Canning is an inexpensive way to keep your recent purchase from rotting in the vegetable drawer. In many cases, fruits and vegetables that are canned immediately after harvest can be as nutritious or even more so than fresh, off-season produce.
In a nutshell, canning is a method of keeping food fresh and requiring glass jars and heat. It processes food at high temperatures, removes all air, and then vacuum-seals the food in jars to prevent spoilage.
These important steps kill contaminants, making it possible to store canned food for long periods of time. Fresh produce contains water, so it is perishable, and contaminants, including microorganisms, food enzymes, oxygen, and loss of moisture can wreak havoc on canned foods if procedures are not followed properly.
The next step is to decide what you are going to be able to. You can choose ingredients to pack raw or hot.
- Raw packaging method : The jars are filled with raw foods like chopped carrots and then covered with boiling liquid.
- Hot packaging method : This involves filling jars with pre-cooked and hot food instead of raw. This would include jam or cooked fruits and vegetables, which are then covered with boiling liquid. In the case of fruits, the liquid should be sugar syrup.
Finally, let’s talk about how to do canning. There are two main methods of home canning: water bath canning and pressure canning . Both methods work well for a variety of foods, so choose the best method for you.
Canned in a water bath
Canning food in a water bath can be done using a pot that you already have on hand, as long as you can put six to eight jars inside and it is at least 8 centimeters higher than the jars.
The pot should fit over a stove and the lid should be snug and hold in place over boiling water. The combination of time and temperature with water bath packaging destroys contaminants while creating a vacuum seal.
Foods that work best for water bath canning
Choose high-acid foods like tomatoes, fruit, jam, gravy, pickles, and hot sauce.
What you will need
- Can for water bath or a large pot with lid and canning grid.
- Glass jars, lids and rings.
- Jar lifter to remove the jars from the packaging machine.
- Kitchen utensils: wooden spoon, ladle, long tongs, funnel, spatula.
- Clean handles and tea towels.
- Food for the can.
How to do it
- Wash the canning jars, lids, and rings in hot soapy water or in the dishwasher, and then rinse them well.
- Fill the pot with water at least halfway and place it on the fire with the grid placed inside. Turn the heat to high and let it boil; then, reduce heat to low (83ºC) and cover the pot.
- Place empty jars on the canning rack in the hot water.
- Prepare your high acid foods to put them in the jars by rinsing them thoroughly under running water.
- Using a jar lifter, remove a preheated jar. Fill the jar with prepared food. For foods like jam, use a pitcher funnel. For products like fruits or vegetables, pack the food in the jar tightly but not the tritures. Then add boiling water or liquid to cover the food and leave an inch of clearance.
- Use a spatula to release the air trapped in the jar.
- Clean the edge and top of the jar to remove any food.
- Center the lid on the jar so that the sealing compound is directly on the edge of the jar. Put the lid on and close it firmly, but stop turning when you feel resistance.
- Put the jar back in the pot and repeat until the jars are full and back in the pot. The water should cover the jars by at least 4 centimeters.
- Put the lid back on the pot and bring it to a boil. Set a timer for the required number of minutes based on the item you’re canning.
- Once complete, turn off the heat, remove the lid, and allow the jars to remain in the water for 5 minutes.
- Remove the jars and place them on a towel, leaving them to rest for 12 to 24 hours. As the jars cool, you may hear a hollow sound.
- Once cooled, make sure the lids are sealed and slightly curved down. If you press the center of the lid, it should not move.
- Label the jars with the type of food in each and the canning date. Then store them in a cool, dry, dark place. For best results, open them in a year, although they should last up to 18 months.
Canned under pressure
Pressure packaging requires the purchase of a steam pressure canner, which can heat food to 240 to 250 degrees Fahrenheit, the recommended temperature so low-acid foods can be sterilized to avoid food poisoning.
This combination of time and temperature destroys foodborne bacteria and creates a vacuum seal to prevent spoilage. A steam pressure canner has a lid that locks in place, allowing steam to build up inside and reach the right temperature, similar to a pressure cooker.
Foods that work best for pressure canning
These foods include low-acid vegetables and chili.
This method is the same as the water bath packaging method detailed above. However, instead of the large pot and water, follow the manufacturer’s instructions that come with the pressure canner.
How to avoid canned food poisoning?
Great care must be taken when canning any food. It is vital to follow instructions and processing methods to prevent spoilage and growth of Clostridium botulinum , which causes botulism, a deadly form of food poisoning.
Harmful bacteria can multiply quickly given the right environment for growth, which includes low-acid, moist foods, temperature in the danger zone (40 degrees to 120 degrees Fahrenheit), and less than 2 percent oxygen.
Before serving canned food at home, it is important to inspect the jar for any damage. The caps should be tight and still pressed in the center, indicating a proper seal.
Some signs, such as the following, may indicate that the food is contaminated:
- The lid is swollen.
- There are streaks of dry food from the top of that jar
- There is mold in the jar.
- Bubbles are rising in the jar.
- Liquid or food comes out of the bottle.
- The color of the food does not look natural in any way.
- The liquid is cloudy.
If any of these signs are present, do not open or eat the contents of that jar. A properly sealed bottle should “pop” and “buzz” as you remove the cap. There should be no unpleasant odors, gases, signs of fermentation or mold.