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UC Master Food Preservers of Central Sierra

Preserve It! Series!

Formerly the UC Master Food Preserver of El Dorado County's Preserve It Poster series, this is a collection of answers to frequently asked canning, preservation, and food safety questions. 

If you don't find your answer here, reach out to your local Cooperative Extension Master Food Preservers. 

In El Dorado County, California, the best way to do that is with the Ask a Master Food Preserver link. 

Ask a Master Food Preserver

 

UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Is it okay to wash canning jars in the dishwasher?

May 7, 2026
Washing and sterilizing are two different things. Is it okay to wash canning jars in the dishwasher? Sure, it’s a convenient option, especially if you have a lot of jars to clean, and it’s a good way to keep the jars hot until they’re ready to be filled and go into the canner. (And just a reminder that…
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Is it Safe to Can Previously Frozen Produce?

May 14, 2026
Safety and quality depend on what you have in the freezer.If you’ve got an excess of produce that you don’t have time to process, can you store it in the freezer to can later? Yes, sometimes. The freezing process breaks down the cell structure of produce, which changes the density of the food. For this…
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Is Reusing Commercial Product Jars Wise?

May 7, 2026
Commercial product jars are not designed to be repurposed for home canning. Is it possible to reuse mayonnaise and other similar commercial product jars for home canning? Some people have done so with some success. But even though it’s technically possible, it’s really not advisable. Here’s why…
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: It's Not Recommended to Can White Peaches

April 30, 2026
Choose only yellow peaches and nectarines for canning Food safety research is happening all the time, with results sometimes dictating changes in home canning recommendations. It’s for this reason that we always advise following recent recipes published from reputable sources. One such fairly…
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Jar Breakage is Shocking, but Avoidable

May 7, 2026
Canning Basics: Thermal shock and how to prevent it. There are many reasons that canning jars can break during the canning process.  One common cause for jar breakage is thermal shock, caused by a temperature differential between hot and cold. The break is characterized by a crack that runs around…
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Just Say "No" to Eating Raw Batter & Dough

May 6, 2026
Be safe when handling raw flour Flour is, generally speaking, a raw agricultural product which has not undergone any treatment to kill pathogenic bacteria – such as E. coli and Salmonella – that can cause foodborne illness.  Several disease outbreaks associated with flour and flour products …
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Know Where to Find Helpful Preserving Advice

April 30, 2026
Safe Preserving Resources  There are many books and websites covering food preserving, but unfortunately not all of them provide good advice. Some sources provide processes or recipes that are downright dangerous. So where do you turn for research-based, reliable information? Or to find safe information…
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Know Your Elevation When Canning

May 14, 2026
Make your altitude adjustments. Did you know that at altitudes over 1,000 feet above sea level, you need to make adjustments to your canning procedures? When boiling water or steam canning, processing times need to be lengthened. When pressure canning, pressure needs to be increased. Why? Because as…
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UC Master Food Preservers of Central Sierra: Article

Preserve it! Series: Leftover Lifetimes - Time and Temps for Keeping Food Safe

May 6, 2026
When in doubt, throw it out! Leftovers can be a lifesaver when you need a meal in a hurry, but unfortunately they don’t last forever. Or even a long time. And no, turning leftovers into another kind of leftover does not extend the life of the original food. Keeping food at proper temperatures and…
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