Posted in Putting Food By
Headspace
A certain amount of headspace must be allowed in all canned foods. This is the space in the jar between the underside of the lid and the top of the food or its liquid. Some foods, especially those that are starchy, swell more in the jars than others, and, therefore, require more headspace. Pressure canned foods also expand more and require more headspace.
If too little headspace is allowed, the food may expand and bubble from the jar during processing. The bubbling food may leave a deposit on the rim of the jar or the seal of the lid and prevent the jar from properly sealing.
If too much headspace is allowed, the food at the top is likely to discolor in storage because of the headspace will contain more residual oxygen.
Headspace is measured from the top of the jar to just where is begins to balloon out.
1/4-inch headspace (just below the first glass thread)
1/2-inch headspace (just below the middle glass thread)
1-inch headspace (just below the finish or last larger thread)
1-1/4-inch headspace (mid-way on shoulder)
1-1/2-inch headspace (just below the shoulder)
Lids
The common self-sealing lid consists of a round, flat metal disc held in place by a metal screw band during processing. The flat lid is crimpled around its bottom edge to form a trough, which is filled with a colored gasket compound. When jars are processed, the lid gasket softens and flows slightly to cover the jar-sealing surface yet allow air to escape from the jar. The gasket then forms an airtight seal as the jar cools. Gaskets in unused lids work well for three to five years following manufacture instructions.
Buy only the quantity of lids you will use in a year. To ensure a good seal, carefully follow directions. Examine all metal lids carefully. Do not use old, dented, deformed lids or lids with gaps or other defects in the sealing gasket. While I buy used canning jars, I only use new lids and rings.
After you remove air bubbles by inserting a flat plastic spatula between the food and the jar, slowly turn the jar and move spatula up and down to make sure all air has escaped. Adjust the headspace and then clean the jar rim with a dampened paper towel.
Place the lid, gasket down, onto the cleaned, jar-sealing surface. Then fit the metal screw band (I call these rings) over the flat lid. Screw until you begin to feel resistance and then make snug. DO NOT over tighten your lids. This is like getting your water the right temperature to make your yeast work.....not to hot and not to cold. It is the same way with your lid tightening.
--If rings are too loose, liquid may escape from jars during processing, and seals may fail.
--If rings are too right, air cannot vent during processing and food will discolor during storage. Over-tightening also may cause lids to buckle and jars to break, especially with raw-packed, pressure-processed food.
As jars cool, the contents in the jar contract, pulling the self-sealing lid firmly against the jar to form a high vacuum.
Screw bands are not needed on stored jars. I remove my lids only after jars are completely cooled. I then clean and dry them thoroughly before putting them away. If you leave them on, they may become difficult to remove, often rust, and may not work properly again. They may also conceal the loss of the seal in the jar.
I will continue this topic next Wednesday.
Peggy and her husband John, along with 6 children (ranging from young adult through four years) live along the Appalachian mountains range in Pa. Peggy enjoys mentoring women in home things. She has just introduced a new monthly e-zine entitled, "The Simple Woman's Gazette" coming out in early March. You can find a FREE Sample and subscription information at this link
You can find her blog at http://www.homesteadblogger.com/TheSimpleWoman/
Come on over and say Hi!
You can also find Peggy's articles and devotionals archived at Home Made Simplicity and lots of basic canning information as well as encouragement at her food preserving blog, The Simple Woman's Cannery.
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http://www.homesteadblogger.com/HomeMadeSimplicity/ (Home Things)
http://www.homesteadblogger.com/asimplewomanscannery/ (Canning Basics)
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