Why you should think twice before trying home canning

There are safer ways to preserve summer produce, according to U of A experts who offer four alternatives.

As backyard gardens ripen and store shelves bloom with fresh in-season produce, it's natural to want to shelve that summer goodness with the traditional method of home canning.

But there are other, safer ways to preserve garden bounty long-term, according to University of Alberta food microbiologist Michael Gänzle.

Unless home canning is done under the supervision of seasoned cooks with proper boiling pressure equipment, it should be avoided by newbies, he advised.

"The days when mother knew how to do it are over. If you don't can food safely, there's a risk of killing yourself or someone else," he said.

The main threat is botulism, a disease caused by deadly, hard-to-detect bacteria that doesn't change the colour, taste or odour of food. Through the spread of the bacteria's airborne spores, "one can that has gone wrong can contain enough toxin to kill all Albertans," Gänzle said.

"It's like a chemistry experiment," added U of A registered dietitian Sabina Valentine. "Home canning has to be done very accurately to remove all the air, to make sure the food is heated enough, to have a tight seal. Botulism can't be killed without proper canning pressure."

Freezing or drying foods carries less risk in terms of food safety because they prevent pathogenic bacteria from growing and producing toxins. Because of the cooking required, home canning doesn't preserve food's taste or texture any better, Gänzle noted. Canning also eliminates water-soluble vitamins B and C from food.

There is some vitamin and mineral loss with all preservation methods, Valentine noted, but "fruits and vegetables will still have a great deal of nutrients along with fibre, phytochemicals and water."

Try these options:

Eating fresh

Eat your harvest fresh-picked from the garden to get the most from it.

"There's no loss of nutritional value because of storage or transportation as there is for retail produce," Valentine noted.

Rinse off the dirt and then enjoy raw veggies like onions in salads or cooked into stews and soups. Sturdy produce like carrots, beets, onions and potatoes can go into cold storage-a cool, dark spot that is 10 to 15 C-to extend their shelf life.


Herbs like dill and sage can be air-dried to flavour warm winter dishes, while some fruit and vegetables can be dried as healthy snacks. Crabapples, peaches, apples, carrots, celery, corn, green beans, potatoes and tomatoes can be sliced, spread on baking sheets and then dried in a low-temperature oven or a food dehydrator.


Succulent herbs like basil, chives and mint are best preserved through freezing. Berries, rhubarb and assorted vegetables like peas, carrots, zucchini and tomatoes (for sauce) can also be frozen for later use. While there is more nutrient loss than with drying, the food still retains most of its value.

"It's a great way to get our daily servings of fruit and vegetables year-round," Valentine said. Use these chilling timelines for best results.


A form of pickling, fermentation occurs when starches and sugars in the food are converted into lactic acid by the bacteria lactobacilli. It's what gives fermented foods like sauerkraut their tangy smell and taste. If done properly, the process poses no food safety hazards, Gänzle noted. It involves tightly packing vegetables into jars of salted water. Good choices are carrots, string beans and pickling cucumbers. Cabbage has enough water of its own to only require salt for the fermentation to happen.


If you do choose to can produce and are doing it for the first time, have someone experienced in the kitchen with you. Follow these safety tips from the Government of Canada and the USDA to ensure the correct temperature is used, Gänzle advised. Procedures for canning differ between high-acid foods like fruit or pickles, and low-acid foods like meat, poultry, seafood, milk or spaghetti sauce that can grow botulism spores if improperly canned.

Jam or jelly are lower-risk canning choices because the cooking process kills bacteria, including any that may be living in the jar. Turning the hot contents upside down in the sealed jar will also kill anything growing on the lid, he noted.

Using recipes low in salt and sugar makes home-canned foods healthier without posing any food safety risk, Valentine said. "Salt and sugar are added for taste, not preservation."

Salt content can be lowered by adding vinegar, with hot peppers, herbs or garlic added for flavour. Sugar helps hold the colour and texture of jam, so cutting back by using a low-sugar gelatin or artificial sweeteners will result in a softer, more spreadable texture and darker colour, she noted.

"To get the best results possible with low-sugar recipes, use high-quality fruit that isn't overripe. To prevent discoloration, crush a vitamin C tablet, dissolve it in water and pour it over the fruit before canning it."