If you make it yourself, because you use fresh grapes and the sugar content is not high enough, you should add sugar. As for pressure or not, in fact, anything can be done. Yeast can ferment through grape skins, but the whole grape will have less alcohol after fermentation. In beaujolais, France, they used a grape called Jiamei to brew the world-famous Beaujolais new wine through carbon dioxide impregnation. Here, the grapes are not broken, but the whole fermentation. Whole grains are not crushed after fermentation and need to be squeezed. Self-brewed hand-squeezed juice. The fermentation temperature of red wine is 22-32℃, so 24℃ should be quite suitable. Do it several times more and accumulate experience.

One: Cut the grapes one by one with scissors, pick out the bad grapes and throw them away, then wash them with water and dry them.

Two: Grab a few grapes at a time, crush them together and put them in a clean jar (a larger jar is also acceptable), and fill them with two thirds, leaving one third of the space.

Three: grapes are naturally fermented in a jar for a week. After fermentation, the skins of grapes will rise like porridge, so the jar can't be too full.

Four: After a week, filter the fermented grapes with a clean cloth, and separate the skins and cores of the grapes, leaving only the grape juice.

Five: A week after the grape juice is precipitated, there is a thick layer of grape starch under the jar. Scoop out the cold part first, fold it with cloth, and filter the rest again. Starch must be filtered out, otherwise the wine will be very turbid. Four or five processes are troublesome and need enough patience.

6. Put the filtered grape juice into the jar according to the ratio of 10 kg of grapes and 1 kg of rock sugar, break it with eggs, pour out only the egg white, put it into the jar, seal the jar mouth with plastic bags and rubber bands, then store it in a sealed way and drink it after three months. The amount of sugar can be adjusted according to your own taste.