Low-Temperature Pasteurization Treatment

The “Low-Temperature Pasteurization Treatment” is a low and slow method for processing home canned jars of pickles.

Respected home-canning author Linda Ziedrich writes,

Many people hesitate to subject their pickles to a lot of heat for fear it will ruin the texture of the pickled foods. A boiling water bath can definitely soften cucumbers and some other vegetables. For this reason a scientist at the University of California developed the low-temperature pasteurization method for home picklers. By this method you don’t boil your jars, you just immerse them in 180 to 185 F (82 to 85 C) water for 30 minutes.”  ^[1]Ziedrich, Linda. The Joy of Pickling. Boston, Massachusetts: The Harvard Common Press. 2009. Page 21.

The procedure was  added to the “accepted canon” of USDA procedures in 1988.  ^[2] “1988 low temperature pasterurization process introduced for some pickles was added to USDA complete guide. Andress, Elizabeth. “History, Science and Current Practice in Home Food Preservation.” Webinar. 27 February 2013. Accessed January 2015 at https://nchfp.uga.edu/multimedia/video/nchfp.wmv 

The National Center for Home Food Preservation (NCHFP) gives further details:

Low-temperature pasteurization treatment: The following treatment results in a better product texture but must be carefully managed to avoid possible spoilage. Place jars in a canner filled half way with warm (120° to 140°F / 50 to 60 C) water. Then, add hot water to a level 1 inch (3 cm) above jars. Heat the water enough to maintain 180° to 185°F (82 to 85 C)  water temperature for 30 minutes. Check with a candy or jelly thermometer to be certain that the water temperature is at least 180°F (82 C) during the entire 30 minutes. Temperatures higher than 185°F (85 C) may cause unnecessary softening of pickles.”  ^[3] National Center for Home Food Preservation. Preparing and Canning Fermented and Pickled Foods: Low-Temperature Pasteurization Treatment . Accessed June 2015

 

Only use with tested recipes that allow it

There’s a catch though: this process cannot be used for everything. You only use with the approved recipes that say they are made to use this process.

The NCHFP says, “Caution: Use only when recipe indicates.”  ^[4] National Center for Home Food Preservation. Preparing and Canning Fermented and Pickled Foods: Low-Temperature Pasteurization Treatment . Accessed June 2015

Ziedrich says that goes for her recipes, too:  “[My] recipe instructions indicate when this method can be used.”   ^[5]Ziedrich. Page 21.

What would appear to be confusing is that on page 1-29 of its 2015 guide, the USDA says, “To further improve pickle firmness, you may process cucumber pickles for 30 minutes in water at 180°F (82 C) . This process also prevents spoilage, but the water temperature should not fall below 180°F (82 C) . Use a candy or jelly thermometer to check the water temperature.”  ^[6] United States Department of Agriculture (USDA). Complete guide to home canning. Agriculture information bulletin No. 539. 2015.  Page 1-29

Perhaps the wording is poor, but it almost would appear to open the door to any cucumber pickle recipe for the low-temperature process. One would need to ask them via the NCHFP for clarification but in the meantime, there’s lots of other caution about using it only with recipes that call for it.

Oregon State University Service cautions that the low temperature pasteurization method should not be used with reduced-sodium pickles: “Do not use low temperature pasteurization method for processing pickles when making reduced-sodium pickles.”  ^[7] Food Safety & Preservation: Low Salt Pickles. Oregon State Extension. SP 50-533, Revised February 2013. Accessed June 2015 at https://extension.oregonstate.edu/fch/sites/default/files/documents/sp_50_533_lowsaltpickles.pdf

They do not say why.

Making altitude adjustments when using low temperature pasteurization treatment

When using the low-temperature pasteurization method, no altitude adjustment is needed, either in terms of time or temperature. The reason is that you are controlling and monitoring the temperature of the water with the aid of a thermometer, so you are going to reach and hold it between the target range at whatever altitude you are at.

Iowa State University Extension says,

Do not change the processing time.” ^[8] Francis, Sarah. Canning: Pickles. Iowa State University Extension. PM 1368. September 2014. Page 3.

Some home canners say that the low temperature pasteurization method is particularly important for those who live at high altitudes. They say that a 10 minute boiling water bath at sea level can end up being 25 minutes for people at high altitudes, after adjustments, and few if any pickles will survive being boiled that long.

Miscellaneous notes

The low temperature pasteurization method can be used with pint or quart size jars, apparently, when your tested recipe indicates.  ^[9] Viz the recipes in: Paul, Lynn and Alice Bautz. Canning Pickles and Sauerkraut. Montana State University Extension. MT199607 HR Reviewed 3/2006. Accessed March 2015 at https://store.msuextension.org/publications/HomeHealthandFamily/MT199607HR.pdf

The low temperature pasteurization method might be where an electric water bath canner (such as those made by Ball, Weck or Fowlers Vacola) with a thermostat would come in handy, so you don’t have to stand by the stove for 30 minutes and watch a thermometer like a hawk.

At the end of the 30 minutes, you immediately remove the jars from the canner — you don’t give them the traditional 5 minute rest period in the canner. “Immediately remove jars from the canner at the end of processing time. Put jars on a rack or cloth so air can move freely around them.”  ^[10] Pickling Vegetables. Pacific Northwest Extension. PNW 355. June 2008. Page 5.

 

Further reading

National Center for Home Food Preservation. Preparing and Canning Fermented and Pickled Foods and Preparing and Canning Fermented and Pickled Foods: Low-Temperature Pasteurization Treatment