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'''pH''' is a fundamental chemical parameter in wine, expressing the concentration of hydrogen ions and thereby the | '''pH''' is a fundamental chemical parameter in [[Wine|wine]], expressing the concentration of hydrogen ions and thereby the [[Acidity|acidity]]–alkalinity [[Balance|balance]] of [[Grape|grape]] juice and finished wine. In [[Oenology|oenology]], pH is distinct from total (titratable) acidity and plays a critical role in microbial [[Stability|stability]], [[Colour|colour]] expression, [[Oxidation|oxidation]] behaviour, and sensory perception.<ref>Robinson (ed.), ''The Oxford Companion to Wine'', Oxford University Press, 2015, ISBN 9780198705383.</ref> | ||
== Definition and measurement == | == 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.<ref>Jackson, ''Wine Science: Principles and Applications'', Academic Press, 2020, ISBN 9780128161180.</ref> | 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.<ref>Jackson, ''Wine Science: Principles and Applications'', Academic Press, 2020, ISBN 9780128161180.</ref> | ||
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.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Volume 1'', Wiley, 2006, ISBN 9780470010372.</ref> | 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.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Volume 1'', Wiley, 2006, ISBN 9780470010372.</ref> | ||
== Chemical significance == | == 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|[[Phenolic|phenolic]] compounds]]. Lower pH generally slows oxidative reactions and increases the effectiveness of [[Sulfur dioxide|sulfur dioxide]] as an antioxidant and antimicrobial agent.<ref>Waterhouse, Sacks & Jeffery, ''Understanding Wine Chemistry'', Wiley, 2016, ISBN 9781118627808.</ref> | pH strongly influences numerous chemical equilibria in wine. It affects the dissociation of organic [[Acids|acids]], the solubility of potassium salts, and the redox behaviour of [[Phenolic compounds|[[Phenolic|phenolic]] compounds]]. Lower pH generally slows oxidative reactions and increases the effectiveness of [[Sulfur dioxide|sulfur dioxide]] as an antioxidant and antimicrobial agent.<ref>Waterhouse, Sacks & Jeffery, ''Understanding Wine Chemistry'', Wiley, 2016, ISBN 9781118627808.</ref> | ||
In [[Red wines|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|browning]] over time.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Volume 2'', Wiley, 2006, ISBN 9780470010396.</ref> | In [[Red wines|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|browning]] over time.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Volume 2'', Wiley, 2006, ISBN 9780470010396.</ref> | ||
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== Viticultural factors == | == Viticultural factors == | ||
Grape pH at harvest is shaped by variety, climate, soil, and [[Vineyard|vineyard]] practices. Warmer growing conditions tend to increase grape pH through accelerated [[Malic acid|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> | Grape pH at [[Harvest|harvest]] is shaped by [[Variety|variety]], [[Climate|climate]], [[Soil|soil]], and [[Vineyard|vineyard]] practices. Warmer growing conditions tend to increase grape pH through accelerated [[Malic acid|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> | [[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|cellar]].<ref>Jones et al., ''Climate Change and Global Wine Quality'', Wiley, 2012, ISBN 9781118450048.</ref> | ||
== Winemaking control == | == Winemaking control == | ||
Winemakers may influence pH through [[Harvest timing|harvest timing]], [[Blending|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> | Winemakers may influence pH through [[Harvest timing|harvest timing]], [[Blending|blending]], acidification or deacidification, and choices affecting potassium extraction during fermentation and [[Ageing|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|wine production]].<ref>Anderson & Pinilla, ''Wine Globalization'', Cambridge University Press, 2018, ISBN 9781108445687.</ref> | The management of pH is closely linked to stylistic goals, market preferences, and regional norms, particularly in the context of globalised [[Wine production|wine production]].<ref>Anderson & Pinilla, ''Wine Globalization'', Cambridge University Press, 2018, ISBN 9781108445687.</ref> | ||