Chaptalization
The chaptalization of a wine or a must consists in adding sugar in order to obtain, after fermentation, a higher alcohol concentration.
In the case of fruit wines, this process is often necessary because a lot of fruits are too poors in sugar to get a sufficient alcoholic content, for the wine preservation for instance. It must be emphasized that the chaptalization do not lower the wine quality at all.
The yield of yeast in alcohol varies slightly depending on the yeast strain. Generally it ranges between 0.016 and 0.017 kg/L sucrose for 1 degree (% vol) ethanol. By default, the software uses 0.0165 kg/L, but this value can be modified if you know precisely the yeast strain used and its yield.