posted 12 years ago
Salt is not needed to preserve food by canning. In other food preservation methods, for example drying meats, salt is needed to inhibit growth of spoilage bacteria. Then, as meat keeps on drying, less moisture is available to bacteria and meat becomes more stable. Salt, however, does not evaporate and remains inside of the meat. This increases proportion of salt in relation to meat's weight and bacteria cannot grow.
Canning preserves food by destroying bacteria with heat or rendering them ineffective by applying moderate heat and introducing acidity. This is why canning jams, jellies or fruit is so easy as all those foods contain some acidity.
Meats and vegetables don't contain acidity and must be processed at 240 F. Although processing at boiling water temperature (212 F) will kill bacteria anyhow, nevertheless Clostridium botulinum bacterial spores can survive 212 F for 5 hours. That is why we have to use a pressure canner so the temperature will reach 240 F. The role of salt, however, is of no significance, because all bacteria and bacterial spores will be killed.