MSU Extension

Canning has been making a comeback in popularity the last few years. One just has to look at the aisles in the stores and see all of the different gadgets related to food preservation. But when do some of these gadgets become more than something the consumer needs to have? I was in a major kitchen store recently and saw a name brand pressure canner sitting on the shelf next to an electric canning device. As an Extension Educator, many questions have been asked in classes I teach, via e-mail, and over the phone about pressure canners and other cooking appliances.

Let’s begin with some simple facts. There is a difference between a pressure canner used for canning and a pressure cooker used to cook roasts and chicken dinners on the stove top. Often the two are talked about in the same conversation, and I want to be clear, they are not the same. A pressure canner is designed to can low acid foods (vegetables, meat, poultry, fish and wild game) they are designed to hold canning jars (upright) and process at a temperature higher than a water bath canner. A pressure cooker or pressure saucepan may not maintain adequate pressure; they heat and cool too quickly, which may not destroy microorganisms that can cause foodborne illness in home canned food. A pressure canner has either a dial or weighted gauge, and may hold multiple jars of canned food depending on its size. Pressure cookers are smaller and they may or may not have a way to regulate the pressure. The pressure cookers do not come with pressure gauges, and they cannot be safely used to process home canned foods.

There are also appliances that promote themselves as “multi-cookers” with buttons on their front panels for canning or steam canning. Be sure to research carefully before purchasing one of these appliances. The United States Department of Agriculture (USDA) and the National Center for Home Food Preservation are telling us there could be a risk to botulism food poisoning in under-processed foods, because the proper amount of heat is not delivered to all parts of the food in the jars during the time it’s processed in these appliances.

Major reasons multi-cookers cannot be recommended for home food preservation:

• No USDA thermal process work has been done with jars inside an electric pressure cooker of any kind. Thermal process canning work shows the temperatures in the jars to the temperature inside the canner for the whole processing time.
• Temperature matters, not pressure when processing in a pressure canner. Many of these multi-cooker appliances have not been tested to determine if they are processing correctly, producing proper interior pressure, and uniform temperatures, nor is there an option to adjust pressure readings at higher altitudes.
• Another concern is the safety of the final product, is the temperature in the canner able to maintain at minimum temperature throughout the entire process time? If there are power surges or drops in electricity that could cause the canner to drop temperature how would the operator know this had occurred?
• Research based process times for canning foods rely on a combination of heat from the time the canner is coming to pressure, the actual process time, and the early stages of cooling the canner and jars. Once the heat has been turned off, the heat is high enough to continue to kill bacteria in a traditional pressure canner. This all factors into the time for the canning process. There is no way to determine the actual cooling recommendations with the multi cookers. If the cooling process happens too quickly, in a small unit, the food could be under processed.

This article about electric canners does not apply to the products developed by Ball Corporation for acid foods. Their appliances are suitable for processing high acid foods; make sure you follow their directions.

Michigan State University Extension encourages all home canners to follow current research tested recipes for ingredients and correct processing times. To learn more about safe canning practices contact a Food Safety Extension Educator at MSU Extension or take our on-line Food Preservation Course.