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The Science Behind Food Preservation Methods: Hot vs. Raw Pack Peaches
by Original Author: Megan Wells, Pulaski County | Adapted for Blog: Torrie Smith, Van Buren County
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. 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.
CAUTION: Do not use this process to can white-flesh peaches. There is evidence that some varieties of white-flesh peaches are higher in pH (i.e., lower in acid) than traditional yellow varieties. The natural pH of some white peaches can exceed 4.6, making them a low-acid food for canning purposes. At this time there is no low-acid pressure process available for white-flesh peaches nor a researched acidification procedure for safe boiling water canning.Freezingis the recommended method of preserving white-flesh peaches.
Quantity:An average of 17½ pounds is needed per canner load of 7 quarts; an average of 11 pounds is needed per canner load of 9 pints. A bushel weighs 48 pounds and yields 16 to 24 quarts – an average of 2½ pounds per quart.
Quality:Choose ripe, mature yellow-flesh peaches of ideal quality for eating fresh or cooking.
Procedure:Dip fruit in boiling water for 30 to 60 seconds until skins loosen. Dip quickly in cold water and slip off skins. Cut in half, remove pits and slice if desired. To prevent darkening, keep peeled fruit inascorbic acid solution. Prepare and boil a very light, light, or mediumsyrupor pack peaches in water, apple juice, or white grape juice. Raw packs make poor quality peaches.
Hot pack– In a large saucepan place drained fruit in syrup, water, or juice and bring to boil. Fill jars with hot fruit and cooking liquid, leaving ½-inch headspace. Place halves in layers, cut side down.
Raw pack– Fill jars with raw fruit, cut side down, and add hot water, juice, or syrup, leaving ½-inch headspace.
Adjust lids and process.
Processing directions for canning peaches in a boiling-water canner are given inTable 1.
Table 1. Recommended process time for Peaches, halved or sliced in a boiling-water canner.
|Style of Pack and Jar Size||Process Time at 0 - 1000 ft||Process Time at 1,001 - 3,000 ft||Process Time at 3,001 - 6,000 ft||Process Time above 6,000 ft|
|Hot, Pints||20 min||25 min||30 min||35 min|
|Hot, Quarts||25 min||30 min||35 min||40 min|
|Raw, Pints||25 min||30 min||35 min||40 min|
|Raw, Quarts||30 min||35 min||40 min||45 min|
Table 2. Process Times for Peaches (Halved or Sliced) in a Dial-Gauge Pressure Canner.
|Style of Pack||Jar Size||Process Time (Min)||PSI at Altitudes of 0 - 2,000 ft||PSI at Altitudes of 2,001 - 4,000 ft||PSI at Altitudes of 4,001 - 6,000 ft||PSI at Altitudes of 6,001 - 8,000 ft|
Table 3. Process Times for Peaches (Halved or Sliced) in a Weighted-Gauge Pressure Canner
|Style of Pack||Jar Size||Process Time (Min)||PSI at Altitudes of 0 - 1,000 ft||PSI at Altitudes Above 1,000 ft|
For more information, check out the website for the National Center for Home Food Preservation or contact your Family and Consumer Sciences at your County Extension Office.