WINETECH Technical Yearbook 2021

although it may have similar results with a limited risk. Themain threat of spontaneous fermentation is that the style of the resulting wine is not according to expectations, does not comply with personal advantages or can even be spoiled. This implies that the grapes were not utilised correctly and can also have financial consequences. A wrong perception is that spontaneous fermentations need not be managed. As with inoculated fermentations, it must be monitored and controlled. Winemakers have the same aids like pump overs, temperature adjustments and wood maturation to make the necessary adjustments (Wright, 2021). REFERENCE Wright, C., 2021. A SWOT analysis of going wild. Wine BusinessMonthly , June 2021: 32-36.

terroir driven, because it can cause more unique environmental characteristics. It is alsomuch cheaper than inoculated fermenta- tions. Different genera have different volatile components resulting in a more complex flavour profile. Its structure advantages are mainly as result of the higher glycerol concentrations that are formed, and these characteristics are also incorporated in the development of commercial strains. Seeing that it is known that the yeast flora differs between vineyards, it can exhibit more pronounced differences between wines. The potential weak points of spontaneous fermentations are the following: the longer lag phase before fermentation commences, a lower yeast kinetics, especially at the end of fermentation, potential microbial spoilage, oxidation, stuck fermentation, unpredict- ability, differences between vintages and, longer tank engagement. It is consequently

essential that only sound grapes, with a low micro-population are considered for spon- taneous fermentation. Grapes with a high sugar concentration must rather also be avoided, because it is one of the reasons for sluggish or stuck fermentations. As a result of the proven fermentation characteristics, the resistance against lower temperatures and sulphur dioxide and the limited potential of off-flavours with Saccharomyces cerevi­ siae , the use of spontaneous fermentation is considerably riskier. Spontaneous fermentation can however offer marketing opportunities to wine. Yeast, which is native to vineyards, creates a home to it, which can be used to promote the distinctive characteristics of wine of specific vineyards. Consumers are increasingly interested to know more about the origin of purchased products, as well as which

additives are used during production. This is actually the reason for the interest in and growth of the “natural” wine movement. As a result of the unique characteristics of spontaneous fermented wines, winemakers havemore blending possibilities. Spontaneous fermentations can be used together with Saccharomyces inoculations where the fermentations are initiated by the wild yeasts followed by Saccharomyces inoculations to ensure that the fermentation is fluent and will be completed. A new concept is where species of so-called wild yeasts are commercially available to be used as co- inoculants together with Saccharomyces cerevisiae strains. It is especially strains of Saccharomyces uvarum , Hanseniaspora uvarum , Torulaspora delbrueckii and Kluyveromyces thermotolerans that are used. It is however doubtful whether it can be interpreted as spontaneous fermentation,

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