Yeast metabolism: Difference between revisions

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'''Yeast metabolism''' refers to the biochemical processes by which [[yeast]] converts substrates in [[grape must]] into [[ethanol]], [[carbon dioxide]] and a wide range of secondary metabolites during [[alcoholic fermentation]]. In winemaking, yeast metabolism is central to fermentation kinetics, alcohol production, aroma formation and overall wine balance.<ref>Jackson, ''Wine Science: Principles and Applications''~~, 5th ed.~~, Academic Press, 2020, ISBN 9780128161180.</ref>

'''Yeast metabolism''' refers to the biochemical processes by which [[yeast]] converts substrates in [[grape must]] into [[ethanol]], [[carbon dioxide]] and a wide range of secondary metabolites during [[alcoholic fermentation]]. In winemaking, yeast metabolism is central to fermentation kinetics, alcohol production, aroma formation and overall wine balance.<ref>PhD Jackson, Ronald S., ''Wine Science: Principles and Applications'', Academic Press Inc, 14 April 2020. ISBN 9780128161180.</ref>

== Role in winemaking ==

During fermentation, yeasts—most commonly strains of ''[[Saccharomyces cerevisiae]]''—metabolise [[sugar]] primarily in the form of [[glucose]] and [[fructose]]. Through glycolysis and subsequent metabolic pathways, sugars are converted into ethanol and carbon dioxide, while energy is generated to sustain yeast growth and reproduction.<ref>Boulton ~~et al~~., ''Principles and Practices of Winemaking'', Springer, ~~1999,~~ ISBN ~~9780834217011~~.</ref>

During fermentation, yeasts—most commonly strains of ''[[Saccharomyces cerevisiae]]''—metabolise [[sugar]] primarily in the form of [[glucose]] and [[fructose]]. Through glycolysis and subsequent metabolic pathways, sugars are converted into ethanol and carbon dioxide, while energy is generated to sustain yeast growth and reproduction.<ref>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.</ref>

Beyond alcohol production, yeast metabolism is responsible for the formation of numerous compounds that shape wine aroma, flavour and texture, making yeast selection and fermentation management critical oenological decisions.

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* Reduction of pyruvate to ethanol

These processes are influenced by temperature, oxygen availability and nutrient status of the must, particularly [[nitrogen]] content.<ref>Ribéreau-Gayon ~~et al.~~, ''Handbook of Enology, Volume 1'', Wiley, 2006, ISBN 9780470010372.</ref>

These processes are influenced by temperature, oxygen availability and nutrient status of the must, particularly [[nitrogen]] content.<ref>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.</ref>

== Secondary metabolites ==

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== Nitrogen and yeast health ==

Assimilable nitrogen is a key factor regulating yeast metabolism. Insufficient nitrogen can lead to sluggish or [[stuck fermentation]], while excess nitrogen may increase the formation of undesirable by-products. Winemakers often manage nitrogen levels through vineyard practices or controlled additions in the cellar.<ref>Waterhouse~~, Sacks & Jeffery~~, ''Understanding Wine Chemistry'', Wiley, 2016, ISBN 9781118627808.</ref>

Assimilable nitrogen is a key factor regulating yeast metabolism. Insufficient nitrogen can lead to sluggish or [[stuck fermentation]], while excess nitrogen may increase the formation of undesirable by-products. Winemakers often manage nitrogen levels through vineyard practices or controlled additions in the cellar.<ref>Andrew L. Waterhouse, ''Understanding Wine Chemistry'', Wiley, 19 Aug. 2016. ISBN 9781118627808.</ref>

== Oxygen and metabolism ==

@@ Line 1: / Line 1: @@
-'''Yeast metabolism''' refers to the biochemical processes by which [[yeast]] converts substrates in [[grape must]] into [[ethanol]], [[carbon dioxide]] and a wide range of secondary metabolites during [[alcoholic fermentation]]. In winemaking, yeast metabolism is central to fermentation kinetics, alcohol production, aroma formation and overall wine balance.<ref>Jackson, ''Wine Science: Principles and Applications'', 5th ed., Academic Press, 2020, ISBN 9780128161180.</ref>
+'''Yeast metabolism''' refers to the biochemical processes by which [[yeast]] converts substrates in [[grape must]] into [[ethanol]], [[carbon dioxide]] and a wide range of secondary metabolites during [[alcoholic fermentation]]. In winemaking, yeast metabolism is central to fermentation kinetics, alcohol production, aroma formation and overall wine balance.<ref>PhD Jackson, Ronald S., ''Wine Science: Principles and Applications'', Academic Press Inc, 14 April 2020. ISBN 9780128161180.</ref>
 == Role in winemaking ==
-During fermentation, yeasts—most commonly strains of ''[[Saccharomyces cerevisiae]]''—metabolise [[sugar]] primarily in the form of [[glucose]] and [[fructose]]. Through glycolysis and subsequent metabolic pathways, sugars are converted into ethanol and carbon dioxide, while energy is generated to sustain yeast growth and reproduction.<ref>Boulton et al., ''Principles and Practices of Winemaking'', Springer, 1999, ISBN 9780834217011.</ref>
+During fermentation, yeasts—most commonly strains of ''[[Saccharomyces cerevisiae]]''—metabolise [[sugar]] primarily in the form of [[glucose]] and [[fructose]]. Through glycolysis and subsequent metabolic pathways, sugars are converted into ethanol and carbon dioxide, while energy is generated to sustain yeast growth and reproduction.<ref>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.</ref>
 Beyond alcohol production, yeast metabolism is responsible for the formation of numerous compounds that shape wine aroma, flavour and texture, making yeast selection and fermentation management critical oenological decisions.
@@ Line 12: / Line 12: @@
 * Reduction of pyruvate to ethanol
-These processes are influenced by temperature, oxygen availability and nutrient status of the must, particularly [[nitrogen]] content.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Volume 1'', Wiley, 2006, ISBN 9780470010372.</ref>
+These processes are influenced by temperature, oxygen availability and nutrient status of the must, particularly [[nitrogen]] content.<ref>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.</ref>
 == Secondary metabolites ==
@@ Line 26: / Line 26: @@
 == Nitrogen and yeast health ==
-Assimilable nitrogen is a key factor regulating yeast metabolism. Insufficient nitrogen can lead to sluggish or [[stuck fermentation]], while excess nitrogen may increase the formation of undesirable by-products. Winemakers often manage nitrogen levels through vineyard practices or controlled additions in the cellar.<ref>Waterhouse, Sacks & Jeffery, ''Understanding Wine Chemistry'', Wiley, 2016, ISBN 9781118627808.</ref>
+Assimilable nitrogen is a key factor regulating yeast metabolism. Insufficient nitrogen can lead to sluggish or [[stuck fermentation]], while excess nitrogen may increase the formation of undesirable by-products. Winemakers often manage nitrogen levels through vineyard practices or controlled additions in the cellar.<ref>Andrew L. Waterhouse, ''Understanding Wine Chemistry'', Wiley, 19 Aug. 2016. ISBN 9781118627808.</ref>
 == Oxygen and metabolism ==