Northwest Arkansas Democrat-Gazette
Acidity of most fruits makes preserving them as a spread a cinch.
Acidity of most fruits makes preserving them as a spread a cinch
Many cooks have a bit of trepidation about canning. And with good cause — canned low-acid foods such as vegetables, meats and some tomatoes can harbor harmful organisms if not processed properly. But high-acid foods, including most fruits, pose little risk.
Almost all bacteria, yeast and molds will die when exposed to temperatures between 175 degrees and 210 degrees. The exception is botulinum toxin. Food-borne botulism is rare, but it can be fatal. Which leads us back to the fear that shrouds home canning. While botulinum toxin can survive high heat and little oxygen, it cannot grow below a pH of 4.6.
The good news is most fruits used for jam and jelly making are high acid.
Jordan Champagne’s book It
Starts With Fruit, includes a handy chart that lists the pH of common fruits as well as pectin levels. We’ll get to pectin in a minute.
Lemons, limes, cranberries and pomegranates sit at the most acidic end of the scale with a pH of 2.0-3.0; next are apples, stone fruits, bush and bramble berries, rhubarb, oranges, grapefruit and quinces with pH of 3.0-4.0; then we enter the gray area of bananas, pineapples, papayas, some figs, pears, some tomatoes and some grapes which fall between 4.0-4.6. Some tomatoes and some figs, along with Asian pears and persimmons fall in the 4.6-5.0 range. Melons, mangoes and dates are even less acidic. Water, at 7.0, is the neutral point.
Vegetables, peppers, legumes, herbs, mushrooms, olives, grains, meat and dairy fall between 4.6 and 7.5, making them unsuitable for boiling water bath canning. These foods must be pressure canned.
But jam is virtually risk-free. By starting with high acid fruit, adding sugar (a natural preservative), and sometimes lemon juice (more acid) and cooking the mixture to the gelling stage — 220 degrees — and then refrigerating or canning the jam in a boiling water bath canner there’s very little that can go wrong.
Pectin is naturally present in almost all fruits to varying degrees. Under-ripe fruit has more pectin than ripe fruit, and some fruits such as apples, quince, cranberries, grapes and lemon are quite high in pectin. At the lower end are peaches, blueberries, figs, pears and strawberries.
Most jam recipes call for some pectin, but cooked jams do not require the addition of pectin. They simply require careful cooking to ensure proper gelling. However, low-sugar and freezer (uncooked)
jams, do require the addition of pectin.
Commercial pectins are not interchangeable, but the fruit used in most recipes is. Be sure to use the specific kind of pectin called for in the recipe.
For example, we made Raspberry-Rose Freezer Jam which is no-cook and made with freezer pectin. While this recipe will not work with regular pectin, you could swap the raspberries for blueberries, strawberries, grapes or even plums or peaches (add a little lemon juice) and the recipe will still work.
For further reading: m The New Homemade Kitchen: 250 Recipes and Ideas for Reinventing the Art of Preserving, Canning, Fermenting, Dehydrating and More by Joseph Shuldiner
m It Starts With Fruit: Simple Techniques and Delicious Recipes for Jams, Marmalades, Preserves by Jordan Champagne
m Preservation Society Home Preserves: 100 Modern Recipes by Camilla Wynne
m Ball Canning Back to Basics: A Foolproof Guide to Canning Jams, Jellies, Pickles and More by Ball Canning Test Kitchen
m Preserving the Season: 90 Delicious Recipes for Jams, Jellies, Preserves, Chutneys, Pickles, Curds, Condiments, Canning & Dishes Using Them by Mary Tregellas. (I should note this book does not follow modern food safety practices. However, it does contain some useful information.)
For detailed, step-by-step instructions on preparing a boiling water canner, canning jars and lids, visit arkansasonline.com/613canning.
With the exception of the apricot jam, all of the following recipes are prepared using fresh fruit. We used Ball brand powdered pectin in the following recipes.