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Better Canned Food is on the Way
by John Harmon
October 20, 2002

The canning season is almost over for another year and as any gardener knows the canned food from the summers garden is never quite as good as it was when fresh picked. Part of the problem is that once food is placed in jars or cans and heated to a high enough temperature to kill all the nasty bacteria some foods, especially vegetables, get soggy and loose flavor and nutrients.

The idea of canning first came from Napoleon who wanted to ensure his troops were well fed as they traveled from countryside to countryside conquering the known world. Many of the soldiers in Napoleon's army died from eating the crudely preserved food. In 1795 a French engineer named Nicolas Appert invented the canning process that we know today.

The canning industry produces about 200 billion cans worldwide every year. In Canada, roughly $2.5 billion worth of easy-open canned and preserved foods are shipped annually. In the 207 years since Appert patented the original canning process there have been major improvements in technology. For instance the instructions on a can of veal carried by a 19th century arctic exploration group read: "Cut around the top, near the outer edge with a chisel and hammer." You were fine as long as you remembered to pack your chisel!

Canning food remains among the most energy intensive of all food processing technologies. The contents of every one of the cans are heated under steam pressure to a temperature of 121 degrees centigrade for a minimum of three minutes. The home canning process takes longer in a pressure canner or water bath to reach a high enough temperature. The heat is needed to prevent the growth of Clostridium botulinum bacteria that can cause botulism in humans. The problem is that sterilization requires vast amounts of energy and the production of that energy creates a significant volume of greenhouse gases.

In the world of Kyoto and climate change many leaders and researchers are looking hard for ways to improve the planet, while reducing the damage that food production is doing to the environment. Led by Dr. Michèle Marcotte, a team of Agriculture and Agri-Food Canada (AAFC) scientists at the department's Food Research & Development Center, in Saint-Hyacinthe, Quebec may have developed a process that will make an important contribution.

The new process is based on replacing the extreme high temperature method currently used in the canning industry, with a low temperature pasteurization system. As a result, energy use during the canning process is cut by 30 per cent; greenhouse gas emissions are reduced by 17 per cent. The process also involves acidifying foods to a pH of less than 4.6. The acidification makes it possible to reduce the subsequent pasteurization temperature, while ensuring product safety. If you have done some home canning you may remember that "low acid" foods are the ones that can be processed in a water bath instead of a pressure canner.

The benefits of the new canning process don't end there. By reducing the food's exposure to high temperatures, the AAFC method also improves its nutritional quality by preserving the vitamins and anti-oxidants that would be destroyed by the heat used in conventional canning systems. Food retains its flavor and has a crunchier texture and brighter color. Some of the foods being studied include sauces, gravies and soups. Your canned vegetable soup may soon be almost as good as Mom's homemade stuff.

Dr. Marcotte's group is one year into a three-year study of the new system, using a pilot canning plant at the Saint-Hyacinthe center. The plan is that they will pass along their results to food processors at the end of the project, but based on the findings to date, one company has already adopted the new technology.

Once the project is completed and the information put to use there may be better canned food available for sale and a better process for gardeners to use at home to try and preserve that garden fresh taste to enjoy over the long dark.

For more information on the history of canned food check out

John Harmon owns and operates Tropicals North. Write to John at The Real Dirt, c\o 211 Wood St., Whitehorse, YT., Y1A 2E4 or e-mail

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