Modified Food Starches

Types of Modified Food Starches

ClearJel®, Instant ClearJel®, and ThermFlo® are modified food starches that are available in bulk food stores and some grocery stores that have a bulk food section. These and similar products are used widely in the commercial food industry and are listed on the ingredient label as modified starch. Some of the characteristics of these products make them desirable for use by the home food preserver. They are an essential ingredient in pie filling recipes found in Penn State Extension's Let's Preserve: Fruit Pie Fillings.

ClearJel

• Remains thin during processing, allowing heat to penetrate the jar completely and safely.
• Use specified amount; excess can create heat penetration problems during processing and cooling.
• Filling thickens when jars are removed from the canner and cooled.
• Only thickener recommended by the USDA for use in home canning.
• Works well with acidic ingredients.
• Tolerates high temperatures.
• Does not weep during storage.
• Not designed for freezing, breaks down when frozen and thawed.
• This type is sometimes referred to as regular ClearJel® to distinguish it from the instant type.

Instant ClearJel

• A pre-gel starch and is already cooked 
• Freezer stable
• Tolerates high temperatures
• Gradually increases in thickness during heating 
• May be frozen before or after cooking 

When baking with Instant ClearJel, increase the oven temperature and reduce the baking time to prevent "oven boil out".  Bake or freeze products with Instant ClearJel soon after preparation to avoid thinning of the product by enzymes on standing. Instant ClearJel is excellent for use in fruit pies to be frozen before or after baking. Because Instant ClearJel thickens without cooking, it is not suitable for canned pie fillings.

ThermFlo

• Provides good body
• Works well in high or low acid foods 
• Has the strongest freeze-thaw stability of these starches
• Tolerates high temperatures and long processing times 
• ThermFlo is an acceptable alternative to use in canned pie fillings
• Stable during heating and exhibits about the same viscosity during heating as regular ClearJel
• Holds up well during storage

Note: No starch, modified or regular, should be added to home-canned products unless it is called for in a scientifically tested recipe, and then it should only be used in the amount specified. 

Note: Do not use these starches to thicken soups you plan to can because this may result in under-processing of the product.

How to add modified starches to food products 

• ClearJel and ThermFlo are used as cornstarch using cold water or sugar to separate starch granules.
• Instant ClearJel is blended with sugar before being combined with liquid; then the fruit and any other ingredients are added. 
• Instant ClearJel may be cooked to increase the thickness of the product. 
• All these products show their maximum thickness upon cooling.

Modified starches can be used in place of flour or cornstarch in thickening milk sauces and gravy; however, the product will appear thinner because maximum viscosity occurs on cooling. If the sauce or gravy is to be frozen, modified starches overcome curdling and separation problems. Stirring during reheating helps to keep the product smooth.

Alternative Starches for Freezing

Although not modified food starches, arrowroot, and tapioca can be used to thicken products for freezing and yield satisfactory freeze-thaw results.

Other Modified Food Starches

In some areas of the country, modified food starches may be available by other names. Determine the properties of a particular starch before using it in home-canned products. You may be able to get this information from the manufacturer or your county extension educator.

Resources

Andress, E. and Harrison, J. (2014, updated 2020). So Easy to Preserve, 6th edition. Bulletin 989. Cooperative Extension/The University of Georgia.

Ingredion. (2023). ThermFlo technical documents.

Zepp, M., LaBorde, L., & Hirneisen, A. "Let's Preserve: Fruit Pie Fillings." (2023, August 2). Penn State Extension.