Sugar and safety: Those are the two big concerns of home cooks when it comes to canning.
When people even think about making their own jams or pickles, they experience what I call “recipe shock” about the amount of sugar required. (For example, a traditional strawberry jam recipe calls for five cups of mashed fruit and seven cups of sugar.) Many people these days want to limit sugar, either because they are diabetic or for weight control.
When it comes to food safety, canning scares many people because of one threat: botulism. They are too afraid to even try canning their own food for fear of making their loved ones sick. If you understand the science behind safe canning practices, you will know how to eliminate that risk and can without fear.
I heard these concerns again and again these last several months at events for my first cookbook, “Pickles & Preserves: A Savor the South Cookbook.” With strawberry season in full swing and peach season not far off, here are answers to your most common canning questions with an assist from fellow canning cookbook authors, food scientists and home economists.
“It’s important to recognize that jams and jelly are candy. You are essentially candying the fruit to preserve it,” explained Sherri Brooks Vinton, author of the best-selling “Put ’em Up” canning books and the recently released, “Put ’em Up Preserving Answer Book: 399 Solutions to Your Questions.”
Without the correct amount of sugar, Vinton explains, the jam may not set, will not have that bright, glossy color and ideal texture or last as long once opened.
Look for low-sugar, no-sugar pectins by Ball or Sure-Jell, which can be used to make jam with lower quantities of sugar, Splenda or honey.
Vinton and Marisa McClellan, author of the popular Food In Jars blog and two preserving books, recommend a product called Pomona’s Universal Pectin, a commercial pectin packaged for home use. Available online and at Earth Fare, Williams-Sonoma and Whole Foods stores, Pomona’s comes with two packets: one of pectin and another of calcium that is mixed with water before it is added to the fruit. Because the calcium helps the jam set, recipes using Pomona’s can use less sugar.
Vinton has two books with recipes that call for Pomona’s: “Put ’em Up,” and “Put ’em Up Fruit.” In addition, Pomona’s makers recently published a cookbook, “Preserving With Pomona’s Pectin,” by Allison Carroll Duffy.
Vinton advises against using artificial sweeteners, such as aspartame and sucralose, because they become bitter when cooked and create an off flavor.
Let’s cover some basics to explain the science. There are two types of canning: boiling water bath canning, which is used to process high-acid foods, such as jams, jellies, preserves and pickles; and pressure canning, which is required for low-acid fruits and vegetables, meats, poultry and soups.
With high-acid foods, processing jars in a boiling water bath, which reaches temperatures of 212 degrees, is all that is needed to kill molds, yeasts and bacteria. With low-acid foods, pressure canning is required to reach a temperature of 240 degrees, the level at which harmful bacteria and botulism spores can be killed.
The key to safe canning is following professionally tested recipes, such as those from the National Center for Home Food Preservation and from authors you trust. “People are very afraid of preserving their own food,” Vinton says. “They don’t have to be. Just follow the recipe.”
Ben Chapman, a food scientist at N.C. State University, explains that processing the jars in a boiling water bath helps kill microbes in the food, vent out oxygen containing microbes and remove as much air as possible from the jars to create a good seal – all essential for producing a safe product. Without that processing, he explains, microbes may be able to grow.
This is what I tell people who ask about open-kettle canning and using paraffin: “Just because your grandmother did it doesn’t make it safe. Your grandparents rode around in cars without seat belts. We know more know about food safety than they did and we should be smart enough to use that knowledge.”