Commercial wine (table) is 10% alcohol. Beer between 3-5% and spirits 40% alcohol.
However most Indian homebrew want to make as strong a wine as possible. They add so much sugar that yeast practically choke.
Myth 1: Adding too much sugar in the beginning will produce strong wine
Myth 2: Sweet/Desert wine has excess sugar to begin with
Myth 3: (laziness actually) who will open the fermentor multiple times, lets add all the sugar in one go.
This has a couple of unwanted effects:
1. Sugar esp. at S.G. >1.1 starts acting as a preservative and inhibits microbial life. This makes the yeast stressed and produces off flavors.
2. The probability of stuck fermentation becomes high as the must (fruit juice) is not the best home for the wines.
3. Sulphite (rotten egg) smells sometimes comes and overpowers the natural aromas of your fruits. Typically if you use wine yeast (not baking yeast) and adequate amount of yeast nutrient sulfide and off flavors can be avoided. However stressed yeast produces off flavors. Additionally you could use copper suphate (blue vitrol) to reduce these flavors.
4. Incomplete fermentation (like the batch in the picture Below)
What is the correct process:
1. Always add sugar and yeast nutrients in steps. (1/3 at the beginning of fermentation, 1/3 at the time of transfer from primary to secondary and 1/3 towards finishing)
2. To create sweet wine, use potassium sorbate to inhibit all yeast activity. Then add sugar just before bottling. Drowning them in sugar on day one will only lead to uncertainity in final alcohol levels and sweetness.