Non-Saccharomyces yeast and lactic acid bacteria in Co-inoculated fermentations with two Saccharomyces cerevisiae yeast strains: A strategy to improve the phenolic content of Syrah wine

Syrah must was co-inoculated with mixed cultures of Saccharomyces + O. oeni/Lb. plantarum and Saccharomyces + non-Saccharomyces + O. oeni/Lb. plantarum to evaluate the effect on phenolics and sensory attributes. Reference wines were produced by S. cerevisiae. Malvidin-3-O-glucoside, flavan-3-ols, flavonols and phenolic acids were quantified using a RP-HPLC technique. Physicochemical characteristics and sensory attributes were measured. Total acidity and alcohol in mixed co-inoculations were different from reference wines. The concentration of l-malic acid was 7-times less in mixed co-inoculations. Mixed co-inoculations had ca. 1.3-times more malvidin-3-O-glucoside and phenolic acids than reference wines. Flavan-3-ols and flavonols were not different between mixed co-inoculations and reference wines. Acidity and astringency were least in mixed co-inoculations. Mouthfeel and bitterness least in S. cerevisiae wines. Tasters preferred mixed co-inoculated wines. Mixed co-inoculation is a strategy to contemplate for Syrah vinification but the modalities of inoculation need further investigation. Success depends on a suitable combination of yeast/bacteria and consideration of strain variation.