USDA Guide to Home Canning Apple Butter
To test for doneness, remove a spoonful and hold it away from steam for
2 minutes. It is done if the butter remains mounded on the spoon. Another way to determine when the butter is cooked adequately is to spoon a small quantity onto a plate. When a rim of liquid does not separate around the edge of the butter, it is ready for canning. Fill hot into sterile half-pint or pint jars, leaving 1/4-inch headspace. Quart jars need not be presterilized but
should be clean and kept hot until filling. Remove air bubbles
and adjust headspace if needed. Wipe rims of jars with a dampened clean paper towel. Adjust lids and process.
below 6,000 feet elevation process 10 minutes
above 6,000 feet process 15 minutes
Canning Apple Butter in Quarts
below 6,000 feet elevation process 15 minutes
above 6,000 feet process 20 minutes