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.

Two quart jars of canned apple pie filling
Two quart jars of canned apple 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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26 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.

  3. Isn’t safe to use Clear Gel when pressure canning meat such as pot pie filling for a thicker consistency? I have only read comments regarding use in pie fillings.

  4. Hi Amy, at the present time there is no tested recipe for adding Clear Gel to canned meat products. And until we have more information on that, I would recommend against it. Anytime a thickener is added to a canned food product, density is a factor. With density, we have to consider heat transfer. Heat must penetrate through out the jar to 240 degrees F in order for a low acid (meat in this case) product to be unquestionably safe. Without proper testing, there is no way to know how long it takes for heat to penetrate sufficiently when a thickener is added. Thickeners can always be added at the time of use.

  5. Hi Cat, I’m sorry but I don’t understand your question about using potatoes for apple when the recipe link is for a loaded potato soup. Further, the recipe link is not a recommended or researched based canning site. Use at your own risk.

  6. I used instant clear gel for Canning Rhubarb pie filling. Is this still safe?

  7. Hi Dorothy, Yes, Clear Gel can be used for canning rhubarb pie filling but please always do so by using a tested recipe to insure that the product is safe–proper pH, density, and processing time. Please see page 5 of Let’s Preserve Fruit Pie Fillings by Washington State University: https://s3.wp.wsu.edu/uploads/sites/2086/2014/05/Lets-Preserve-Fruit-Pie-Fillings1.pdf. If the pie filling you canned is prepared as stated in this publication, then your pie filling should be safe.

  8. Hi Maureen,
    If the recipe specifies Clear Jel, then that is what should be used. Other starches are not recommended for foods that will be home canned as they do not allow for adequate heat penetration and may clump or breakdown. If Clear Jel is not available to you, you can omit and process without. You can thicken some of the relish juice with cornstarch at the time of serving.

  9. Can I safely use less (or no) cleargel when canning my apple pie filling? The tested recipes I’ve see all have cleargel but I was hopping not to add a thickener as I don’t usually with my pies.

  10. Has any testing been done on Gaur Gum or Xanthan Gum in home canning use? I see these in commercially prepared canned goods all of the time, but have been unable to find anything on using them for home canning.

  11. Hi Tracey, no research has been done on Gaur Gum or Xanthan Gum in home canning. Clear Jel is the only thickening agent that has been thoroughly tested. And it should only be used in recipes that specify its use. In home canning, two factors are of utmost importance: pH and heat penetration. Thickening agents inhibit heat penetration. Further, beyond heat penetration, not all thickening agents are suitable as they cannot withstand the intense heat of steps in the canning process. Commercial canneries have more options that home canners due to the equipment they have to work with.

  12. Hi Sarah, pie fillings can be canned without ClearJel; if thickening is needed at the time of use, it can be added then per your favorite pie filling recipe.

  13. Hi Naomi, Clear Jel is the only recommended thickening agent for fruit pie fillings. It is not approved for use in soup. Further, no thickening agent should be used with soup unless a research-based recipe specifies. A thickening agent of choice can be added at the time of use if desired.

  14. Hi Tiff, xantham gum can be used as a thickener for jams that are made for fresh use or freezing only. Refrigerated jams should be used within 2 weeks and frozen jams should be used within 6 months.

  15. What can I use as a safe thicker for sweet and sour sauce if there are corn allergies

  16. Hi Kimberly, please supply more information. Will the sweet and sour sauce be fore fresh use or canned?

  17. I canned tart cherry pie filling that was runny. Is it possible to use Therm-Flo this year when i make cherry pie filling to thicken it up? I’m confused what Therm-Flo is a commercial form of? Pectin for freezer type jelly only? Or am I right to assume I can use it to can my filling and it will not need it be thickened more before baking like I had to do this year? Please advise

  18. Hi Gigi, thank you for reaching out to AnswerLine. Per PennState Extension, “ThermFlo® is an acceptable alternative for canned pie fillings
    since it is stable during heating and exhibits about the same viscosity during heating as regular ClearJel®. It has the added
    advantage of holding up well during storage.” ThermFlo, like ClearJel, is a modified corn starch, not a pectin. Use this link to learn more: https://extension.psu.edu/downloadable/download/sample/sample_id/57582/

  19. Hi I have the all new ball book of canning and preserving, my question is: a recipe for strawberry rhubarb pie filling & a recipe for peach raspberry pie filling in the book calls for 1/2 cup of cornstarch, and yes this is a canning recipe since it states filling your jars and processing them, so my question for this is, if this is a tested recipe why is cornstarch allowed for this specific recipes while canning.?. The book is a First Edition 2016. Are these 2 recipes safe.?. & if they are then why is it safe in these recipes but not in others.?.

  20. Oh I’m sorry I just realized they are in the freezer section…. Sorry about that… smh

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