FREEPORT, Ill. — Home canning is a cost-saving way to preserve food grown in a garden.
“Canning is a process where food is placed in jars and heated to a high enough temperature to destroy harmful organisms,” said Diane Reinhold, University of Illinois Extension nutrition and wellness educator for Jo Daviess, Stephenson and Winnebago counties.
Preserving food starts in the garden, Reinhold said, during a Fill Your Pantry: Canning at Home webinar.
“Soil may contain botulinum spores, so it is important to brush off the soil before you bring produce indoors,” she said. “Use food-grade containers and clean the produce thoroughly just before you’re ready to use it.”
All canners should use good personal hygiene.
“Wash your hands because dirt can harbor harmful microorganisms and if you have a cut make sure you cover it,” Reinhold said. “The Centers for Disease Control and Prevention estimates 48 million Americans each year have a foodborne-related illness, 128,000 are hospitalized and 3,000 die and all of those are very preventable.”
Two types of canning can be used to preserve food — boiling water bath or pressure canning.
“Boiling water bath canning is used for high acid foods at shorter processing time and pressure canning is for low acidic foods and requires longer processing time,” Reinhold said.
“High acidic foods have a pH value of 4.6 or less and examples are pickles, strawberries, blackberries, apples and plums,” she said. “Low acidic foods have a pH value higher than 4.6 and they include corn, carrots and squash.”
Since the pH of tomatoes falls on the borderline, Reinhold said, acid must be added during the canning process.
“You can add one teaspoon of bottled lemon juice,” she said. “It has to be bottled lemon juice because it has a standardized pH value and we don’t know the pH value of fresh lemons.”
Additional options include one-quarter teaspoon of citric acid or two tablespoons of vinegar.
“I like to add the citric acid since it is fairly inexpensive,” Reinhold said.
Reinhold stressed the importance of using a scientifically-tested recipe.
“Recipes in the So Easy to Preserve book are all scientifically tested,” Reinhold said.
“Use Mason-type canning jars with a threaded top and they will be either regular or wide mouth,” she said. “These jars come in different sizes — half pint, pint or quart. Use the half-gallon jars only for grape or apple juice.”
The two-piece self-sealing lids have a metal screw band and a metal lid with a sealing component.
“Only use the self-sealing lids once,” Reinhold said.
Sterilizing the jars is not the same as sanitizing, Reinhold noted.
“You need to sterilize the jars after you wash them by putting them in a canner of boiling water for 10 minutes,” she said.
Reinhold likes to use a wide mouth funnel when filling jars to reduce spillage.
“Follow the recipe and make sure you leave enough headspace above the food and below the lid,” she said.
“If there is too little headspace, the food can bubble up during processing, come out of the jar and interfere with proper sealing,” she said. “If there is too much headspace, there could be extra air and the jar might not seal properly.”
Once the jars are filled, Reinhold said, use a plastic knife to free the bubbles.
“Secure the lid until it is finger tight,” she said. “Don’t go too tight because the lids can buckle or the jars might break.”
Each recipe will be different for the processing time and the processing time will vary depending on the food being processed.
“Always follow the directions carefully,” Reinhold said. “Never under process because that can result in food spoilage and over processing can result in undesirable texture of the food.”
It will take from 20 to 30 minutes for the water to start boiling for the boiling water canning process.
“There should be one to two inches of water covering the tops of the jars and you might be surprised how much water evaporates,” Reinhold said.
“Start timing after the water reaches a full rolling boil,” she said. “After the processing time is complete, turn off the heat, remove the lid and wait five minutes.”
A pressure canner requires two to three inches of water.
“The water will turn to steam and vent out during the process,” Reinhold said. “Never put jars in the canner without a rack because the jars can break.”
It is important to watch the pressure canner to make sure it maintains the pressure throughout the time stated in the recipe.
“When done processing, turn off the heat, allow the canner to de-pressurize and wait 10 minutes before opening the lid,” Reinhold said.
After removing the jars, Reinhold advises putting them on a cooling rack to allow the air to get under the jars.
“Let jars sit undisturbed for 12 to 24 hours and then test the seals,” she said. “If your jars don’t seal, you have the option to reprocess them which must be done within 24 hours, but you’re going to end up with a mushier product.”
Jars of canned food should be stored in a cool, dry, dark location, at a temperature of 50 to 70 degrees.
“Do not store them above 95 degrees and if there is too much humidity, the lids can corrode,” Reinhold said. “For best quality of product use the jars within one year.”