A friend of mine asked me if brine had to be hot when poured over raw packed pickles or could he make it earlier, let it cool, and then pour it over the vegetables before putting them in a hot water bath. I honestly hadn't thought about it and thought maybe the liquid should be hot so that the jars don't shatter when they hit the hot water or maybe there's a different reason. Now I want to know.
The pickling liquid should be brought to boil then poured into the preheated jars that are filled with the product. Yes, one reason is to keep the jars hot so they do not shatter because of lack of heat when placed in the boiling water canner. Another reason is the process. If the liquid is not hot it will take longer for the center of the jars to reach the correct heat and create a good vacuum at the end of the process. Also, the heating of the liquid is to stop any bacteria or enzymes.
For additional information, visit
www.uaf.edu/ces or nchfp.uga.edu