Borax is a natural mineral compound, it contains only borax. Aside from use as a cleaning agent it has been used as a preservative. As well as a bug proofer. The pioneers used it on meat to preserve and keep flies off. however, it was spread on the meat, but trimmed off and discarded prior to consumption because it has an extremely high pH and often resulted in bouts with diarrhea. Today it has uses has a hide preservative. Any residue left within the container would raise the pH of any must contacting it. Although residue starts off clear, it turns white over time. Other that that, it would not hurt as long as it was rinsed well.
