From Ronda’s Front Porch To Yours
Have you been wanting to learn about canning and don’t know where to start? You will first want to start with a research-based recipe that has been proven to be safe to eat after canning. Our friends at Michigan State University Extension walk us through the science of canning and why it is important getting them from a good source to prevent food borne illness.
What does “research-based” or “research-tested” really mean? Imagine researchers in white lab coats working over hot stoves, filling jar after jar with test recipe jams and salsas. It may sound funny, but canning recipes really are developed in lab-like situations set up like a home kitchen with researchers at the helm.
The product needs to taste delicious but also be safe to eat.
When a new recipe is being developed, one of the main traits being studied is the pH of the product. pH is a measure of the acidity or alkalinity of a substance. Lemons, tomatoes and berries are considered acid foods and have a pH of less than 4.6 (the scale goes from 1 to 14, 7 being neutral). Foods like squash, beans and meat are low acid foods with a pH greater than 4.6.
The reason pH is important is because of the bacteria Clostridium botulinum, which is a common microorganism that produces a deadly toxin known as botulism.
In high acid foods, the C. botulinum spores will not germinate and thus cannot produce the toxin. These foods can be canned in boiling water through a process called hot water bath canning.
Low acid foods, however, need a different type of processing due to the possibility of C. botulinum growth. The spores are destroyed at temperatures of 240 degrees Fahrenheit or above for specific periods of time.
Since that temperature is above the boiling point (212 F at sea level), pressure canning is the method needed to reduce the likelihood of botulism toxin. Some foods like tomatoes are close to the borderline pH of 4.6, so acid is added to them (in the form of lemon juice or citric acid) so they can safely be canned in boiling water.
What does any of this have to do with using your own recipe, or a recipe passed down from your great grandmother or a recipe you find online?
Many people have created canning recipes and even published them in popular books throughout the world, without ever measuring the pH of their product.
Botulism can’t be seen, smelled or tasted, so the best way to prevent food poisoning is to only use recipes that have been rigorously tested by reliable sources and have a known pH.
In addition to pH, the processing time is extremely important to the safety of the finished product.
Processing times for canning are based on the density of the product and how long it takes to heat that product to the proper temperature throughout the entire jar. Home canners most likely don’t have access to the high-tech equipment to perform those measurements and thus don’t know with any certainty that their own recipe has been thoroughly processed.
Family and community health extension agents in District 2 Texas A&M Agri-Life Extension is having a series of online canning classes beginning August 4.
The series will contain an introduction to canning and equipment used, water bath basics and pressure canning basics. Registration is online at https://preservingyourharvestonline.eventbrite.com. Cost is $17.55 for all three classes.
For more information about the class you can contact the Scurry County Extension office at 573-5423.
For recipes and more resources on food preservation visit us on our Facebook page at Scurry County Texas A&M AgriLife Extension.
Source: Michigan State University Extension, Lisa Treiber