Ensuring High-Quality Canned Foods (2/2)

Title:
Ensuring High-Quality Canned Foods (2/2)

Yield:
1 Guide

Categories:
Canning,
Information




Ingredients:









 Advantages of Hot-packing


 


 Many fresh foods contain from 10 percent to more than 30 percent air. How


 long canned food retains high quality depends on how much air is removed


 from food before jars are sealed.


 


 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.


 


 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. Controlling Headspace


 


 The unfilled space above the food in a jar and below its lid is termed


 headspace. Directions for canning specify leaving 1/4-inch for jams and


 jellies, 1/2-inch for fruits and tomatoes to be processed in boiling water


 and from 1- to 1-1/4-inches in low- acid foods to be processed in a


 pressure canner This space is needed for expansion of food as jars are


 processed, and for forming vacuums in cooled jars. The extent of expansion


 is determined by the air content in the food and by the processing


 temperature. Air expands greatly when heated to high temperatures; the


 higher the temperature, the greater the expansion. Foods expand less than


 air when heated.


 


 ======================================================= === * USDA


 Agriculture Information Bulletin No. 539 (rev. 1994) * Meal-Master format


 courtesy of Karen Mintzias


 


 From Gemini's MASSIVE MealMaster collection at www.synapse.com/~gemini