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Wednesday, August 2, 2017
It's food preservation season! With all the work it takes to preserve garden foods, make sure you are off to successful canning season; get your pressure canner gauge tested.
Reason for testing; pressure canning is for low-acid foods. Low-acid foods include red meats, fish, poultry, and all vegetables, except for most tomatoes. Low-acid foods can support the production of the deadly botulism toxin if they are not processed properly in a pressure canner. A pressure canner needs to reach a temperature of 242° F or above to kill and destroy the spores that produce the botulism toxin. Clostridium botulinum bacteria are on most fresh food surfaces, but because they grow only in the absence of air, they are harmless on fresh foods. The conditions which favor the germination of these spores are low acid foods (like vegetables and meats) in anaerobic environments (without oxygen), such as sealed canning jars. Clostridium botulinum is a very deadly toxin or poison, commonly known as botulism. Botulism is the most deadly food poisoning.
Home-canned vegetables are the most common cause of botulism outbreaks in the United States. From 1996 to 2014, there were 210 outbreaks of foodborne botulism reported to CDC. Of the 145 outbreaks that were caused by home-prepared foods, 43 outbreaks, or 30%, were from home-canned vegetables. These outbreaks often occur because home canners did not follow canning instructions, did not use pressure canners, ignored signs of food spoilage, or were unaware of the risk of botulism from improperly preserving vegetables. https://www.cdc.gov/features/homecanning/. Only use current with up-to-date, scientifically tested guidelines like the USDA National Center for Home Food Preservation, http://nchfp.uga.edu/publications/publications_usda.html. Don't use outdated publications or cookbooks, even if they were handed down to you from trusted family cooks.
There are two types of pressure canners; dial gauge and weighted gauge. Weighted pressure canners release any pressure above the desired amount of pressure and the weight will rock gently and make frequent jiggling noise to indicate the correct pressure is maintained. Reference the manufacturer's instructions to use a particular weighted gauge properly. Weighted gauges do not require testing. Dial gauges operate by indicating pounds of pressure on the dial while you control the pressure using the stove burner knob to adjust the heat up and down. Dial gauges require annual testing for accuracy
By testing your dial gauge annually, you know if the canner will process high or low. If a dial gauge reads high, it can result in under-processing resulting in unsafe food. At low, the food will be over-processed, which affects quality. Pressure adjustments can be made if the gauge reads up to 2 pounds high or low. With a difference of more than 2 pounds, gauge replacement is required. In addition, replace gauges that are cracked or the glass covering is missing. Only annual testing will determine if a gauge is safe to use.
How do you test your gauge?
- Check with your local University of Illinois Extension office. In Bureau, LaSalle, Marshall and Putnam counties, free pressure canner testing clinics are scheduled at offices and during farmers markets. For more information, call 815-224-0889 or access our calendar online;http://web.extension.illinois.edu/units/calendar.cfm?UnitID=470
- Presto also tests gauges at no charge; the address is listed below. Presto can only test gauges from the following brands:
- Magic Seal
- Maid of Honor