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BACKGROUND: The use of indigenous selected starters in winemaking is gaining interest due to certain advantages for the sensory quality of the wine. The present work shows the results of a laboratory experiment in which the influence of selected indigenous yeasts on the colour characteristics of Pinot Noir was studied with the use of high hydroxycinnamate decarboxylase activity yeasts. Pichia guilliermondii ZIM624 and Wickerhamomyces anomalus S138 yeasts were used in sequential fermentation with two strains of Saccharomyces cerevisiae, the native ZIM2180 strain and commercial Fermol Premier Cru (FPC). RESULTS: In co‐inoculation fermentations, non‐Saccharomyces yeasts decreased colour intensity (on average by 25.5%). In wines fermented with ZIM624, the concentration of vinylphenolic pyranoanthocyanins increased (average concentration 1.5 mg L−1). However, vitisin concentration was significantly higher in S138 + FPC fermentation (1.3 mg L−1 and an average of 0.9 mg L−1, respectively). Pinot Noir wines fermented with only ZIM2180 and sequential inoculation of ZIM624 + ZIM2180 resulted in significantly higher colour intensity (6.1 ± 0.0 AU and 4.4 ± 0.0 AU, respectively) and lower wine hue parameters compared to other wines. Sensory evaluation also showed that both wines had the highest perceived colour intensity and purple colour suggesting improvement in wine quality parameters. CONCLUSIONS: The results confirmed that selected indigenous starters made out of Saccharomyces and non‐Saccharomyces yeasts can alter Pinot Noir wine colour parameters and improve wine colour properties. Those yeasts properties should be investigated prior to the development of new commercial starters but also be considered in large scale spontaneous fermentations of low colour intensity red wines like Pinot Noir. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Historically, yeasts from the genus Saccharomyces have been conventionally used in the production of wine and other fermented beverages. Traditionally, their main role has been the transformation of sugars into ethanol, however, research has shown that yeasts also influence wine aroma, texture, flavour and colour. In lieu of this, non-Saccharomyces yeasts, which have been considered as spoilage yeasts in the past, have been exploited as potential wine starters because they can improve the sensorial characteristics of wines. Because they are considered to be poor fermenters, mixed fermentations with Saccharomyces yeasts are applied either in a form of co-inoculation or sequential fermentation. Among wine characteristics, colour of red wines has special importance because it is the first wine characteristic perceived by the consumers. Red wine colour stems from anthocyanins, located in the grape skins that are extracted to grape must during maceration/fermentation. Various technological strategies in the winemaking process have already been employed to improve wine colour. One of them is yeast-mediated colour improvement employing a careful selection of yeast starters that can promote the synthesis of stable colour pigments pyranoanthocyanins from anthocyanins. The two most known groups of pyranoanthocyanins are vinylphenolic pyranoanthocyanins and vitisins. In comparison to anthocyanins they are less susceptible to pH, SO2 bleaching and oxygen presence. Their concentration in the wines differs according to the yeast strain used and the type of fermentation applied. Furthermore, wine colour can also be influenced by the cell wall adsorption capability of yeasts. Numerous studies have shown the positive influence of a careful selection of non-Saccharomyces yeast in promoting stable pigments synthesis in the production of wine. In this review, we discuss how application of different yeast species - Saccharomyces and non-Saccharomyces can enhance wine colour through different fermentation strategies applied. [ABSTRACT FROM AUTHOR]

Wine fermentation is a complex process driven by yeasts, which influence the key properties of wine quality: aroma, flavour and colour. We investigated 95 different Saccharomyces and non- Saccharomyces strains for their impact on wine colour through the synthesis of the stable pigments, pyranoanthocyanins. All strains were screened for their hydroxycinnamate decarboxylase (HCDC) activity that varied from 0.0% to 91.1%. Eight strains that showed more than 40% HCDC activity were further studied for vinylphenolic pyranoanthocyanin formation. Fermentations were carried out in deep well microtiter plates using synthetic grape must containing Pinot Noir skin extract supplemented with p -coumaric acid. Two strains Pichia guilliermondii ZIM624 and Wickerhamomyces anomalus S138 synthesized vinylphenolic pyranoanthocyanins in the highest concentration in single culture fermentations, 40.2 and 38.5 mg L−1, respectively. The highest produced concentration of vinylphenolic pyranoanthocyanins in co-inoculation experiments was 16.4 mg L−1 compared to 29.8 mg L−1 in sequential fermentations. For the first time, S. paradoxus strains were assessed for pyranoanthocyanin formation. Selected strains were also tested as mono-cultures for adsorption of anthocyanins on yeast cell walls and all strains showed anthocyanin and pyranoanthocyanin adsorption to their cell wall with Metschnikowia reukafii ZIM2019 showing the highest adsorbing capability (9.1%). • 95 yeasts strains characterized for hydroxycinnamate decarboxylase (HCDC) activity. • Sequential fermentation produced more pyranoanthocyanin than co-inoculation trials. • Yeasts adsorb anthocyanins and pyranoanthocyanins. • Vinylphenolic pyranoanthocyanin formation reported first time in three yeast species. [ABSTRACT FROM AUTHOR]