Canning Apple Pie Filling: Outdated and Current Recipes
Canning apple pie filling using tapioca or cornstarch as the thickener is an outdated and risky method. Botulism is not a major risk with this product because of the high acid content of the apple filling. However, using cornstarch or tapioca may cause the filling to be too thick for the heat to penetrate to the center of the jar and kill spoilage organisms throughout the product, which is a food safety issue. Cornstarch and tapioca will also break down during the canning process and your pie filling will be runny which is a quality issue.
Clearjel® is the only thickening agent approved by the USDA for canning. Clearjel® is a modified waxy food starch which produces a smooth, heavy-bodied, gel-like product. Canned products retain this smooth texture with no liquid separation or curdling.
Another option is to can the pie filling without any starch and then thicken it with tapioca or cornstarch before putting it into the pie shell.