1，發酵時間太長，沒有及時終止發酵，沒有及時倒桶，俗話說叫發酵過了，酒變成了醋。
2，另壹種原因是酒液被醋酸菌汙染，酒液變質，變酸，這種情況是不能飲用的。
自釀葡萄酒的方法如下：
材料：新鮮的葡萄，白糖，容器。
第壹步，去市場購買新鮮的葡萄，把壞掉的葡萄挑出來。
/iknow-pic.cdn.bcebos.com/aec379310a55b3197cd2e0314ea98226cffc174e"target="_blank"title=""class="ikqb_img_alink">/iknow-pic.cdn.bcebos.com/aec379310a55b3197cd2e0314ea98226cffc174e?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto"esrc="/aec379310a55b3197cd2e0314ea98226cffc174e"/>
第二步，洗幹凈葡萄然後泡半小時淡鹽水，再沖洗壹遍。
/iknow-pic.cdn.bcebos.com/9c16fdfaaf51f3de99e2db2099eef01f3a297925"target="_blank"title=""class="ikqb_img_alink">/iknow-pic.cdn.bcebos.com/9c16fdfaaf51f3de99e2db2099eef01f3a297925?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto"esrc="/9c16fdfaaf51f3de99e2db2099eef01f3a297925"/>
第三步，沖洗完成後放在外面幹凈的地方晾幹，不要讓葡萄把多余的水分帶進去。
/iknow-pic.cdn.bcebos.com/0b55b319ebc4b745dabfd552c2fc1e178a82154e"target="_blank"title=""class="ikqb_img_alink">/iknow-pic.cdn.bcebos.com/0b55b319ebc4b745dabfd552c2fc1e178a82154e?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto"esrc="/0b55b319ebc4b745dabfd552c2fc1e178a82154e"/>
第四步，把晾幹的葡萄捏碎後放入容器內，按照6斤葡萄1斤白糖的比例來放入白糖，然後攪拌均勻把蓋子密封好。
/iknow-pic.cdn.bcebos.com/d62a6059252dd42ac7cb62ef0e3b5bb5c8eab8b0"target="_blank"title=""class="ikqb_img_alink">/iknow-pic.cdn.bcebos.com/d62a6059252dd42ac7cb62ef0e3b5bb5c8eab8b0?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto"esrc="/d62a6059252dd42ac7cb62ef0e3b5bb5c8eab8b0"/>
第五步，夏季發酵壹周就可以了，秋季溫度低的話要半個月的時間發酵。
/iknow-pic.cdn.bcebos.com/aa64034f78f0f7363cd52e450755b319ebc4134e"target="_blank"title=""class="ikqb_img_alink">/iknow-pic.cdn.bcebos.com/aa64034f78f0f7363cd52e450755b319ebc4134e?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto"esrc="/aa64034f78f0f7363cd52e450755b319ebc4134e"/>
第六步，發酵完後，用濾網過濾出來葡萄酒，可以多過濾幾遍再裝進酒瓶中。
/iknow-pic.cdn.bcebos.com/242dd42a2834349bf2c40dc1c4ea15ce37d3beb0"target="_blank"title=""class="ikqb_img_alink">/iknow-pic.cdn.bcebos.com/242dd42a2834349bf2c40dc1c4ea15ce37d3beb0?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto"esrc="/242dd42a2834349bf2c40dc1c4ea15ce37d3beb0"/>