Evaluation of the potential of Metschnikowia pulcherrima to reduce SO2 in winemaking: impact on wine phenolic compounds and their bottle evolution

Abstract

Due to its antimicrobial and antioxidant activities, the use of SO₂ has been of great importance in enology. However, its use has been linked to the generation of non-communicable diseases, and delayed malolactic fermentation (MLF), leading to wine discolouration. Adding non-Saccharomyces yeasts has been proposed as an alternative to improve wines’ sensory and nutritional characteristics. In this sense, this work aimed to use Metschnikowia pulcherrima as a wine colour enhancer, mainly analysing Tempranillo red wine’s phenolic composition. Four assays were conducted in duplicate, comparing sequential fermentations with SO₂ and/or non-Saccharomyces and Saccharomyces yeast as starter, using M. pulcherrima concentrations of 10 and 50 g/hL. Analyses were performed at the end of MLF, 6 and 9 months of wine ageing in bottles. Phenolic compounds in wines, including anthocyanins and non-anthocyanins, were analysed by HPLC–DAD. A slight increase was observed in most phenolic families in co-fermentations with mixed cultures after 9 months of bottling, suggesting the potential of M. pulcherrima as an initiator to enhance the sensory profile and act as a stabilizing agent in wines, potentially replacing SO₂. Overall, the results indicated that the selection of non-Saccharomyces yeasts has a great impact on the wine quality, mainly on the composition of anthocyanins, flavonols and flavanols. In this sense, the use of M. pulcherrima as fermentation starters could be of great interest to achieve iniquitous, stable and better-coloured wines.