Steam canners have been around for about 70 years and there is still a lot of controversy regarding this type of canning. So, I thought I would give you the University of California at Davis’ point of view on this.
Steam canners are not recommended because these practices do not prevent all risks of spoilage. Steam canners are not recommended because processing times for use with current models have not been adequately researched. Steam canners do not heat food in the same manner as a boiling water canner. Most manufacturer claims for steam canners is that process using less water, saves time and energy.
Today’s steam canner looks like an upside down boiling water canner. The base is a shallow pan with a rack that is covered with a high dome lid. The jars are placed on the canner’s base, a small amount of water in the base is brought to a boil and the dome fills with steam. The jars of food are heated by the steam surrounding them. However, steam canners do not heat the food in the jars the same way a boiling water canner does. A steam canner generally only gets to 170 degrees. You need to have a temperature of above 180 degrees to kill bad bacteria in your food. High acid foods, meaning tomatoes with added acid, salsas, fruit, pickles and applesauce would be under processed and therefore could spoil without you knowing it.
Most bacteria’s are tasteless, odorless and colorless. Most times we think we have the stomach flu, but generally it is food poisoning. Atmospheric Steam canners result in significantly lower product temperatures at the beginning and end of the process time when compared to water-bath canning.
Also, use of steam canners results in under processed food which means lots of spoilage. There is no approved conversion factor for using a steam canner versus a water-bath canner or boiling water canner.
They require the same amount of work — heat the jars, fill the jars with hot product, place your lids and bands in simmering water before placing them on the jar and place the entire thing back into the water bath canner. Bring your product up to a rolling boil and boil for the recommended time from your Ball canning book.
Grandpa always said, “Do it right the first time then to have to go back and do it again or throw the product away.”
TIP: Start going through your supplies and take a look at what you have left on your shelf that you canned from last year. It is always a good rule of thumb to eat what you have put up in a year. After a year the stability of the food contents start to lose their vitality or taste. Check jars, lids, and bands to get your supplies in order. Strawberries and asparagus are just around the corner for fresh strawberry jam and pickled asparagus.