(USDA Complete Guide to Home Canning, 2015)

Before jars and cans can be processed they have to be filled through either the raw (cold) pack or hot pack method.

(Benson, 1917)

Raw/Cold Pack

Raw-packing is the practice of filling jars tightly with freshly prepared, but unheated food. Such foods, especially fruit, will float in the jars. The entrapped air in and around the food may cause discoloration within 2 to 3 months of storage. Raw-packing is more suitable for vegetables processed in a pressure canner.

--United States Department of Agriculture. (2015). USDA complete guide to home canning, 2015 revision: Principles of home canning. Retrieved from http://nchfp.uga.edu/publications/publications_usda.html

(Tomoatoes Packing, 1943)

Hot Pack

Hot-packing is the practice of heating freshly prepared food to boiling, simmering it 2 to 5 minutes, and promptly filling jars loosely with the boiled food. Whether food has been hot-packed or raw-packed, the juice, syrup, or water to be added to the foods should also be heated to boiling before adding it to the jars. This practice helps to remove air from food tissues, shrinks food, helps keep the food from floating in the jars, increases vacuum in sealed jars, and improves shelf life. Preshrinking food permits filling more food into each jar.

 

Hot-packing is the best way to remove air and is the preferred pack style for foods processed in a boiling-water canner. At first, the color of hot-packed foods may appear no better than that of raw-packed foods, but within a short storage period, both color and flavor of hot-packed foods will be superior.

 

--United States Department of Agriculture. (2015). USDA complete guide to home canning, 2015 revision: Principles of home canning. Retrieved from http://nchfp.uga.edu/publications/publications_usda.html