1. Increase the curing time: it takes some time to cure pickled cabbage. If the time is not long enough, the sauerkraut will not turn sour, and the pickling time can be extended until the sauerkraut turns sour.
2. Reduce the curing temperature: If the curing temperature of sauerkraut is too high, sauerkraut will not turn sour easily. You can pickle sauerkraut in the shade, or you can put the pickled sauerkraut container in the refrigerator.