Influence of Select Non-<i>Saccharomyces</i> Yeast on <i>Hanseniaspora uvarum</i> Growth during Prefermentation Cold Maceration

Abstract

This study investigated the effect of select non-<i>Saccharomyces</i> yeast strains on <i>Hanseniaspora uvarum</i> growth and acetic acid and ethyl acetate production during prefermentation cold soak. We tested commercially available non-<i>Saccharomyces</i> yeasts for their ability to reduce <i>H. uvarum</i> growth and acetic acid production during a simulated cold soak in a grape juice-based medium. All tested non-<i>Saccharomyces</i> yeast reduced <i>H. uvarum</i> growth and acetic acid production, with some yeast having a greater impact than others. Following the screening of non-<i>Saccharomyces</i> yeast, we tested 14 different <i>H. uvarum</i> isolates against a selected non-<i>Saccharomyces</i> yeast, <i>Metschnikowia fructicola</i>, and found that all <i>H. uvarum</i> isolates had reduced growth and acetic acid production when grown in co-culture with <i>M. fructicola</i>, with variation between isolates noted. Finally, we evaluated the effect of <i>M. fructicola</i> on <i>H. uvarum</i> during prefermentation cold soak of Pinot noir grapes. Pinot noir grapes were inoculated with a combination of <i>H. uvarum</i> and <i>M. fructicola</i> and cold soaked for six days at 8°C. At the end of cold soaking, treatments inoculated with <i>M. fructicola</i> contained lower populations of <i>H. uvarum</i> and significantly lower acetic acid and ethyl acetate concentrations compared with treatments not inoculated with <i>M. fructicola</i>. After the completion of alcoholic fermentation, wines where <i>M. fructicola</i> was added contained significantly lower ethyl acetate but no differences in acetic acid concentration. These results suggest that adding select non-<i>Saccharomyces</i> yeast may be another method to reduce the risk of spoilage by <i>H. uvarum</i> during prefermentation cold soaking.