Is it safe to guess on a processing time for home canned food?

Food preservation needs to be treated as an exact science, using research based recipes, precise measurements of ingredients, clean work environments and exact timing when it comes to processing procedures.

Produce is beginning to ripen and home canners are planning what they will preserve for the months ahead. It is also the time that Extension experts begin to receive calls from consumers asking about processing times; can they be estimated if they can’t find a recipe, or perhaps substitute a time, using a similar recipe to what they have canned before?

To respond to the title of this article, the answer is no, food preservation needs to be treated as an exact science, using research based recipes, precise measurements of ingredients, clean work environments and exact timing when it comes to the processing procedures. If you were to guess at a process time for canning, there would be the chance of running a risk of underprocessing food, possibly leading to food poisoning and/or product loss due to spoilage.

The National Center for Home Food Preservation says that research based recipes for canning will include process times that have been determined by or based on results of laboratory testing. The exact time and temperature combinations of tested canning processes are needed to assure the destruction of microorganisms that may be present in the filled jars. It is possible that you have used unsafe canning practices before and never had an issue, but it only takes one batch of food with destructive microorganisms to ruin your streak of luck. The chances of problems occurring if you are canning low acid foods are higher, and the consequences could be devastating to you and your family.

Sometimes it is obvious to see microorganisms just by looking (molds growing on the surface of jelly), but many others are invisible to the eye, such as pathogenic bacteria which causes food poisoning. Many different types of mold, yeast and bacteria may be found on food. The conditions of moisture, acidity, oxygen levels and temperatures provide perfect environments for these pathogens to grow and possibly become toxic.

The process times stated in research based home canning recipes have been developed to deliver enough heat to destroy microorganisms of concern in high acid and low acid foods. Researchers have taken into consideration characteristics such as consistency, pH level (the acidity of the produce), size of food pieces, size and shape of jars and solid to liquid ratio; these all influence the ability of heat to move through and thoroughly penetrate the entire contents of a filled jar. This is why it is so important to use proper canning methods with a pressure canner or water bath canner and follow recommended processing times.

Michigan State University Extension recommends using research based recipes for canning; the following sources would qualify as research based:

By following a current research based recipe, fresh produce, proper processing times, a correct canning method, (pressure canner for low acid foods, water bath canner for high acid foods) in a clean environment, your home canned foods will be delicious foods to enjoy throughout the year.

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