To can apples to use in pies, core, peel and slice the apples to the preferred thickness. Next, make a thickener or syrup and then fill quart-sized jars with the sliced apples and syrup, leaving about 1/2 inch of head space. Seal the jars and place in a water bath.
To make 7 quarts of canned apple pie filling, peel, core and slice 6 pounds of apples. Pack the sliced apples into sterilized quart jars, leaving extra space at the top. Next, in a large pan, combine 4 1/2 cups of white sugar, 1 cup of cornstarch, 2 teaspoons of ground cinnamon and 1/4 teaspoon of nutmeg. Once the ingredients have fully combined, add 2 teaspoons of salt and 10 cups of water and bring to a boil. Cook until the mixture is thick and bubbly.
Remove the syrup from heat and add 3 tablespoons of lemon juice and 2 drops of yellow food coloring. Fill each jar with the syrup, still leaving the head space, and use a knife to get rid of any bubbles. Clean the rim of each jar and put the lids and rings onto the jars. Carefully place each jar into a water bath canner for 20 minutes.
To use a water bath canner, fill the pot with enough water to submerge each jar and have about 2 inches extra above each jar. After placing the jars in the water bath canner, cover and bring the water to a boil. Once the water is boiling, start the timer.