Canning is the most complicated and time consuming of the home food preservation methods. Canning and preserving require big kettles, canning jars, rings and lids, and other specialized equipment. Low-acid foods such as corn, peas, and beans must be processed in canning-sized pressure cookers.
Sealed jars of jams and preserves, such as tomato puree, are sterilized in a boiling-water bath—in a large canning kettle with boiling water to a depth of 2 to 4 inches over the tops of the canning jars.
Home canning is not recommended for most vegetables. There is potential for contamination in under-processed foods, and one must weigh the risks inherent in such an undertaking. Given the relative ease and speed with which homegrown vegetables can be frozen, and the quality of the finished product, it is not surprising that most contemporary gardeners and cooks opt for this method of food preservation.
However, some specialty foods, such as pickles and jams, can only be prepared by canning. Can food when the effect is more than just preserving the harvest.