The Impact of Fermenter Shape on the Performance of White Wine Alcoholic Fermentation and the Composition of the Resulting Wines in Laboratory-Scale Trials.

A great variety of vessels, including tanks with different shapes and made with different materials, have been installed in wineries during the last decade. However, the influence of the vessel shape itself during alcoholic fermentation and finished wine composition has not been assessed. In the present study, four different shaped borosilicate flasks (cylindrical, conical, ovoid, and spherical) were used to perform alcoholic fermentation of white grape juice in triplicate, following two different inoculation procedures: monoinoculation with a Saccharomyces cerevisiae commercial strain and sequential inoculation with Metschnikowia pulcherrima and Saccharomyces cerevisiae commercial strains. The shape of the fermenter impacted alcoholic fermentation performance and the composition of the resulting wines, although the influence of fermenter shape depended on the inoculation protocol. For example, flasks with hemispheric bottoms differed from those with flat bottoms in fermentation rate, yeast population, and dissolved oxygen throughout monoinoculated fermentation. In contrast, for the sequentially inoculated fermentations, the wines from the cylindrical flasks had the lowest contents of soluble polysaccharides (around 28% less) and volatile compounds (around 43% less). These results highlight the importance of the shape of fermenters, which should be considered a non-negligible factor in laboratory-scale trials as well as for winemaking at an industrial level. PRACTICAL APPLICATION: The present study can help winemakers to better understand the influence of employing vats and vessels with different shapes (such as the fashionable egg-shaped tanks) during alcoholic fermentation to produce white wines. Moreover, the presented results point to the relevance of the shape of fermentation flasks at laboratory scale to perform fermentative trials, given that the shape of the fermenter flask impacted the volatile composition and polysaccharides profile of the resulting wines.