Estimating potential alcohols based on grape must analysis is not as straightforward as many winemakers assume. This article by the Australian Wine Research Institute addresses some key points to be taken into account.
The science
Theoretically, yeast converts sugar into almost equal masses of ethanol and carbon dioxide (CO2) gas by the Gay-Lussac equation. In reality, however, some sugar is converted to energy and yeast cell growth (biomass production) and some ethanol vapour is lost to the environment. Ethanol yields are only ever around 90% of the theoretical value…
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