Michigan State University Extension
Preserving Food Safely - 01600501
10/13/97

### RAW AND 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 3 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.

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