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General Canning Information

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 using the correct time and pressure specified for your altitude.
  • 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 specific altitudes, fail to exhaust canners properly, process at lower pressure than specified, process for fewer minutes than specified, or cool the canner with water.

(Note: The following information applies to using the tables for selecting processing times given with food products from the USDA Complete Guide to Home Canning. Other resources may not provide the processing times and altitude adjustments in the same type of table.)

Using tables for determining proper process times

This set of guides (i.e., the USDA Complete Guide to Home Canning) includes processing times with altitude adjustments for each product. Process times for ½-pint and pint jars are the same, as are times for 1-½ pint and quart jars. For some products, you have a choice of processing at 5, 10, or 15 PSI. In these cases, choose the canner pressure you wish to use and match it with your pack style (raw or hot) and jar size to find the correct process time. The following examples show how to select the proper process for each type of canner. Process times are given in separate tables for sterilizing jars in boiling-water, dial-gauge, and weighted- gauge canners.

Example A: Boiling-water Canner

Suppose you are canning peaches as a hot-pack in quarts at 2,500 ft above sea level, using a boiling-water canner. First, select the process table for boiling-water canner. The example for peaches is given in Table for Example A below. From that table, select the process time given for (1) the style of pack (hot), (2) the jar size (quarts), and (3) the altitude where you live (2,500 ft). You should have selected a process time of 30 minutes.

Table for Example A
Recommended process time for Peaches in a boiling-water canner.
 
Process Time at Altitudes of
Style of Pack Jar Size 0 - 1,000 ft 1,001 - 3,000 ft 3,001 - 6,000 ft Above 6,000 ft
Hot
Pints
Quarts
20 min
25
25
30
30
35
35
40
Raw
Pints
Quarts
25
30
30
35
35
40
40
45

Example B: Dial-gauge Pressure Canner

Suppose you are canning peaches as a hot-pack in quarts at 2,500 ft above sea level, using a dial-gauge pressure canner. First, select the process table for dial-gauge pressure canner. The example for peaches is given in Table for Example B below. From that table, select the process pressure (PSI) given for (1) the style of pack (hot), (2) the jar size (quarts), (3) the process time (10 minutes), (4) the altitude where you live (2,500 ft). You should have selected a pressure of 7 lbs for the 10 minutes process time.

Table for Example B
Recommended process time for Peaches in a Dial-Gauge Pressure Canner.
  Canner Pressure (PSI) at Altitudes of
Style of Pack Jar Size Process Time (Min) 0 - 2,000 ft 2,001 - 4,000 ft 4,001 - 6,000 ft 6,001 - 8,000 ft
Hot and
Raw
Pints or
Quarts
10 6 lb 7 8 9

Example C: Weighted-gauge Pressure Canner

Suppose you are canning peaches as a hot-pack in quarts at 2,500 ft above sea level, using a weighted-gauge pressure canner. First, select the process time for weighted-gauge pressure canner. The example for peaches is given in Table for Example C below. From that table, select the process pressure (PSI) given for (1) the style of pack (hot), (2) the jar size (quarts), (3) the process time (10 minutes), and (4) the altitude where you live (2,500 ft). You should have selected a pressure of 10 lbs for the 10 minutes process time.

Table for Example C
Recommended process time for Peaches in a Weighted-Gauge Pressure Canner.
  Canner Pressure (PSI) at Altitudes of
Style of Pack Jar Size Process Time (Min) 0 - 1,000 ft Above 1,000 ft
Hot and
Raw
Pints or
Quarts
10 5 lb 10

Click here to print all three tables.



This document was extracted from the "Complete Guide to Home Canning," Agriculture Information Bulletin No. 539, USDA (Revised 2009).

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