Thickeners for Home Canning

Home canned fruit pie fillings make it easy to prepare delicious pies and desserts all year long. Since 2015 the USDA and the National Center for Home Food Preservation has recommended Clearjel® (cook type, not instant) as the thickening agent for some home canned fruit pie fillings.  There is not a safe substitute for Clearjel® when canning pie filling.

Clearjel® is a flavorless, modified cornstarch that doesn’t break down through the canning and baking process.  It can withstand a variety of pH levels and allows for adequate heat penetration during processing to render a shelf-safe product.  Clearjel® differs from other thickeners such as regular cornstarch, flour, and tapioca which thicken with heat, become dense, clump, break down with additional cooking, and do not allow for adequate heat penetration during processing. Without heat penetrating throughout the jar, yeast, mold, or other harmful bacteria can form. Clearjel® only thickens a small amount with heat; thereby, reducing the density and heat penetration issues during processing. Heat is able to penetrate the contents of the jar completely and safely.  The filling thickens in the jar after the jars are removed from the canner and the food cools. Clearjel® does not break down over multiple heatings as other thickeners might. In home-canned pie fillings, it easily survives the three heatings of preparation, processing, and eventual baking. 

To use, follow directions in Fruit Pie Fillings for Home Canning by Washington State University.  Care should be taken to not exceed the specified amount of thickener to avoid jelling, oozing*, or inadequate heat penetration. 

The shelf-life of Clearjel® in canned foods is excellent. Canned products retain a smooth texture with no liquid separation, weeping, or curdling during storage.  Like most home canned foods, pie fillings should be used within a year for best quality.

Clearjel® is not designed for freezing as it breaks down through freezing and thawing. Instant Clearjel® is freezer stable yet tolerates baking temperatures.  It thickens without cooking and begins to swell as soon as it is added to liquid gradually increasing in thickness during heating.  Although not modified food starches, arrowroot and tapioca starch can also be used to thicken products for freezing yielding satisfactory freeze-thaw results. Do not use Instant Clearjel® in canned pie fillings.

While Clearjel® is widely used commercially, its manufacturer, Ingredion, has not made it easily available to consumers. Therefore, it behooves one to think ahead. It is generally sold in bulk and is available only through a few supply outlets; it is not currently available in traditional grocery stores.  Look for it at online sources, Amish groceries, or bakery supply stores.  If Clearjel® is not available at the time of preserving, pie filling can be made without and thickened at the time of use with any suitable starch.  There are about 3 cups of Clearjel® in a pound.

At the present time, the USDA, the National Center for Home Food Preservation, and most University Extensions, including Iowa State University Extension and Outreach and Minnesota Extension, stand by Clearjel® as the only recommended starch for four pie fillings– apple, blueberry, cherry, and peach pie fillings; there have been no broadening of recommendations from the USDA or NCHFP for other uses. However, some University Extensions have expanded the use of Clearjel® with tested canning applications or alternative products.  Food scientists at Oregon State University Extension have added a Blackberry Pie Filling option to the list of approved USDA pie filling recipes by following the USDA cherry recipe with blackberry as a substitute. Washington State University Extension has added recipes for making jams with Clearjel®.

PermaFlo®, ThermFlo® and Thick Gel™ are commercial equivalents that have been accepted as alternatives for Clearjel® by some University Extensions.  Penn State prefers ThermFlo® as an alternative for its “added advantage of holding up well during storage if canned goods are stored in a cold basement.  This stability factor allows it to be used in frozen pie fillings.” ThermFlo® is also made by Ingredion. Utah State Extension recognizes Thick Gel™ as an alternative for Clearjel®. Thick Gel™ is made and marketed by Cornaby’s, a Utah based company, which sells directly to consumers.  It advertises itself as gluten-free and non-GMO.  (Per the Ingredion website, Clearjel® is also gluten-free.)  PermaFlo® was not found to be mentioned by any particular University Extension; it is a product of Tate & Lyle International.

As always, to ensure a safe product, use a tested canning recipe without alteration and follow the latest guidelines; the National Center for Home Food Preservation, USDA Complete Guide to Home Canning, and So Easy to Preserve are trusted sources. If other recipes or products are used, check with the manufacturer or recipe source regarding use and product safety.

Marlene Geiger

I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.

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2 thoughts on “Thickeners for Home Canning

  1. I am interested in canning a strawberry green tomato jam. It requires Jello. I have read that it is not safe to waterbath can Jello jams, but can I safely pressure can it? If so, how?

  2. Hi Cheryl, I am not sure where you got your information about using a pressure canner to preserve this jam, but it is erroneous. Any jam made with jello must be preserved by freezing for both quality and safety. Jello will breakdown if heated by hot water bath or pressure canner. We always encourage one to use tested recipes to make sure that the product is safe and also is of a desirable quality after the effort to prepare it. Jello jams do freeze well or can be refrigerated for up to 3 weeks.

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