Why is a hot pack recommended for large fruits, like apples, peaches and pears?
Raw packed fruits often float because they contain air. As air escapes from the jars, liquid is carried with it. Bringing fruits to boiling in a pan before packing them into jars drives air out of the plant tissue. As a result, there will be fewer problems with fruits floating to the top of the jar. There will be less liquid lost from the jars. There will be fewer problems with fruits turning brown near the top of the jar. And, more food will fit in the jars since heating shrinks plant tissue; however, hot food should be packed fairly loosely.
Barbara Willenberg, Nutritional Sciences, University of Missouri-Columbia
Last update: Tuesday, May 05, 2009