Yes, sugar should be added on the second or third day after the start of fermentation, when the fermentation is the most vigorous, the yeast content in the wine reaches the maximum, and the yeast is vigorous. Adding sugar at this time is beneficial to the thorough fermentation, leaving no residual sugar and ensuring the stability of the wine. Residual sugar will be decomposed by lactic acid bacteria, which will bring irritation and bitterness. Sugar is added twice, with an interval of 1-2 days. What is mentioned above is red wine, and white wine can retain residual sugar into 8 grams of semi-dry. However, white wine should avoid malic acid-lactic acid fermentation. After alcohol fermentation (5-6 days), immediately separate the wine feet, fill the container, cool down to 17 degrees, and conditionally add SO2 to close the container.

"malolactic fermentation" refers to red wine. It's the conversion of acid, and it doesn't produce alcohol.