The process of canning is simple, and involves placing perishable foods in jars or bottles, then cooking the contents to a temperature that halts any enzymatic activity occurring within the foods. The goal is to stall any microbial growth, which can be affected by moisture, air, light, or even decay over time.
The canning of food first came about during the Napoleonic Wars in 19th century France. The French regime offered a reward for anyone who could come up with a cheap and efficient way to transport food for soldiers. Chef Nicolas Appert discovered that food, when cooked in glass, did not spoil unless air breached the container. He reported his findings to the French Directory, and used his reward money to perfect and grow his method, eventually opening the first commercial cannery in 1812.
Outside of practical reasons, canning is valued for how quick and easy it can be. Canning has seen a resurgence, especially during the pandemic, when people have had the time to choose healthy options and go through the steps of the canning process. Those who grow their own fruits or vegetables in home gardens, or who are trying to be conscious of BPA, additives, or other chemicals in commercial packaging can benefit from learning to can.
Before starting any method of canning, always wash and thoroughly rinse jars to kill off bacteria, and check jars and lids for cracks, chips, or dents, which will prevent an airtight seal and cause spoilage.
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Tools for Home Canning
You will also need:
A jar lifter – a specialized set of large tongs that are sturdy enough to lift heavy glass jars, made to absorb and deflect the heat created by the water bath or pressure cooking methods used to sterilize the food
Canning funnel – a wide, collapsible, often silicone funnel meant to easily transfer ingredients into canning containers for efficient cooking and less mess
Knives, a food processor, or blender – these utensils will assist in cutting up or breaking down foods to the desired consistency for your recipe
A ladle – for spooning any ingredients into the jar
Clean dish towels – useful for wiping off the lids of the jars before closing the lid for maximum seal. Also for wiping down countertops!
Bubble freer and headspace tool – if air bubbles are not thoroughly removed from your canning jars, issues with pressure can arise. A bubble freer is used to slip between the food and the insides of the canning jar to allow air bubbles to rise to the top. A non-metal spatula or wide knife can achieve the same results, though usually, bubble freers come with measurement marks on the side edge to gauge how much free space you still have at the top of your jar
A large, elevated cooling rack – canning containers must be cooled thoroughly for 12 to 24 after cooking, depending on the recipe. Having a secure place where jars can cool and settle without temperature change or movement is necessary
Methods of Home Canning:
Hot Water Bath Canning:
The most common method for the preparation of canned food is a boiling water bath, which is done exactly how it sounds. In this method, glass jars are submerged completely in water and brought to a boil (212 degrees Fahrenheit or higher), usually for about 10-15 minutes, but the cook time depends on the food inside and the size of your container, so be sure to check your specific recipe.
Many people choose to use a steam canner, which looks like a Dutch oven. In a steam canner, food is placed on a rack at the bottom of the canner, over a bath of boiling water, which then produces steam that rises and envelopes the jars, killing the bacteria. Steam canners can cost anywhere from $20-$100+, so if you are looking for an easier water bath method, using a deep pot (with a lid) and a rack like a cake cooling rack or even stacking oven burners will have the same concept. Fully immerse jars in water about 1-2 inches, allowing the water to get to a rapid boil.
Heating in a water bath will kill off many microbes, but this does not kill dangerous botulism spores; so water baths should be reserved for foods high in acidity (4.6 pH or less). Botulism cannot be produced in high-acid environments.
High-acid foods recommended for the water bath method include:
Pickles and pickled foods
Jams, jellies, and pectins
Tomatoes and tomato juices
We recommend the Anchor canning jar with 2-piece lid for pickled delicacies or larger batches of tomato sauce and salsas, the 12 oz. ring-neck bottle for juices, sauces, or pectins, or our 8 oz. smooth sided jelly jar with high heat lid for jams or smaller batches.
Since higher-acidic food is more safely prepared in the steam canner, lower-acid foods (those with a pH of more than 4.6), like meats or vegetables should be pressure-cooked.
In pressure canning, containers are placed in around 2 to 3 inches of water, then heated to a temperature of at least 240 °F. Pressure canning can be dangerous if done improperly, so pressure canning requires more attention to detail than the steam method.
Two types of pressure canners are currently used: “dial gauge” canners which have pressure regulators for moderating the vent pipe and pressurize the canner, or “weighted gauge” canners, which are designed to rock or vibrate to maintain accurate pressure inside.
When prepping for pressure canning, make sure all vent pipes are clear and contain no deposits or built up food particles. The pressure canner must always be centered over the burner, and the burner/range must be at similar level. The burner heat must be maintained during the process, as too much heat can break the canner.
Pressure canners must be “vented” through its valve/pipe as the water for the jars preheats, about 10 minutes. After venting, the counterweight or gauge is placed over the vent pipe, and the canner begins to pressurize.
When the recommended pressure for the recipe has been reached, the cook time begins. Pressure canners must be fully depressurized after cooking as well, and it is recommended to wait 10-20 minutes after depressurization to open the lid and remove the jars.
Low-acid foods recommended for pressure canning include:
Meats & poultry
We recommend the 16 oz. mayo jar with a high heat lid for gourmet meats or larger vegetables like asparagus or carrots, the 16 oz. anchor canning jar for soups, or the 16 oz. embossed mason jar for gifting food or separating into smaller batches.
Once jars have been safely removed from either canning procedure and cooled via the suggested duration in the recipe, it is necessary to check if the jars have sealed correctly. Most home canners press down on the jar lids, which should feel secure and not wiggle or rattle when manipulated. Any jars with faulty seals should be refrigerated and consumed right away.
Jars of food should be labeled and stored out of direct light, somewhere cool and dry.
Canning is easy, quick, and fun. Read our Idea Center blog “Everything I Wish I Knew Before I Started Canning” for more tips and tricks to get you started!