Canning 101: What to know before preserving your summer fruit crop
In a previous column, I discussed how to preserve your fruit crop by freezing or dehydrating it. Since I am also a certified master food preserver, I thought I would use this column to discuss canning. I’ve seen all sorts of terrible (and dangerous) advice on the internet regarding canning techniques and I feel that I should provide some guidance on this topic.
There are three approved methods for home canning: hot water bath, steam, and pressure canning. High-acid foods can be processed by hot water bath or steam canning. Low-acid foods must be processed by pressure canning.
Most fruit can be considered high-acid for canning purposes. There are some exceptions to this, however. Yellow peaches are high-acid and can be canned in a hot water bath. White peaches, which are milder in taste, are not acidic enough to be safely canned in a hot water bath. Personally, I prefer to save my peaches by peeling, slicing, tossing with Fruit Fresh, vacuum sealing and freezing. This preserves the texture of the fruit, which makes it suitable for pies, crisps, cobblers, and other uses where you don’t want your fruit to be mushy.
Tomatoes are technically a fruit but are not acidic enough to be considered safe for water bath canning unless some form of acid is added. More recently developed and tested recipes will call for the addition of acid (vinegar, lemon juice, or citric acid). Recipes from older canning books that do not call for the addition of acid are no longer considered safe.
If you have a big tomato crop and wish to preserve it, I recommend trying a salsa or sauce recipe from a reliable source such as the National Center for Home Food Preservation, The Ball Blue Book (recent editions), or any Master Food Preserver website (which will be associated with a university/cooperative extension). My previous attempts at canning whole tomatoes have been disappointing, so I stick with sauces and salsas. If you have your own recipe, you can always make it for fresh eating or freezing. When canning, only use tested recipes and follow them exactly to ensure a safe product.
There’s lots of dreadful advice on the internet, but when it comes to food preservation that advice can be downright dangerous. It’s nice to give your friends and family something unique and homemade, but if you give them food poisoning your gift may be remembered with less fondness than you had hoped.
“Open kettle” canning is an unsafe practice that appears on the internet frequently. This involves putting hot product into a hot jar, screwing the lid on, and inverting the jar to seal it. This is risky because the contents of the jar have not been completely sterilized through processing. Although the jar may seal, the contents could still harbor enough bacteria to cause spoilage.
The National Center for Home Food Preservation website has a very good FAQ section that addresses many unsafe canning practices with clear explanations as to why they are unsafe. Check it out at https://nchfp.uga.edu/
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; 949-809-9760; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-683-6491 ext. 231; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu