WESTPORT — If you've flipped through all your seed catalogs and completed your orders, take a pressure-canning class to make 2012's garden harvest last and last.

The Cornell Cooperative Extension in Essex County offers a class on how to preserve low-acid vegetables safely on Jan. 22 at the Westport office.

"In the past a lot of times people have told us, they were watching their mothers do it and it would blow up," said Eileen Longware, nutrition educator and master food preserver. She teaches the class with Judith P. French, administrative assistant/master food preservation educator.

"People have a fear of pressure canning," Longware said. "Some have never done it since they watched their mothers."

Technological advances in pressure canners have changed everything.

"We're holding the class to alleviate the fear of people who have had these past experiences and teach them new requirements of the USDA in regards to canning," she said. "Most vegetables are low acid and should be canned in a pressure canner."

Though many people process green beans with a boiling-water bath, pressure canning is the safest method.

"Food is heated to a higher degree (240 degree Fahrenheit), and it is processed and held at that temperature for a longer time than boiling-water bath canning."

Raw and cooked vegetables and meat can be processed with a pressure canner.

"There's a bit of an advantage to precooking them. You can pack more into your jar."

The foodstuff is placed in clean and dry canning jars secured with metal lids and rings, tighten to just beyond finger tight. The jars are placed in a canner, and the canner lid is locked on. Canners vary. Some have dial gauges. Others have weighted gauges. No matter the canner configuration, altitude can impact the canning process and adjustments must be made.

Longware and French prefer the weighted canner, which has a weight gauge that is placed over a cone of steam escaping from the vent.

"We look for a cone of steam to come out for 10 minutes, a good steady cone of stream," Longware said. "Whatever your recipe says, 10 pounds or 15 pounds of pressure, you put your weight over the cone of steam. You start timing your canner when you have a jiggle. It (weight) moves pack and forth. A weighted gauge starts to jiggle or rock. It's according to your manufacturer's directions."

Gauges can rock back and forth or move rapidly.

"After the canner time is finished, you turn off the heat and let the whole canner depressurize," Longware said. "That might take as long as 30 or 40 minutes, even longer. It depends on your canner and again the instructions in your manufacturer's book. After the canner is depressurized, remove the weight from the vent where the steam was coming out, you wait 10 more minutes. Only then can you unfasten the lid to the canner."

Low-acid foods include fish, chicken, beef and venison.

"Most every vegetable except for squash and pumpkin, unless you cube. Fruit is generally high acid. It can be canned in a boiling-water canner. It's a similar process but you're not bringing up to the temperature and not processing it as long as food in a pressure canner."

People should only use recipes later than 1994.

"Anything prior, you need to check out and from a reliable source that would have been tested that food is safe when it is processed at that temperature for that amount of time. We recommend the Ball canning books or So Easy to Preserve from another cooperative extension."

Jars should be stored in a cool, dry dark place and not in bright light for no longer than a year.

"It's very important to label your jars as well," Longware said. "I know from my own experience, you forget what you've done."

While gardens rest beneath the snow, it's a boon to open up a can of carrots and green beans.

"The reason you pressure can rather than a boiling-water bath is because of (a) really scary toxin, clostridium botulinum," French said. "It causes botulism (food poisoning). Pressure canning will kill it. Boiling-water bath canning doesn't. Low-acid foods are prone to that toxin. To ensure you kill it when you're processing your food, you use a pressure canner."

Low-acid foods harbor clostridium botulinum, which loves warm room temperatures and wet environments. Boiling-water bath canners are great for high acid fruits, jams and jellies.

"That's the main point we try to get across," French said. "Green beans in boiling-water baths, we would like to stop. It's dangerous. That's the point of our workshops."

The Cooperative Extension's goal is to teach people how to preserve local food while having a higher-quality product. French said she was a poster child for doing everything old-fashioned and wrong.

"The food is different," she said. "It's genetically modified. Our tomatoes are not the tomatoes your grandmother had. The acid level is different. The quality is different. When they made their jam, they put their wax on top. Wax is not made the same anymore. Skip the wax. The acid level of the food and how the food is produced have changed. It's not the same."

French encourages people's interest in canning.

"The more you learn, the more you want to do."

Grandma's pickles or Aunt Ida's apricot jam recipes do not have to be cast aside entirely.

"We can compare it with modern recommendations to make sure it's still safe to make and consume," French said.

Email Robin Caudell at: rcaudell@pressrepublican.com