Effect of co‐inoculation with yeast and bacteria on chemical and sensory characteristics of commercial Cabernet Franc red wine from Switzerland

Abstract BACKGROUND Malolactic fermentation (MLF) is a critical step in modern winemaking and the co‐inoculation of lactic acid bacteria with yeasts represents an emerging approach to improve the quality of wine. This study aims to evaluate the effect of inoculation timing on the chemical and sensory characteristics of two commercial Cabernet Franc wines: (i) a control wine in which MLF was inoculated after the completion of alcoholic fermentation (AF); and (ii) a co‐inoculated wine where simultaneous alcoholic and malolactic fermentations occurred. RESULTS Besides the expected full conversion of malic acid into lactic acid, the MLF with co‐inoculum of yeast/bacteria at initial AF allowed for reduced fermentation times, i.e. faster winemaking process. Although important changes in the chemical parameters of wines were found, especially color intensity and volatile compounds, there was a trend on the sensory evaluation of wines with a greater perception of red and ripe fruits in the case of co‐inoculation wine, while the control wine was dominated by notes of spice and herbs. The results of GC/MS analysis showed the largest differences for the 3‐hydroxy‐2‐butanone (acetoin, the reduced form of diacetyl) and isoamyl alcohol concentrations, the former was 3.2 times higher under co‐inoculum conditions, whereas the latter showed the opposite behavior. CONCLUSION The co‐inoculation protocol proposed is a valuable choice for innovative winemaking of Cabernet Franc wines, and results from a large‐scale winemaking process are provided for the first time. © 2015 Society of Chemical Industry