South Africa Wine Technical Yearbook 2025

prevalent (Gobbi et al ., 2022). These organisms play vital roles in nutrient cycling and help vines absorb essential minerals. By fostering healthy microbial communities, winemakers can enhance grape development and, ultimately, wine quality. In some cases, beneficial microbes can even protect vines from pests and diseases, offering a natural form of pest control (Nerva et al ., 2021). During fermentation, specific microbes – particularly yeasts like Saccharomyces cerevisiae – are essential for converting grape sugars into alcohol. This process also produces secondary metabolites that significantly influence wine flavour and aroma. While some researchers argue that microbes have little direct influence on grape chemistry, their role in fermentation is undeniable (Gilbert et al ., 2014). Microbes have been identified as an important component of the ultimate sensorial properties of wines through fermentation. The impact of microbes on wine fermentation, especially lactic acid bacteria and yeasts, has led to the creation of commercial products which can be used during alcoholic fermentation (Gilbert et al ., 2014:5). All ecological interactions that take place between the microbiota, the plant and the environment play an important role in the outcome of wine fermentation (García-Izquierdo et al ., 2024). Fungi can profoundly influence the phenotype of wine by impacting the health and development of grapevines and berries, thereby affecting quality. Additionally, they control wine flavour, aroma and style through their roles in the fermentation process. During this process, Saccharomyces cerevisiae – the main yeast used for alcohol fermentation – converts sugars into ethanol and generates a range of secondary metabolites, including volatile compounds, that significantly influence the wine flavour and aroma (Knight et al ., 2015:2). Integrating microbial ecology into agriculture could revolutionise site selection and management by using probiotics to introduce beneficial bacteria that improve soil quality and increase crop yields Gilbert et al ., (2014). Additionally, this method can improve wine terroir or even reproduce those favourable terroirs in areas unsuitable for producing wine with such properties (Gilbert et al ., 2014). Microbes are complex species, according to Knight and other authors, and are often unpredictable, which makes their chemical and sensorial properties difficult to control experimentally. Gilbert and other authors argue that bacteria and fungi only play a role in the fermentation process and have little direct influence on grape chemistry. Alexandre (2020:1) also argues that while the microbial community of a vineyard is dependent on geographic location, there is no strong evidence that microbes contribute to the so-called “terroir effect”. The microbial terroir of wine grapes plays a crucial role

in winemaking, affecting both vine health and the quality of the wine produced. By gaining a better understanding and managing the microbial communities in their vineyards, viticulturists and winemakers can improve vine health and shape the distinctive qualities of their wines. However, more thorough research needs to be done as the concept of microbial terroir is still the subject of intense debate (Alexandre, 2020). The future of terroir and microbial management The emerging understanding of microbial terroir opens new possibilities for viticulture. By managing and even introducing beneficial microorganisms into vineyard soils, winemakers may be able to enhance the expression of terroir and produce wines with distinct, desirable characteristics (Gilbert et al ., 2014). While some debate continues regarding the extent of microbial influence, particularly regarding grape chemistry (Alexandre, 2020), it is clear that microbes are an essential factor in the complex interactions that define terroir. Conclusion – terroir as a dynamic concept Though often tied to tradition, terroir is not static. It evolves with new knowledge, techniques and even climate change. As winemakers experiment with different approaches, terroir will continue to be a focal point in the ever-changing world of wine. Whether you’re sipping a bold red from Bordeaux or a crisp white from the Loire Valley, you’re tasting not just the grape, but the unique blend of earth, weather and human expertise that makes each bottle of wine truly one of a kind. In the world of wine, terroir is everything, and soil is one of its most crucial components. From regulating vine temperature to providing essential nutrients, soil plays a key role in shaping the character of the wine. As research continues to shed light on the impact of soil on grape quality, it becomes clear that this hidden factor holds the key to understanding the complexities of terroir. Whether you’re enjoying a bold red from Valpolicella or a crisp Albariño from Spain, remember that it’s the soil beneath the vines that helps make each bottle truly unique. In conclusion, terroir is a multifaceted concept that encompasses soil, climate and microbial life, all of which influence grape quality and wine production. By understanding and managing these factors, winemakers can harness the unique characteristics of their vineyards to produce wines that truly reflect their place of origin. As research into microbial communities continues to evolve, it may revolutionise how we think about terroir and winemaking, leading to even greater innovations in wine production. 

For more information, contact Anton Nel at nelap@cput.co.za. Reference https://wineland.co.za/the-fascinating-world-of-terroir-in-winemaking-part-2/

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TECHNICAL YEARBOOK 2025