Clear-jel от John Spottiswood

This modified cornstarch is the secret ingredient that many commercial bakers use in their fruit pie fillings. Unlike ordinary cornstarch, ClearJel® works well with acidic ingredients, tolerates high temperatures, and doesn't cause pie fillings to "weep" during storage. ClearJel® is an especially good choice if you're canning homemade pie fillings, since it doesn't begin thickening until the liquid begins to cool. This allows the heat the be more evenly distributed within the jar during processing. This is such an important safety advantage that ClearJel® is the only thickener the USDA recommends for home canning. You can also use ClearJel® to thicken sauces, stews, and the like, though it's a rather expensive all-purpose thickener. One downside is that products thickened with ClearJel® tend to break down if they're frozen and thawed. If you plan to freeze what you're making, use Instant ClearJel®, arrowroot, or tapioca starch. ClearJel® is available either as pearls or powder from mail-order suppliers, but it's not yet available in grocery stores.