Home Canning - Selecting The Correct Processing Time

Intro - How Canning Preserves - Ensuring Safe Canned Foods - Ensuring High Quality - Special Diets - Preparing Butters - Pickled and Fermented Foods - Recommended Canners - Correct Processing Time - Jars and Lids - Testing Jar Seals

United States Department Of Agriculture, Extension Service

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.

Using Tables for Determining Proper Process Times

The set of guides includes processing times with altitude adjustments for each product. Process times for 1/2-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, 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

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 the type of canner to be used (boiling-water canner). The example for peaches is given below. From Table 1, 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.

Example B

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 the type of canner to be used (dial-gauge canner). The example for peaches is given below. From Table 2, 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.

Example C

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 the type of canner to be used (weighted-gauge pressure canner). The example for peaches is given below. From Table 3, 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.

Tables

Table 1.

Table 1. 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	20 min	25 min	30 min	35 min
Hot	Quarts	25	30	35	40
Raw	Pints	25	30	35	40
Raw	Quarts	30	35	40	45

Table 2.

Table 2. Recommended process time for Peaches in a dial-gauge pressure canner.
			Canner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time	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 min	6 lb	7 lb	8 lb	9 lb

Table 3.

Table 3. Recommended process time for Peaches in a weighted-gauge pressure canner.
			Canner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time	0 - 1,000 ft	Above 1,000 ft
Hot and Raw	Pints or Quarts	10 min	5 lb	10 lb

Extracted from the "Complete Guide to Home Canning." First published: January, 1993. Reviewed: June, 1998.
Courtesy of the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS)