Home canning still an effective way to preserve fresh food

As autumn approaches, many gardeners are ready to preserve the fruits of their summer labor by canning.

Whether you grow your own produce or support a local market, canning is an excellent way to save money and preserve the nutritional quality of fruits and vegetables while they are at their peak, said Luke LaBorde, associate professor of food science in Penn State's College of Agricultural Sciences. “The principal advantage of canning home-grown produce is that it can be a lot cheaper than buying fruits and vegetables," he said. "You're harvesting them at their optimum flavor and maturity, so you get a better product."

Fruits and vegetables begin losing vitamins as soon as they are harvested, LaBorde explained. Nearly half of their vitamins may be lost within a few days.

For centuries, canning has been an effective way to preserve produce and retain nutritional value, but even with today’s improved sanitation and food-safety awareness, there are considerable risks in the process if it is not executed properly. Even the most experienced canners run the risk of food-borne illness, so it is important to use the highest-quality produce and to follow procedures carefully.

Canning preserves food by removing oxygen and destroying enzymes to prevent the growth of harmful mold, bacteria and yeast. Improper sealing or the presence of air bubbles considerably raise the risk of harmful bacteria growth.

The most serious threat for canners is the bacterium Clostridium botulinum. Growth of this bacterium in canned foods may cause botulism, a deadly form of food poisoning. "Immersing canning jars and lids in boiling water does not destroy the bacterial spores that cause botulism, which are much more heat-resistant than cells," warned LaBorde, who says canners should follow approved guidelines carefully to ensure that canned goods stay safe and delicious all through the winter.

To prevent threats of illness and contamination, canned foods should pass this test:

— Full jars should have proper headspace between the food and the lid.

— Liquids should just cover solids.

— Jars should be free of air bubbles.

— Produce should be free of imperfections as well as stems, cores and seeds.

— Jars should be properly sealed.

— Food should have a characteristic, uniform color.

The Food Safety Web site maintained by Penn State’s Department of Food Science, http://foodsafety.cas.psu.edu, hosts numerous resources to help home canners follow food-safety guidelines in their own kitchens. The Web site provides access to USDA preservation guides, food-safety tips from University researchers, extension educators and government authorities, and links leading to more than 1,200 reviewed food-safety Web sites, including those of federal agencies such as the Food and Drug Administration, the Centers for Disease Control and the Environmental Protection Agency.

The site also connects users with Pennsylvania canning newsletters, discussion boards, charts of boiling points and process times, sites for canning equipment and even an online "Jeopardy" preservation game. Users can access a link to courses and workshops on food safety offered through Penn State's Food Science Department.

"Canning can help you save money, get the most out of your garden and have nutritional produce all winter long," LaBorde said. "Penn State’s Food Safety Web site provides information that makes it easier for new and seasoned canners alike to safely enjoy the process and product for long after the summer has gone."