PH
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.[1]
Definition and measurement
pH is measured on a logarithmic scale, typically ranging in wine from approximately 2.8 to 4.0. Lower pH values indicate higher acidity and greater hydrogen ion concentration. Measurement is performed using a calibrated pH meter rather than by titration, which is used for determining total acidity.[2]
Although pH and total acidity are related, they describe different aspects of wine chemistry. Wines with similar total acidity may have different pH values depending on acid composition, potassium levels, and buffering capacity.[3]
Chemical significance
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.[4]
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.[5]
Microbial stability
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.[6]
From a regulatory and technical standpoint, pH is therefore closely monitored during fermentation, maturation, and bottling.[7]
Sensory perception
Although pH itself is not directly tasted, it influences how acidity is perceived. Wines with lower pH tend to taste fresher and more vibrant, while higher pH wines may appear softer, broader, or flatter, even at similar total acidity levels.[8]
pH also affects aromatic expression, particularly through its interaction with oxidation, ester stability, and volatile acidity perception.[9]
Viticultural factors
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.[10]
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.[11]
Winemaking control
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.[12][13]
The management of pH is closely linked to stylistic goals, market preferences, and regional norms, particularly in the context of globalised wine production.[14]
Historical and contextual perspective
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.[15]
Contemporary understanding of pH now underpins both technical winemaking decisions and broader discussions of wine style, stability, and ageing potential.[16]
See also
References
- ↑ Jancis Robinson, Oxford Companion to Wine, Oxford University Press, 17 Sept. 2015. ISBN 9780198705383.
- ↑ PhD Jackson, Ronald S., Wine Science: Principles and Applications, Academic Press Inc, 14 April 2020. ISBN 9780128161180.
- ↑ Pascal Ribéreau-Gayon, Yves Glories, Alain Maujean, Denis Dubourdieu, & 1 more, Handbook of Enology, Volume 2: The Chemistry of Wine - Stabilization and Treatments, Wiley, 31 Mar. 2006. ISBN 9780470010372.
- ↑ Andrew L. Waterhouse, Understanding Wine Chemistry, Wiley, 19 Aug. 2016. ISBN 9781118627808.
- ↑ Ribéreau-Gayon et al., Handbook of Enology, Volume 2, Wiley, 2006, ISBN 9780470010396.
- ↑ Roger B. Boulton, Vernon L. Singleton, Linda F. Bisson, Ralph E. Kunkee, & 1 more, Principles and Practices of Winemaking, Springer, 31 Oct. 1998. ISBN 9780834212701.
- ↑ OIV, “Acidity and pH in wine”, https://www.oiv.int
- ↑ Peynaud, Knowing and Making Wine, Wiley, 1984, ISBN 9780471881491.
- ↑ Stevenson, The Sotheby’s Wine Encyclopedia, DK, 2011, ISBN 9780756686840.
- ↑ Markus Keller, The Science of Grapevines: Anatomy and Physiology, Academic Press Inc, 19 Jan. 2015. ISBN 9780124199873.
- ↑ Jones et al., Climate Change and Global Wine Quality, Wiley, 2012, ISBN 9781118450048.
- ↑ UC Davis, “Wine pH and quality”, https://wineserver.ucdavis.edu
- ↑ AWRI, “Managing wine pH”, https://www.awri.com.au
- ↑ Anderson & Pinilla, Wine Globalization, Cambridge University Press, 2018, ISBN 9781108445687.
- ↑ Unwin, Wine and the Vine, Routledge, 1991, ISBN 9780415042698.
- ↑ FAO, “Grape composition”, https://www.fao.org