Tuesday, September 18, 2007

Waterbath Canner verses Pressure Canner

The most frequently asked questions from our readers are “Do I really need to use a pressure canner for this recipe?” or “Can’t I use a waterbath canner for this recipe?” So, let’s address the differences between the two.

A waterbath canner processes canned goods submersed in boiling water. Water boils at 212F or 100C at sea level. A pressure canner, at 11 pounds of pressure, processes foods at a higher pressure and reaches a temperature of 240F or 115C at sea level. This represents a 15 percent increase in the processing temperature!

Some foods are more acidic and some are less acidic or non-acidic. We can typically taste acidic foods on the sides of the tongue, not to be confused with bitter tastes on the back of the tongue. Sweets are tasted with the tip of the tongue. You can test this by tasting consecutive spoonfuls of lemon juice (acidic,) tonic water (bitter,) and a sugar cube (sweet,) and then noting the area of the tongue that becomes sensitive upon tasting each one.

Common acidic foods are citrus fruits, apples, berries tomatoes and peaches. At the opposite end of the spectrum, low-acid foods include meats and vegetables with the exception of some peppers. Although we can taste these on our tongue, a more accurate measurement of a food’s pH, or level of acidity can be made using pH strips or a pH meter. Both can be found at our canning supply store.

In canning, the magic number for determining high-acid verses low-acid foods is 4.6. Foods with a pH of 4.6 or below are considered high in acid and are generally safe for processing using a waterbath canner. Certain bacteria exist in low-acid foods, with a pH above 4.6, that cannot be eliminated at 212 degrees Fahrenheit. Low-acid foods must be processed at the higher temperature of 240 degrees Fahrenheit. Please note there are certain dense foods that should never be processed at home such as pesto.

If you intend to process a lot of low-acid foods, we highly recommend an investment in a good pressure canner. We prefer the All-American pressure canners, which can be quite expensive. You might start making hints that one would make a great holiday or birthday gift! Waterbath canners and pressure canners may be found at our canning supply store.

More information about high-acid and low-acid foods can be found in our five dollar technical guide available at the CanningUSA.com.

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