The practice of homemade wine:

1 Cut the grapes one by one as shown in the figure. Don't break the skin, not at all, or it will affect the quality. Then just put the dust on the surface in the water. Don't rub it with your hands, don't brush it with a brush, and don't disinfect the grapes. The white film on the surface is fermented. Make sure the survival of wild yeast.

2. After the grapes are washed, put them in a basket to fully dry the water, or hang them up to dry.

3. First fermentation: The method of crushing is very simple, that is, crush the grapes, just separate the skins and flesh, put them together with the skins and seeds, and put them in two-thirds of the container (the remaining space is reserved for the grape skins to rise during fermentation).

4. Sugar is generally added several times. For the first time, add half of the grapes 24 hours after filling, and add the rest after 3-4 days depending on the fermentation situation. After the grapes are bottled, cover the bottle (don't cover it tightly, leave an air outlet, as long as there is no dust).

5. After a week or so, the fermentation residue is separated from the liquor, and the fermentation is stopped naturally after the sugar is consumed, and the peel no longer floats up, that is, the fermentation stop point is reached. However, if too much sugar is added, the fermentation stop point is not reached after 7 days, the yeast is still multiplying and fermenting in large quantities, and the wine is still bubbling with carbon dioxide in large quantities. At this time, if it is sealed immediately, the pressure in the bottle will increase during post-fermentation, and the cork may be pushed open and the wine will be ejected. Therefore, it is necessary to wait for the wine to stop bubbling a lot before sealing.

6. A small amount of delicate foam will be produced in the second fermentation. After 2 to 3 weeks, the liquor is particularly clear. The second fermentation is not by yeast fermentation, but by malic acid and lactic acid fermentation, so it will not produce a lot of carbon dioxide, and the pressure in the bottle will not continue to increase, so there is no danger of bottle explosion. So fill the container as much as possible and tighten the bottle cap.

7. Finished product drawing.

Hazards of homemade wine:

Wang Xinghong, an associate researcher at the School of Life Sciences of Yunnan University, once pointed out that the main metabolite of yeast in wine fermentation is ethanol, but it also produces methanol. Home-brewed wine is allowed in foreign countries, but brandy is not allowed to be purified by distillation, because if you don't know fractionation, it will easily cause harmful substances to concentrate.

Methanol is highly toxic and used in industry. Some "fake liquors" cause the blindness and death of the victims, mostly because the liquor is doped with methanol.

Experts pointed out that the edible grapes sold in the market are often not suitable for wine making, because the tannin content of edible grapes is relatively small, and tannin is an important substance in wine. Homemade wine should be made of relatively reliable glass and ceramic utensils, and the temperature during fermentation should not be too high.

Baidu encyclopedia-homemade wine