The water bath processing method is fairly simple and inexpensive. The filled canning jars are placed in the Canner,
If a food is naturally high in acid (most fruits for example) or if acid is added to the food (for example the vinegar in pickles), then the acid helps to prevent the growth of bacteria. The heat from the boiling water is enough to destroy any harmful organisms that can survive in the acid. 
If the food is low in acid content (vegetables for example) then the temperature of boiling water is not enough to destroy the harmful bacteria that can live in these foods. Although it is more expensive, a pressure canner should be used for these foods. By increasing the pressure, we also raise the boiling point of the water and thus increase the temperature at which the filled canning jars are processed.
Fortunately good canning recipes tell us which method to use. For somebody who is new to canning, the Ball Blue Book 
One final comment about food safety is that the recipes need to be adjusted for high altitude. For the water bath method, the processing time needs to be increased. For the pressure canner method, the processing pressure needs to be increased. Reliable recipes will tell you what adjustments to make.
You can get more free information from the USDA Principles of home canning.
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Three Ingredient Fig Jam for Canning
1 year ago
So if you were just getting started, which would you invest in? Can you use the pressure canner for preserving foods that only require a water bath? I only want to get one, since I don't have the space for two, but I'd like it to be versatile enough to last, well, forever.
ReplyDeleteI've never tried using a pressure canner for a food that only require water bath. As far as food safety goes, there would be no problem there. I don't know if processing the food at a higher temperature might cause it to have an over-cooked taste.
ReplyDeleteIf you could find a loose fitting lid that is large enough to cover the pressure canner then using this lid instead of the tight fitting pressure lid would basically turn your pressure canner into a water bath canner.
I definitely would only use the pressure lid if you plan to fasten it down properly and use the pressure method. You don't want an improperly fastned lid to come flying off from your canner.
You said in another comment that your goal is to can fruit. For fruit, all you need is a water bath. If you plan to expand into vegetables, then you need a pressure canner.