Other advantages: better flavor, color, texture and taste, and possibly better nutrition, Hunsaker added. "You can take into account health concerns like hypertension or diabetes and adjust the sodium or sugar."

However, would-be canners should realize that if the food turns out to be inedible because it wasn't processed right, all that money and effort goes to waste.

In a survey by the University of Georgia in 2005, about one in five households home-canned foods. Of those, 30.5 percent said they altered recommended canning procedures. Open-kettle canning, where hot food is poured in jars and left to seal on their own, was practiced by 44 percent of them. And 32 percent reported jars that didn't seal properly.

"That is bad news to an extension agent," said Sara Oldroyd of the Salt Lake County USU Extension.

Updated safety guidelines

The USDA has updated its safety guidelines over the years, stating that jams and jellies need time in a boiling-water bath. As the popularity of salsa has risen, so has the amount of time that tomato products need to be processed — now 95 minutes for cold-packed quarts for Wasatch Front altitudes.

Years ago, you might have sealed jams and jellies with paraffin wax. Today's guidelines call for metal lids and screw-on bands to seal the jars against any bacteria or mold.

This year's salmonella outbreak cast suspicion on tomatoes, jalapenos and serrano peppers. But pathogens are killed when heated to boiling-water temperatures, said Oldroyd.

"In fact, that is why we do boiling-water baths," she said. "Botulism is the bacteria we are wary of in home canning, because it can survive in anaerobic conditions and at temperatures above boiling. So either we have to add acid or pressure can."

Oldroyd wouldn't recommend buying tomatoes when there's an outbreak, and the USDA advises against it. "But now that the outbreak has passed, tomatoes can be bought and processed again. However, freezing doesn't kill E. coli, and neither does refrigeration. If you decide to freeze your mother's salsa recipe, make sure the tomatoes and chiles are from a safe source."

How canning works

The premise of home canning is to interrupt the natural decay that happens to food from existing enzymes, mold, yeast and bacteria. You place food in canning jars, top them with a lid and screw cap. To "process" them, the jars are heated in a boiling-water bath canner, a steam canner or a pressure canner, at a high temperature long enough to destroy the microorganisms.

When the jars cool, they vent excess air and form a vacuum seal on the lid.

Processing times (and whether you should water bath cans or pressure-can food) are determined by: