes occur from the latter phase of alcoholic fermentation to the stage of malolactic fermentation and bottle storage [36]. Previous research has demonstrated that during this phase, anthocyanins combine with tannins or react with hydroxycinnamate to form more stable polymeric pigments [37,38].…”

“…The color loss in wine following malolactic fermentation may be caused by several factors, such as the increase in pH during this process, the reduced ability of bacteria to produce pyruvate and acetaldehyde, and the adsorption of anthocyanins by bacterial cells [36]. The previous study also showed that malolactic fermentation resulted in lower levels of polymeric pigments and Vitisin A and B, and higher levels of grape-derived anthocyanins compared to wine without malolactic fermentation [36]. Pinotin has spectral characteristics similar to Vitisin, with a shift in the maximum absorption wavelength towards shorter wavelengths, indicating an orange-red hue [33].…”

Torulaspora delbrueckii Improves Organoleptic Properties and Promotes Malolactic Fermentation in Carbonic Maceration Wines

“…This reduction could be attributed to the formation of aglycones from anthocyanins, which are susceptible to oxidation [40], or it could be due to the high β-glucosidase activity of certain T. delbrueckii strains [41]. Additionally, it could be related to the absorption of pigments by the yeast walls, which has been shown to vary depending on the yeast species or strain [42,43].…”

Enhanced mass transfer of pulsed vacuum pressure pickling and changes in quality of sour bamboo shoots

“…After removing the maximum and minimum values, the mean value of the remaining data was obtained and used for calculation. Total color difference (E * ) was obtained through the following equation (Dai et al, 2020;Deng et al, 2020;Tofalo et al, 2021):…”