Long term food storage is very important in urban homesteading today. After a successful season, the homesteader is wise to preserve their harvest. They worked hard and planted extra so as to supply their needs beyond just the summer harvest, and need to be prepared to preserve the fruits of their labor.
There are a few options for food storage, such as dehydration or freezing, but the long term food storage method for today's discussion is canning food. Canning food can be done to store the fruit or vegetable itself, such as peaches or tomatoes, or it can be done for creating staples from recipes like a peach jelly, or tomato paste.
Home canning has been done for ages. The basic principle of canning, for food safety, is to expose the food to a high temperature, that will stop decay and bacteria in the food. Sterile, airtight containers, generally glass jars with removable seals and ringed bands, are used to package the food, and then they are exposed to a high temperature, either through pressure canning or using a water bath canner.
While many foods can be safely canned in a water bath, those with a lower acidity are the exception, and should be preserved by using the pressure canning method. Many vegetables, like corn, carrots, squash, beans, mushrooms, spinach, bell peppers, and asparagus have a lower acidity and should be pressure canned. Meats should also be pressure canned.
A general rule of thumb, higher acidity foods can be preserved in using water bath canning, and lower acidity foods should be preserved using a pressure canning. Specifically, foods above 4.5 pH may be safely canned in a water bath canner at 212 F. Foods below 4.5 ph need to be processed using a pressure canner at 250 F or higher.
Whether you are using a water bath or a pressure canner, a rack is needed to keep the jars off the bottom of the canner. Glass heats more slowly than metal and jars are more liable to crack as a result.
There is great information all over the web and in books that can be helpful resources for long term food storage. Things like a pH chart of commonly canned foods, and information about why foods spoil, botulism, and various methods of preserving food including canning, pressure cooking, freezing, drying, root-cellaring, and curing.
http://www.urbanhomesteadingtoday.com is a website that is focused on urban homesteading today and the topics relevant to how to develop your own homestead. It is a place where you can join the journey, and learn to become more self reliant and less dependent on our currently over taxed support systems.