Per Dallas Morning News Article, dated 12-22-09
If you have painful sores inside your mouth and on your tongue try sauerkraut juice. It was recommended during the Great Depression from a dentist to swish your mouth with sauerkraut juice several times during the day. Swallowing about a tablespoon of juice each time may help.
The reader purchased a 79-cent can of sauerkraut (after spending $30.00 on OTC canker-sore meds) and took it home, not really thinking it would help. Within a minute, the pain was gone! The relief lasted for hours. They did not know how it worked but it did. This remedy was a lifesaver for them.