Canning is the process whereby one can preserve food for long-term storage in a non-refrigerated pantry.
The type of canning I have had experience with is water-bath canning. This method is suitable for high-acid, plant-based foods such as rhubarb, tomatoes, berries, stone fruit, etc. I, personally, have canned tomatoes, peaches, and blueberries, with particularly extensive experience with tomatoes. The essentials of the process are as follows, with full detail usually contained within the user manuals of canning kits and canning equipment along with essential kitchen wisdom on such things as insulating certain counter surfaces against direct heat, etc.
To use this method, I first select the fresh food I wish to preserve, wash it thoroughly, and excise any blemishes, cores, stems, peels, etc. In the case of the tomatoes, this usually involves also preparing them into a sauce form and then keeping the sauce warm until the preparations for the actual canning process have been completed. For peaches and blueberries I simply prepare a light syrup and then choose whether to keep it cool or warm for packing into the jars and adjust my other preparations accordingly. I add extra acid, such as apple cider vinegar, to the food to ensure that there is enough acidity to preserve the food against spoliation.
Preparing for the canning process involves prayer, along with meticulously cleaning every mason jar, working surface, utensil, and towel used in the process in order to minimize the initial amount of pathogens and other food-spoiling agents allowed into the mason jars. Mason jars are the glass containers available for canning food at home. The process also requires a large and sturdy-enough pot to hold potentially a gallon’s worth of pint or quart jars, or one half-gallon jar, plus enough water to surround and cover the jars. To ensure that the mason jars are tempered sufficiently to withstand hot water without cracking, I submerge them in simmering water until the food is prepared.
Then, I lift them out with tongs and fill them with food, measuring the exact requirement of headspace for the particular food between the upper surface of the food and the rim of the jar. I ensure that the jars are not damaged, the rims are clean, and the lids new before placing the lids on the jars and screwing the bands on to hold the lids against the jar rims (finger-tight but not excessively). Careful not to tilt them, I then place the jars into the simmering water on a rack so as to avoid heat conducting directly from stove-to oven-to jar. I then bring the water to boiling and then time the boiling based upon the specific food I am canning. The boiling water heats the food, working in tandem with the acid and sugar to destroy pathogens and other colonists and to fix the food into a preserved state. The heated food also expands into the headspace, forcing the air out past the seal between the rim and the lid. After that, I remove the jars and wait for the food to cool. During the first few minutes, I listen and watch for the lids to pop from their convex shape to a concave shape, indicating the formation of a relative vacuum inside the jar which has successfully and fully sealed the food away from the elements. I further confirm success by tapping the jars with my finger or a spoon. If I feel the lid is firm when I tap it with my finger, it is successful, but if it flexes, it is not. If the lid produces a crisp “ding” when tapped with a spoon, it is successful, but if the sound is dull, it is not. I immediately use, refrigerate, or freeze any unsuccessful jars’ contents.
All told, this process takes several strenuous hours involving strategic use of kitchen space, which can feel surprisingly crowded even in large residential kitchens given the logistic entail. However, both the journey and the results are very rewarding, among them, namely, my “Awesome Sauce” tomato sauce. The food lasts for between 12 and 18 months without the need for any precautions aside from avoiding jar breakage.