During the COVID-19 pandemic, we have been receiving an increase in inquiries related to home food preservation. According to the U.S. Food and Drug Administration, there are no widespread disruptions in the food supply chain.
The empty shelves in grocery stores are mostly because of a tremendous increase in demand, and consumers storing an overabundance of products, rather than a lack of capacity in the food supply to produce, process and deliver food. Despite these reassurances, it can be unsettling to see empty shelves, and more consumers are interested in preserving food at home.
Whether you are a pro or just getting started, it is important to review the basics of safe canning. Many people want to be able to preserve their favorite recipes, or foods often found in stores.
However, safe canning is dependent on several factors, including the acidity of the food (pH), the amount of water available in the food to support growth of microorganisms (water activity), and the amount of time the food needs to be processed (heat penetration), to ensure the coldest spot in a jar of food has received adequate heat treatment to destroy microorganisms.
Commercially canned food has undergone rigorous testing to determine how the food will need to be processed to ensure it is safe. Unfortunately for the home canner, this means that only well-researched recipes and processes are safe for canning, and these recipes and processes must be followed exactly. If a well-researched recipe and process is not available for your favorite shelf-stable food, you can always freeze the food in a food-safe container.
Below are some tips from an article published in the Daily News in August 2018 designed to help the home canner avoid botulism. Clostridium botulinum, the microorganism that produces the botulinum toxin, can grow and produce the toxin in canned food where the pH is above 4.6, and the water activity is above 0.86. This is most often an issue with home canned foods that contain vegetables and meat, and have not been properly processed. These low-acid foods must be processed using a pressure canner, unless a proper amount of acid has been added to ensure the pH is well below 4.6.
To avoid the risk of botulism:
Only use recipes which have been tested for safety. Contact your extension office for more information on which sources are considered to be safe.
Use the appropriate canner for the recipe and follow all specified processing times and recipes exactly.
Never fill hot food into the jar and let seal without processing. You must use the appropriate canner/canning method to process the food safely.-- Do not open, smell, touch, or eat any food from jars that are damaged, leaking, swollen, squirts liquid or foam when opened, or looks or smells bad. If you are ever unsure whether food is safe, throw it away.
Boil home-processed low acid foods, like tomato sauces, meats, soups and vegetables, for 10 minutes in a saucepan before serving even if there is no sign of spoilage.
Are you new to canning? Your local extension office can provide you with safe recipes and processes to get you started. Most people prefer to start with water bath canning, as it tends to be a less complicated process.
Before you start you will need some supplies including appropriate sized canning jars with 2-piece lids (refer to the recipe), a water bath canner or a large enough pot which will allow covering the jars completely with 2 inches of water (for water bath canning), a jar lifter, kitchen towels, and items specified in the recipe. A wide-mouth funnel and ladle will make filling jars easier.
Many of these supplies can be found at your local hardware or grocery store. If you are pressure canning, you will need a pressure canner that is in good working condition. Canners with pressure gauges need to have the gauge checked for accuracy every year. If you are buying a new pressure canner, it may be best to purchase a weighted gauge canner as these do not have gauges that need to be tested for accuracy. You will want to make sure the gasket on the lid is flexible and not damaged, and the vent port is clean. Always fully read the manufacturer’s instructions for your canner before using.
Be sure to follow the directions in the recipe exactly, so your hard work will result in a delicious and safe product. You will need to know your elevation, as different elevations will require different processing times and pressure, if pressure canning.
Canning food is a great way to preserve food, and provide you with some reassurance. Your local extension office can help you get started, and provide you with safe recipes, so don’t hesitate giving them a call.
Dr. Stephanie Smith is an assistant professor and statewide consumer food specialist for Washington State University Extension. She can be reached at email@example.com.