Does flour as thickener get rancid?

I'm making a tomato paste based hot sauce and thickening with corn starch but I don't like the glossy translucent appearance. I'm considering using flour instead but I've heard flour will get rancid over time because it continues to ferment in the sauce. I make batches and can it in jars. Do you know if using flour will get rancid over time?

  • Posted by: DanD
  • March 28, 2021


Lori T. March 29, 2021
They do not recommend using flour as a thickener when canning items as a rule- not because it gets rancid, but because it can make it difficult for the heat to completely penetrate the product during the canning process. The temperatures for canning would prevent anything fermenting in a properly heated and sealed jar. However, there are a few exceptions to the rule and there are professionally developed and approved canning recipes that do use a small amount of flour as a thickener. Otherwise the only approved thickener is a product called Clear Gel, which is a modified form of corn starch. Ball has a recipe for an Oriental style hot sauce that does call for a few tablespoons of flour, though- so that's something to look at and consider. Amounts you will use are important, as well as how thick the sauce will be when it goes in the jar. I expect you are thinking of a sauce that is still fluid. Perhaps you could also consider reducing the amount of liquid to start with, or cooking it down to concentrate it further before canning, as other options in lieu of either the Clear Jel or flour.
Nancy March 30, 2021
Agree with Lori - have learned the same caution about using flour as it prevents thorough heat penetration during canning.
Another suggestion is to can the tomato-paste hot sauce WITHOUT the flour and ADD some to each jar after you break the seal and start to use it. That way, presumably, you will be storing it in the fridge for a short time and the flour will not present a safety risk.
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