The Oregon State University Extension Service issued the following information in response to a question the office received.
Q: I received a home preserved gift for the holidays. How do I know it’s safe to eat?
A: What a great question! Home preserved food gifts are common over the holidays, and they are given with thoughtfulness and care. However, it is certainly important to consider the safety of these home preserved foods as you feed you and your loved ones. This is especially true since many people used their time at home during COVID-19 shutdowns to learn to preserve foods. While there are many people that are doing everything correctly, there are also people that may not know or understand that there can be dangerous risks.
The biggest potential risk from home-preserved foods is a deadly toxin produced by a specific bacterium: clostridium botulinum. If conditions are right, and this bacterium grows in your food, it will produce a toxin that can cause paralysis and death because you can’t breathe. This is a real risk for some improperly preserved food products. It is absolutely critical that home-preserved foods be processed using a research based tested recipe and processing time to prevent this toxin from being formed in home-preserved foods.
What home-preserved food gifts are potentially dangerous? Any “low acid” home canned food — vegetables, mushrooms, meats (red, white, fish), soups and melons and some tropical fruits. These food products can all support the growth of clostridium botulinum. Therefore, to be safe they must have been processed in a pressure canner using the appropriate weight and processing time (adjusted for altitude). Weights and processing times are dependent on the type of food as well as the size of the jar. There are not any recommended recipes or processing conditions for home canned products that are stored in mylar “retort” pouches – therefore, these would not be considered safe.
How about canned acidified or pickled foods — tomatoes, salsas, pickles, etc.? The correct amount and type of acid (bottled lemon juice, vinegar (5 percent acid), or citric acid) must have been added to the recipe in order to prevent the growth of clostridium botulinum in the product. Most acidified foods, including pickled vegetables, are processed in a water bath canner to prevent spoilage. Following tested recipe directions and using the correct amount of acid listed in the recipe is critical to the safety of these products. Only make ingredient substitutions if the recipe resource allows it. Tomatoes that were canned with the skins, even if they were pureed, are not safe to eat.
Vacuum-sealed foods stored at room temperature: If there is enough moisture and a low amount of acid, then clostridium botulinum can grow in vacuum-sealed packages. Adequately dried products (fruits, vegetables, nuts) are safe to store at room temperature, however, smoked meats/fish should always be refrigerated. If storing longer than two weeks, freeze it. Jerky must have been dried properly before packaging to be safe in vacuum-sealed containers. Zippy-style bags or food-safe storage containers work well for dried foods and there is no risk of botulism.
Jars that are not sealed or noticing mold when you open the container: Do not consume food from any jar where the lid was not sealed after 24 hours or became unsealed in storage. Also, if you notice mold on the top of the food when you open it, do not eat it. As mold grows, it changes the pH of the food, which can change the safety of the product. Jams, jellies and spreads sealed with wax are at risk for mold. If you can see mold, we now know that an invisible, extensive root system exists that can cause digestive upsets. Sealing with paraffin wax is no longer recommended as a safe food preservation practice.
Be cautious of “trendy” canned foods. It takes time and resources to scientifically test new food preservation methods. Just because you might be able to buy a similar product at the store does not mean that it can be made equally safe at home. There are no safe methods for canning products like pesto or flavored oils. Canned bread is also an unsafe product.
What home preserved food gifts are almost always safe?
• Canned Fruit products — halves, slices, jams, jellies, preserves, pie filling, and applesauce. The majority of fruits are high in acid with a pH below 4.6 (the critical point for clostridium botulinum growth). Therefore, single fruit products and jams, jellies and pie fillings are generally safe when directions from reliable resources are followed. There are a few exceptions — melons, mangoes, white peaches/nectarines, elderberries — that have a higher pH and are not safe to can but are safely preserved by drying or freezing.
• Baked goods (bread, cookies, etc.), candied or roasted nuts, candy. These products have low moisture. Enjoy these with no fear!
How do I ask my friend/family member if the food is safe without offending them? Obviously, everyone assumes that they are preserving food correctly. However, we know that many people don’t understand the risks and there is a lot of incorrect, unsafe information on the internet. You really need to know where they got their recipe or information about processing the food. You could ask: “This looks really great, where did you find the recipe?” “I’ve wanted to learn to can, where did you find the instructions?” “Wow! This looks amazing! It must have taken you a long time to make it.”
People that can foods tend to really enjoy it and want to talk about it, so they will likely give you a lot of information. If they give you an answer that includes a university extension website or publication, a current publication or website from Ball/Kerr brands (a company that has worked closely with the National Center for Home Food Preservation) or that they followed the instructions on a commercial pectin, jerky or sausage package, then you can be confident that they processed the product properly.
Products like canned tuna take 100 minutes to process, so if they shrug it off as being easy or fast, then be skeptical. If your guests let you know they are bringing a home preserved treat for the dinner, do a little homework before they arrive. You can compare their information with recipes in the OSU Extension publications, the National Center for Home Food Preservation web page or Ball/Kerr’s.
If you still aren’t sure, call the statewide hotline: 1-800-364-7319.