Some canners and canning methods should not be used by consumers. Those methods include:

Steam canners –– The steam canner was designed as a means to process foods using steam without the aid of pressure. The manufacturer claims this process uses less water, saves time and energy, and recommends identical processing times as those required for boiling–water bath treatments.

Studies have concluded that:

Atmospheric steam canners result in significantly lower product temperatures and that the use of steam canners would result in under processing and considerable spoilage.

Solar canning –– The heat generated from captured sunlight is not a reliable method to process acid foods and should never be used to can low-acid foods.

Oven canning –– The oven canning method involves placing jars in an oven and heating. In oven canning, product temperatures never exceed the boiling point because the jars are not covered. It is, therefore, not safe to use for products that require temperatures higher than 212 degrees.

Because this process fails to destroy the spores of Clostridium botulinum, it can cause the food to become toxic. Also, canning jars are not designed for intense heat and may explode.

Open kettle canning –– The open-kettle method involves placing hot food in jars and sealing with no further heat treatment. The amount of heat applied may not be sufficient to destroy bacteria and the product may spoil quickly or cause illness.

Microwave processing –– Microwave oven cannot be used for home canning. Microwaved food reaches 212 degrees, but heating is not uniform. There is also a danger of explosion of the jars as food is being removed from the oven.

Dishwasher processing –– Processing canned foods in a dishwasher cycle is dangerous. The temperature of the water during the cycle is far below that required to kill harmful micro-oganisms. Thus the product will be underprocessed and unsafe to eat.

Angela Treadaway is an extension agent for Shelby County. She can be reached by calling 410-3696.