Grape composition - Revision history

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← Older revision		Revision as of 03:04, 12 January 2026
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	== Factors influencing composition ==		== Factors influencing composition ==
	Grape composition is shaped by a combination of genetic and environmental factors, including grape variety, [[climate]], [[soil]], [[vine vigour]], crop load and harvest timing.<ref>OIV, “Composition of grapes and must”.</ref> [[Vineyard]] practices such as [[irrigation]], [[canopy management]] and yield control further influence berry development and final composition.<ref>UC Davis, “Berry development and composition”.</ref>		Grape composition is shaped by a combination of genetic and environmental factors, including grape variety, [[climate]], [[soil]], [[vine vigour]], crop load and harvest timing.<ref>OIV, “Composition of grapes and must”. ISBN 9781800627048.</ref> [[Vineyard]] practices such as [[irrigation]], [[canopy management]] and yield control further influence berry development and final composition.<ref>UC Davis, “Berry development and composition”.</ref>

	Understanding these interactions is central to managing quality and achieving stylistic objectives in winemaking.		Understanding these interactions is central to managing quality and achieving stylistic objectives in winemaking.

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'''Grape composition''' refers to the physical, chemical and biochemical constituents of the grape berry that determine the potential quality, style and stability of [[wine]]. The relative proportions of [[sugars]], [[acids]], [[phenolic compounds]], aroma precursors and nutrients formed during grape development provide the fundamental [[raw material]] upon which all subsequent [[winemaking]] processes act.<ref>Robinson (ed.), ''The Oxford Companion to Wine'', Oxford University Press, 2015. ISBN 978-0198705383.</ref>

== Berry structure ==
A grape berry consists of three principal components: [[skin]], [[pulp]] and [[seeds]]. The pulp makes up the majority of the berry’s mass and contains most of the water, sugars and organic acids. The skin contains phenolic compounds, aroma precursors and pigments, while the seeds contribute [[tannins]], oils and bitter phenolics.<ref>Ribéreau-Gayon et al., ''Handbook of Enology, Vol. 2: The Chemistry of Wine'', Wiley, 2006. ISBN 978-0470010396.</ref>

The relative proportion of these components varies according to [[grape variety]], berry size and growing conditions, influencing extraction potential and wine style.

== Sugars ==
Sugars in grapes are produced through [[photosynthesis]] and accumulate primarily as glucose and fructose during ripening. Sugar concentration is a key determinant of potential [[alcohol]] content, as these sugars serve as substrates for [[yeast]] during [[fermentation]].<ref>Jackson, ''Wine Science: Principles and Applications'', 5th ed., Academic Press, 2020. ISBN 978-0128161180.</ref>

Rates of sugar accumulation are influenced by climate, [[canopy]] function, crop load and harvest timing. Excessive sugar levels may lead to high alcohol wines, while insufficient accumulation can result in under-ripe styles.

== Organic acids ==
The principal organic acids in grapes are [[tartaric acid]] and [[malic acid]]. Tartaric acid is largely stable throughout ripening, while malic acid declines as berries respire, particularly in warm conditions.<ref>Boulton et al., ''Principles and Practices of Winemaking'', Springer, 1999. ISBN 978-0834217011.</ref>

The balance between these acids defines grape and wine acidity, affecting freshness, microbial stability and [[ageing potential]].

== Phenolic compounds ==
Phenolics include tannins, anthocyanins and flavonols, located mainly in the skins and seeds. These compounds influence colour, bitterness, astringency and antioxidant capacity in wine.<ref>Waterhouse, Sacks & Jeffery, ''Understanding Wine Chemistry'', Wiley, 2016. ISBN 978-1118627808.</ref>

Phenolic maturity does not always coincide with sugar ripeness, making harvest decisions critical for [[red wine]] styles where extraction is significant.

== Aroma and flavour precursors ==
Many grape-derived aromas exist as non-volatile precursors that are transformed during fermentation and ageing. These include terpene glycosides, norisoprenoids and thiol precursors, which are particularly important in aromatic varieties.<ref>Jackson, ''Wine Science: Principles and Applications'', 5th ed., Academic Press, 2020. ISBN 978-0128161180.</ref>

The expression of varietal character depends on both grape composition at harvest and winemaking choices that preserve or enhance these compounds.

== Nitrogen and micronutrients ==
Grapes contain nitrogen in the form of amino acids and ammonium, collectively known as yeast-assimilable nitrogen. Adequate nitrogen levels are essential for healthy fermentation, while deficiencies can lead to sluggish or stuck fermentations.<ref>Amerine & Ough, ''Methods for Analysis of Musts and Wines'', Wiley, 1980. ISBN 978-0471036732.</ref>

Micronutrients such as [[potassium]], [[magnesium]] and [[trace metals]] also play roles in fermentation kinetics and wine stability.

== Factors influencing composition ==
Grape composition is shaped by a combination of genetic and environmental factors, including grape variety, [[climate]], [[soil]], [[vine vigour]], crop load and harvest timing.<ref>OIV, “Composition of grapes and must”.</ref> Vineyard practices such as [[irrigation]], [[canopy management]] and yield control further influence berry development and final composition.<ref>UC Davis, “Berry development and composition”.</ref>

Understanding these interactions is central to managing quality and achieving stylistic objectives in winemaking.

== See also ==
* [[Grape must]]
* [[Fermentation]]
* [[Phenolic compounds]]
* [[Viticulture]]

== References ==
{{reflist}}

[[Category:Viticulture]]
[[Category:Oenology]]

← Older revision		Revision as of 06:00, 17 January 2026
Line 1:		Line 1:
	'''Grape composition''' refers to the physical, chemical and biochemical constituents of the grape berry that determine the potential quality, style and stability of [[wine]]. The relative proportions of [[sugars]], [[acids]], [[phenolic compounds]], aroma precursors and nutrients formed during grape development provide the fundamental [[raw material]] upon which all subsequent [[winemaking]] processes act.<ref>Robinson ~~(ed.)~~, ''~~The~~ Oxford Companion to Wine'', Oxford University Press, 2015. ISBN ~~978-0198705383~~.</ref>		'''Grape composition''' refers to the physical, chemical and biochemical constituents of the grape berry that determine the potential quality, style and stability of [[wine]]. The relative proportions of [[sugars]], [[acids]], [[phenolic compounds]], aroma precursors and nutrients formed during grape development provide the fundamental [[raw material]] upon which all subsequent [[winemaking]] processes act.<ref>Jancis Robinson, ''Oxford Companion to Wine'', Oxford University Press, 17 Sept. 2015. ISBN 9780198705383.</ref>

	== Berry structure ==		== Berry structure ==
Line 7:		Line 7:

	== Sugars ==		== Sugars ==
	Sugars in grapes are produced through [[photosynthesis]] and accumulate primarily as glucose and fructose during ripening. [[Sugar]] concentration is a key determinant of potential [[alcohol]] content, as these sugars serve as substrates for [[yeast]] during [[fermentation]].<ref>Jackson, ''Wine Science: Principles and Applications''~~, 5th ed.~~, Academic Press, 2020. ISBN ~~978-0128161180~~.</ref>		Sugars in grapes are produced through [[photosynthesis]] and accumulate primarily as glucose and fructose during ripening. [[Sugar]] concentration is a key determinant of potential [[alcohol]] content, as these sugars serve as substrates for [[yeast]] during [[fermentation]].<ref>PhD Jackson, Ronald S., ''Wine Science: Principles and Applications'', Academic Press Inc, 14 April 2020. ISBN 9780128161180.</ref>

	Rates of sugar accumulation are influenced by climate, [[canopy]] function, crop load and harvest timing. Excessive sugar levels may lead to high alcohol wines, while insufficient accumulation can result in under-ripe styles.		Rates of sugar accumulation are influenced by climate, [[canopy]] function, crop load and harvest timing. Excessive sugar levels may lead to high alcohol wines, while insufficient accumulation can result in under-ripe styles.

	== Organic acids ==		== Organic acids ==
	The principal organic acids in grapes are [[tartaric acid]] and [[malic acid]]. [[[[Tartaric]] acid]] is largely stable throughout ripening, while malic acid declines as berries respire, particularly in warm conditions.<ref>Boulton ~~et al~~., ''Principles and Practices of Winemaking'', Springer, ~~1999~~. ISBN ~~978-0834217011~~.</ref>		The principal organic acids in grapes are [[tartaric acid]] and [[malic acid]]. [[[[Tartaric]] acid]] is largely stable throughout ripening, while malic acid declines as berries respire, particularly in warm conditions.<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>

	The balance between these acids defines grape and wine acidity, affecting freshness, microbial stability and [[ageing potential]].		The balance between these acids defines grape and wine acidity, affecting freshness, microbial stability and [[ageing potential]].

	== Phenolic compounds ==		== Phenolic compounds ==
	Phenolics include tannins, anthocyanins and flavonols, located mainly in the skins and seeds. These compounds influence colour, bitterness, astringency and antioxidant capacity in wine.<ref>Waterhouse~~, Sacks & Jeffery~~, ''Understanding Wine Chemistry'', Wiley, 2016. ISBN ~~978-1118627808~~.</ref>		Phenolics include tannins, anthocyanins and flavonols, located mainly in the skins and seeds. These compounds influence colour, bitterness, astringency and antioxidant capacity in wine.<ref>Andrew L. Waterhouse, ''Understanding Wine Chemistry'', Wiley, 19 Aug. 2016. ISBN 9781118627808.</ref>

	[[Phenolic maturity]] does not always coincide with sugar ripeness, making harvest decisions critical for [[red wine]] styles where extraction is significant.		[[Phenolic maturity]] does not always coincide with sugar ripeness, making harvest decisions critical for [[red wine]] styles where extraction is significant.

	== Aroma and flavour precursors ==		== Aroma and flavour precursors ==
	Many grape-derived aromas exist as non-volatile precursors that are transformed during fermentation and ageing. These include terpene glycosides, norisoprenoids and thiol precursors, which are particularly important in aromatic varieties.<ref>Jackson, ''Wine Science: Principles and Applications''~~, 5th ed.~~, Academic Press, 2020. ISBN ~~978-0128161180~~.</ref>		Many grape-derived aromas exist as non-volatile precursors that are transformed during fermentation and ageing. These include terpene glycosides, norisoprenoids and thiol precursors, which are particularly important in aromatic varieties.<ref>PhD Jackson, Ronald S., ''Wine Science: Principles and Applications'', Academic Press Inc, 14 April 2020. ISBN 9780128161180.</ref>

	The expression of varietal character depends on both grape composition at harvest and winemaking choices that preserve or enhance these compounds.		The expression of varietal character depends on both grape composition at harvest and winemaking choices that preserve or enhance these compounds.
Line 32:		Line 32:

	== Factors influencing composition ==		== Factors influencing composition ==
	Grape composition is shaped by a combination of genetic and environmental factors, including grape variety, [[climate]], [[soil]], [[vine vigour]], crop load and harvest timing.<ref>~~OIV~~, ~~“Composition of grapes and must”~~. ISBN 9781800627048.</ref> [[Vineyard]] practices such as [[irrigation]], [[canopy management]] and yield control further influence berry development and final composition.<ref>UC Davis, “Berry development and composition”.</ref>		Grape composition is shaped by a combination of genetic and environmental factors, including grape variety, [[climate]], [[soil]], [[vine vigour]], crop load and harvest timing.<ref>Glen Creasy, Leroy Creasy, ''Grapes'', CABI Publishing, November 1, 2025. ISBN 9781800627048.</ref> [[Vineyard]] practices such as [[irrigation]], [[canopy management]] and yield control further influence berry development and final composition.<ref>UC Davis, “Berry development and composition”.</ref>

	Understanding these interactions is central to managing quality and achieving stylistic objectives in winemaking.		Understanding these interactions is central to managing quality and achieving stylistic objectives in winemaking.

← Older revision		Revision as of 21:00, 10 January 2026
Line 7:		Line 7:

	== Sugars ==		== Sugars ==
	Sugars in grapes are produced through [[photosynthesis]] and accumulate primarily as glucose and fructose during ripening. Sugar concentration is a key determinant of potential [[alcohol]] content, as these sugars serve as substrates for [[yeast]] during [[fermentation]].<ref>Jackson, ''Wine Science: Principles and Applications'', 5th ed., Academic Press, 2020. ISBN 978-0128161180.</ref>		Sugars in grapes are produced through [[photosynthesis]] and accumulate primarily as glucose and fructose during ripening. [[Sugar]] concentration is a key determinant of potential [[alcohol]] content, as these sugars serve as substrates for [[yeast]] during [[fermentation]].<ref>Jackson, ''Wine Science: Principles and Applications'', 5th ed., Academic Press, 2020. ISBN 978-0128161180.</ref>

	Rates of sugar accumulation are influenced by climate, [[canopy]] function, crop load and harvest timing. Excessive sugar levels may lead to high alcohol wines, while insufficient accumulation can result in under-ripe styles.		Rates of sugar accumulation are influenced by climate, [[canopy]] function, crop load and harvest timing. Excessive sugar levels may lead to high alcohol wines, while insufficient accumulation can result in under-ripe styles.

	== Organic acids ==		== Organic acids ==
	The principal organic acids in grapes are [[tartaric acid]] and [[malic acid]]. Tartaric acid is largely stable throughout ripening, while malic acid declines as berries respire, particularly in warm conditions.<ref>Boulton et al., ''Principles and Practices of Winemaking'', Springer, 1999. ISBN 978-0834217011.</ref>		The principal organic acids in grapes are [[tartaric acid]] and [[malic acid]]. [[[[Tartaric]] acid]] is largely stable throughout ripening, while malic acid declines as berries respire, particularly in warm conditions.<ref>Boulton et al., ''Principles and Practices of Winemaking'', Springer, 1999. ISBN 978-0834217011.</ref>

	The balance between these acids defines grape and wine acidity, affecting freshness, microbial stability and [[ageing potential]].		The balance between these acids defines grape and wine acidity, affecting freshness, microbial stability and [[ageing potential]].
Line 19:		Line 19:
	Phenolics include tannins, anthocyanins and flavonols, located mainly in the skins and seeds. These compounds influence colour, bitterness, astringency and antioxidant capacity in wine.<ref>Waterhouse, Sacks & Jeffery, ''Understanding Wine Chemistry'', Wiley, 2016. ISBN 978-1118627808.</ref>		Phenolics include tannins, anthocyanins and flavonols, located mainly in the skins and seeds. These compounds influence colour, bitterness, astringency and antioxidant capacity in wine.<ref>Waterhouse, Sacks & Jeffery, ''Understanding Wine Chemistry'', Wiley, 2016. ISBN 978-1118627808.</ref>

	Phenolic maturity does not always coincide with sugar ripeness, making harvest decisions critical for [[red wine]] styles where extraction is significant.		[[Phenolic maturity]] does not always coincide with sugar ripeness, making harvest decisions critical for [[red wine]] styles where extraction is significant.

	== Aroma and flavour precursors ==		== Aroma and flavour precursors ==
Line 32:		Line 32:

	== Factors influencing composition ==		== Factors influencing composition ==
	Grape composition is shaped by a combination of genetic and environmental factors, including grape variety, [[climate]], [[soil]], [[vine vigour]], crop load and harvest timing.<ref>OIV, “Composition of grapes and must”.</ref> Vineyard practices such as [[irrigation]], [[canopy management]] and yield control further influence berry development and final composition.<ref>UC Davis, “Berry development and composition”.</ref>		Grape composition is shaped by a combination of genetic and environmental factors, including grape variety, [[climate]], [[soil]], [[vine vigour]], crop load and harvest timing.<ref>OIV, “Composition of grapes and must”.</ref> [[Vineyard]] practices such as [[irrigation]], [[canopy management]] and yield control further influence berry development and final composition.<ref>UC Davis, “Berry development and composition”.</ref>

	Understanding these interactions is central to managing quality and achieving stylistic objectives in winemaking.		Understanding these interactions is central to managing quality and achieving stylistic objectives in winemaking.