Food > Consumer Centre > Specific Products / Risks 

VEGETABLES AND HERBS STORED IN OIL

Various foods are sometimes stored in oil to extend their shelf life and/or flavour the oil. Some examples include garlic, onions, sun-dried tomatoes, hot peppers, and mushrooms. These products are a popular home-prepared food item and in some cases, are also prepared commercially. Incidents of food-related illness in Canada and elsewhere in recent years have increased the concern over the safety of such foods, when stored in oil.

Why do these products present a health risk?

These products can present a health risk if stored improperly. If they contain Clostridium botulinum bacteria and are bottled and covered with oil, the conditions could be ripe for bacterial growth and toxin production. While refrigeration will slow down the growth of the bacteria, it may not prevent toxin production. Consuming products that contain these toxins can cause botulism, a potentially fatal food-related illness. This can happen without any evidence of spoilage such as "off" odour, taste or abnormal appearance.

What are the symptoms of botulism?

Symptoms may include dizziness, blurred or double vision, difficulty in swallowing, breathing and speaking, and progressive paralysis. The onset of symptoms takes approximately 12-36 hours and the duration may be 1-10 days although some symptoms may linger much longer. Botulism can be fatal and can cause permanent neurological damage in those who survive.

What should consumers do to protect themselves?

Home-prepared products stored in oil should be made using only fresh ingredients, and must be kept in the refrigerator and discarded after one week. Consumers who purchase home-prepared food products in oil from fairs, farmer’s markets or roadside stands or receive them as a gift should check when they were prepared and discard them if more than a week old.

What about commercially-prepared products?

Commercially-prepared products stored in oil that contain an acid (such as vinegar) or salt in their list of ingredients are generally considered to be safe. These products are processed using technology not commonly available to consumers. They should, however, be refrigerated after opening and between each use. If in doubt about the ingredients in a particular product, consumers can contact the manufacturer.

For more information:

The Canadian Food Inspection Agency continues to work with Health Canada and the food industry to contribute to the safe production of food products stored in oil. Food Safety fact sheets, including one on C. botulinum, are available on the Agency’s web site. You can also refer to Health Canada’s website at www.hc-sc.gc.ca.

P0074E-00
August 2000