Michigan State University Extension
Preserving Food Safely - 01600947
10/13/97

### Selecting the Correct Processing Time

        When canning in boiling water, more processing time

    is
    needed for most raw-packed foods and for quart jars

    than
    is needed for hot-packed foods and pint jars.

        To destroy microorganisms in acid foods processed in

    a
    boiling-water canner, you must:

        *  Process jars for the correct number of minutes in

           boiling water.

        *  Cool the jars at room temperature.

        The food may spoil if you fail to add process time

    for
    lower boiling-water temperatures at altitudes above

    1,000
    feet, process for fewer minutes than specified, or

    cool
    jars in cold water.

        To destroy microorganisms in low-acid foods processed

    with
    a pressure canner, you must:

        *  Process the jars for the correct number of minutes

        *  Allow canner to cool at room temperature until it

           is completely depressurized.

        The food may spoil if you fail to select the proper

    process
    times for altitudes above 1,000 feet, fail to

    exhaust
    canners properly, process at lower pressure than

    specified,
    process for fewer minutes than specified or

    cool
    the canner with water.

     Process times for half-pint and pint jars are the same,

    as
    are times for 1-1/2 pint and quart jars. For some

    products,
    you have a choice of processing at 5, l0, or l5

    PSIG.
    In these cases, choose the canner pressure (PSIG)

    you
    wish to use and match it with your pack style (raw or

    hot)
    and jar size to find the correct process time. An

    example
    of how to select the proper process follows.

    EXAMPLE
    OF USING TABLES FOR DETERMINING PROPER PROCESS

    TIMES

        Suppose you are canning peaches as a hot-pack in

    quarts
    at 2,500 feet above sea level. Since specific

    process
    times may vary with (l) the type of canner

    Used,(2)
    the style of pack,(3) the jar size and (4) the

    altitude
    where you live, follow these steps to find the

    recommended
    process time from one of the three following

    tables:

        1.  Locate the correct table for your type of canner.

            Look down the column labeled "Style of Pack" on

            the left side of the table and locate the correct

            line for hot-pack and quart jars.

        2.  Look across the top to find your altitude. To

            determine the correct time for you, look down the

            altitude column until you intersect the row you

            selected in Step 1.

        3.  The process pressure is 10 PSIG.

        4.  Look under process time. All jar sizes and styles

            of pack require 10 minutes.

        5.  Therefore, at 2,500 feet, process peaches for 10

            minutes at 10 PSIG in a weighted gauge pressure

            canner.

    RECOMMENDED
    PROCESS TIME FOR PEACHES IN A WEIGHTED-GAUGE

    PRESSURE
    CANNER

    Style
                   Canner Pressure (PSI) at Altitudes of

    of
           Jar       Process        0-                Above

    Pack
         Size      Time         1000 ft.        1001 ft.

    Hot
          Pints     10 min.         5 lb.           10 lb.

    Hot
          Quarts    10              5               10

    Raw
          Pints     10              5               10

    Raw
          Quarts    10              5               10

##### Go To Top of File &&&&&& MSU Extension Home Page &&&&&& Main Page for this Data Base

###### This information is for educational purposes only. References to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. This information becomes public property upon publication and may be printed verbatim with credit to MSU Extension. Reprinting cannot be used to endorse or advertise a commercial product or company. This file was generated from data base 01 on 03/09/98. Data base 01 was last revised on 10/13/97. For more information about this data base or its contents please contact wrublec@msue.msu.edu . Please read our disclaimer for important information about using our site.