South Africa Wine Technical Yearbook 2025

FIGURE 2. Principal component analysis (PCA) biplot of sensory data: The closer a descriptor is to a wine, the more strongly it contributes to that wine’s profile. [Data from a coded, randomised evaluation by nine experts (TASTEL WEB)].

Significance of this information for winemakers Maintaining freshness in wines is becoming increasingly challenging; however, specific yeast starters can help address this issue. This study highlights the potential of new malic acid-enhancing S. cerevisiae strains, ZYMAFLORE™ XAROM and KLIMA, to manage wine acidity and style. These can be combined with L. thermotolerans OMEGA to further boost this effect through lactic acid production, especially when used in sequential inoculation with S. cerevisiae. In red wines, the contribution of citric acid-preserving O. oeni strains like LACTOENOS™ BERRY Direct , which can favour freshness and fruit character, is of additional importance. Together, these starters represent valuable tools in the winemaker’s toolkit for preserving the freshness, balance and stability of wines. Looking ahead LAFFORT ® continues to explore novel yeasts and bacteria that can further stabilise acidity and freshness under increasingly variable climate conditions. Such developments will broaden the winemaker’s toolkit for both red and white wines, ensuring consistency and quality across vintages. 

In addition to malic acid, glycerol is another compound produced from sugars that can contribute to lower ethanol content in novel malic acid-producing S. cerevisiae strains. Accordingly, glycerol levels were markedly higher in both XAROM and KLIMA wines compared to FX10 (Figure 1E). Elevated glycerol production was maintained in OMEGA + KLIMA co-inoculations, which, like KLIMA alone, also exhibited particularly low acetic acid concentrations (Figure 1F). What about the sensory profiles of the wines? Unsurprisingly, upon fermentation, the young wines significantly differed in the number of sensory attributes (data not shown). To determine whether these differences persisted over time, the 2023 wines were re-tasted at 16 months of age. The results confirmed that each wine retained its distinct sensory profile (Figure 2). The FX10 control wine was associated with greater mouthfeel and overall impression; however, its high pH (4.0) without acidification makes microbial stabilisation challenging. Even after 16 months, XAROM was described as intense, with abundant red fruit and fermentative character, and was considered ‘ready to drink’. In contrast, KLIMA and OMEGA + KLIMA were perceived as having greater ageing potential, supported by more pronounced acidity and tannin structure, along with herbal, spicy and dark-fruit notes.

For more information, contact Morné Kemp at morne.kemp@laffort.com. Reference https://www.wineland.co.za/yeast-derived-acidification-of-red-wines/

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TECHNICAL YEARBOOK 2025