PH: Difference between revisions

'''pH''' is a fundamental chemical parameter in wine, expressing the concentration of hydrogen ions and thereby the acidity–alkalinity balance of grape juice and finished wine. In oenology, pH is distinct from total (titratable) acidity and plays a critical role in microbial stability, colour expression, oxidation behaviour, and sensory perception.<ref>Robinson (ed.), ''The Oxford Companion to Wine'', Oxford University Press, 2015, ISBN 9780198705383.</ref>

pH strongly influences numerous chemical equilibria in wine. It affects the dissociation of organic acids, the solubility of potassium salts, and the redox behaviour of phenolic compounds. Lower pH generally slows oxidative reactions and increases the effectiveness of sulfur dioxide as an antioxidant and antimicrobial agent.<ref>Waterhouse, Sacks & Jeffery, ''Understanding Wine Chemistry'', Wiley, 2016, ISBN 9781118627808.</ref>

In red wines, pH has a major impact on colour stability. Anthocyanins are more stable and intensely coloured at lower pH, whereas higher pH values promote colour loss and browning over time.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Volume 2'', Wiley, 2006, ISBN 9780470010396.</ref>

Wine pH is one of the principal determinants of microbial risk. Lower pH environments inhibit the growth of spoilage organisms such as lactic acid bacteria and Brettanomyces, while higher pH wines require more careful management through sulfur dioxide, temperature control, and filtration.<ref>Boulton et al., ''Principles and Practices of Winemaking'', Springer, 1999, ISBN 9780834217011.</ref>

From a regulatory and technical standpoint, pH is therefore closely monitored during fermentation, maturation, and bottling.<ref>OIV, “Acidity and pH in wine”, https://www.oiv.int</ref>

Grape pH at harvest is shaped by variety, climate, soil, and vineyard practices. Warmer growing conditions tend to increase grape pH through accelerated malic acid degradation and potassium accumulation, while cooler climates favour lower pH values.<ref>Keller, ''The Science of Grapevines'', Academic Press, 2015, ISBN 9780124199873.</ref>

Climate change has been widely associated with rising grape and wine pH levels in many regions, prompting renewed focus on acid management in both vineyard and cellar.<ref>Jones et al., ''Climate Change and Global Wine Quality'', Wiley, 2012, ISBN 9781118450048.</ref>

Winemakers may influence pH through harvest timing, blending, acidification or deacidification, and choices affecting potassium extraction during fermentation and ageing. Such interventions are regulated and guided by international standards and best-practice recommendations.<ref>UC Davis, “Wine pH and quality”, https://wineserver.ucdavis.edu</ref><ref>AWRI, “Managing wine pH”, https://www.awri.com.au</ref>

The management of pH is closely linked to stylistic goals, market preferences, and regional norms, particularly in the context of globalised wine production.<ref>Anderson & Pinilla, ''Wine Globalization'', Cambridge University Press, 2018, ISBN 9781108445687.</ref>

Awareness of pH as a controlling parameter in winemaking developed alongside advances in analytical chemistry during the twentieth century. Earlier wine cultures relied on empirical assessments of acidity, whereas modern oenology integrates pH measurement into routine quality control.<ref>Unwin, ''Wine and the Vine'', Routledge, 1991, ISBN 9780415042698.</ref>

Contemporary understanding of pH now underpins both technical winemaking decisions and broader discussions of wine style, stability, and ageing potential.<ref>FAO, “Grape composition”, https://www.fao.org</ref>