Use hot pack method to minimize separation when canning tomatoes

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By Grace Angotti

This past week, 12 people interested in learning food preservation methods attended our very successful food preservation workshop at the Carroll County Extension office. Local extension volunteer and food processor Bobby Giles of Carrollton was a great help in helping me teach the workshop. Thank you so much, Bobby! We gave them hands-on experience in canning green beans, strawberry jam and freezing sweet corn and concentrated on the USDA-approved techniques and information.
One of the questions that I had during the workshop was how to prevent tomatoes and tomato juice and other products from rising to the top instead of being uniformly distributed in the jars after processing.  
The following is excellent information shared with the University of Kentucky by the University of Illinois Extension http://web.extension.illinois.edu/state on why home canned tomato products separate. This should help other readers as you are canning this summer.  
Why do home-canned tomato products separate?
Do you ever wonder why the tomatoes and tomato juice that you can at home separates?           
Home-canned tomato products separate because of a natural enzyme action. There is an enzyme in raw tomatoes that acts to break down the pectin that holds tomato cells together.  As soon as tomatoes are chopped or crushed and the enzyme is exposed to air, it starts to work breaking down the pectin. This causes the solids and liquids in the finished product to separate.
You can prevent this separation by using heat to inactivate the enzyme before it has a chance to start working.  Commercial tomato juice manufacturers do this by flash heating their tomatoes nearly to boiling in seconds, using equipment that is not available to home canners.
The best way to minimize separation in your home-canned tomato products is to use the hot pack method. For tomato juice or sauce, heat some of the tomatoes in the recipe quickly to boiling while crushing. Then continue to slowly add and crush freshly cut tomato quarters, making sure that the mixture boils constantly as you add the remaining tomatoes. Simmer for five minutes after you add all the tomato pieces, before juicing. For canning whole tomatoes or cut tomatoes, heat them prior to packing in jars.
In the raw pack method, the enzyme has a longer period of time to act before the heat of the canning process inactivates it.
Remember that tomatoes today are lower in acid than they used to be. Therefore, lemon juice or vinegar needs to be added prior to canning to acidify them. It is generally recommended for a better product to use a pressure canner to can tomatoes today due to this lower acid. The amount of acidity in the tomatoes will determine if you should use the boiling water bath method or a pressure canner.
For more information on home canning tomatoes and tomato products, or other produce, contact me. I also have the new, recently revised University of Kentucky Cooperative Extension food preservation publications on canning and freezing fruits and vegetables, pickles and relishes, jams and jellies and meats, poultry and fish available if you wish copies. There is no cost for any of these.
Another excellent reference on food preservation is the National Center for Food Preservation at http://nchfp.uga.edu/how/store/store_home_canned.html.

“Christmas in July” is Tomorrow
The Carroll County Extension Homemakers invite interested residents to attend their “Christmas in July” workshop tomorrow, July 25, from 9 a.m. until 2 p.m. at the Extension office. A variety of Christmas crafts will be taught by Extension Homemaker members with special food, music and decorations adding to the holiday atmosphere. If you wish, stop by the Extension office today for more information on crafts being taught.

Grace Angotti is Carroll Co. Extension agent for family and consumer sciences. Call her at (502) 732-7030 or send e-mail to gangotti@uky.edu.