How to Thicken Sauce Without Flour: Low Carb, Keto, and Gluten Free Sauce Thickeners

Dear Mark,

I’m trying to stay strictly primal/paleo, but I always run into problems when I need to thicken sauces or soups. I grew up learning to use flour/cornstarch like everyone else, but is there a good low-carb/primal alternative?

Thanks,
Raul

I received this email a while ago, but it wasn’t the first. A number of readers have expressed their confusion when it comes to thickening sauces, gravies, or soups without using traditional floury methods. The question of thickening sauces is one of the hurdles I face every time I put up a recipe post – it’s become a bit of an internal struggle (as seen with last week’s beef and broccoli stir fry recipe, in which I hesitatingly called for a teaspoon of flour as a thickener) because while adding a bit of flour or cornstarch to a larger recipe may not drastically impact the carb count, it does complicate the consistently Primal message I try to convey. This post, I hope, will resolve that struggle.

There are plenty of ways to thicken a sauce without resorting to refined starches. In fact, thickening a sauce using Primal methods can produce a richer, more satisfying meal.

Carbs in Cornstarch

There are 7g of carbs in 1 tablespoon of cornstarch. Since you only use a tablespoon or two in a whole recipe that serves four or more people, cornstarch won’t send your carb count through the roof.

A lot of people who follow paleo, Primal, or keto will want to avoid corn and its derivatives because of its naturally-occurring sugar and starch, and because it is not a nutrient-dense food.

Make a Reduction

The most rewarding way to thicken a sauce is by reduction. Indeed, learning how to reduce a sauce is important for any cook – home or professional. It’s quite simple, actually, but it’s an integral step in the thickening of any sauce or soup (whether you keep it Primal or use starches). Reduce the moisture content of a potential sauce by simmering over low heat and letting evaporation take over. The water goes, but the flavors stay. If you reduce too much, be prepared for incredibly potent flavors. Adding fats toward the end of the reduction process can complete the thickening process (more later).

Add Fat

Ah, the epic battle between fats and carbohydrates rages on. Fats can make effective thickeners, especially butter and especially with reductions. Say you’ve just seared a garlic-and-shallot-studded steak in your cast-iron pan. See those browned bits and bubbles of delicious beef fat and juices left behind? Keep the heat low and add some red wine. Scrape the good stuff off the bottom and let the wine reduce Toward the end, add a pat of cold butter and whisk it all together until smooth and creamy and viscous. Drizzle over your finished steak and veggies.

Heavy cream works well, too, especially for white sauces and soups. Again, the key is reduce, reduce, reduce.

Rendered duck, bacon, beef, or chicken fat can act like butter, if you want to avoid dairy altogether or add a different flavor profile. Just make sure you add the fat towards the end in its solid (cold) state.

Gluten Free Roux

A roux is a sauce starter or thickener that involves whisking flour into a pan containing heated fat. I’ve found that arrowroot flour is a great substitute for flour in most, if not all applications that call for a roux.

Here’s my favorite turkey gravy recipe that uses arrowroot.

Can you make a roux with almond flour?

Almonds do not have any starch, and starch is what adds structure to the cooking liquid. So, almond flour will not make a good roux.

Keto Roux

If you want a gravy-like consistency but you don’t want the carbs of arrowroot or cassava, opt for recipes that use a small amount of xanthan gum.

Pureed Veggies

Adding a few scoops of pureed vegetables is another option, especially to thicken soups. Almost any acceptably Primal veggie will work: squash, carrot, broccoli, cauliflower, zucchini, or mushrooms, just to name a few. Simply steam or soften the vegetables and then throw them in a food processor or otherwise pulverize them. Canned tomato paste works well, too. If you’re already cooking a vegetable-filled stew or soup for hours, this might happen on its own as the veggies break down and add density to the broth.

Primal Flours

You already know how much we love almond meal around here, and the other nut meals/flours can work as sauce thickeners. Unlike traditional flours, these don’t really clump when added directly to a sauce, but they can add flavors you might not expect or really want in your sauce, so be careful. You can also use nut butters – a little bit goes a long way.

I’ve heard good things about defatted coconut flour. Never used it myself, but it is an effectively low-carb (high in fiber, though). Anyone tried coconut flour?

Vegetable Gums

Vegetable gums sound a bit unappetizing, but they’re used in a lot of Asian cooking. Essentially pure fiber that absorbs moisture to form a gel, the most popular of the vegetable gums are xanthan gum and guar gum. Sprinkle over sauces while whisking to thicken, but be cautious – a little bit goes a long, long way, and too much will make your sauce “gummy” and “gooey” rather than creamy.

Vegetable gums can be a bit tricky to use properly, but there are products that make it easier. I’m interested to hear what your favorites are if you’ve used them.

Is Xanthan Gum Keto?

There are 7g of carbs per tablespoon of xanthan gum. A little bit goes a long way, and most recipes call for a tiny amount of xanthan gum – a pinch or a fraction of a teaspoon or less. Therefore, xanthan gum can be considered keto and works well as a thickener.

Some people experience gastrointestinal symptoms with gums like xanthan gum. Experiment for yourself and see how you feel.

Conclusion

I’d say reduction is the most purely Primal way to thicken a sauce, but it’s not exactly the quickest or the easiest. It remains my favorite (excepting, of course, the fact that I haven’t tried the gums) because it produces the richest flavors and textures, especially with some sort of animal fat as a thickener. The nut flours work well enough, but the resultant textures will never completely compare to those of traditional flour thickeners; nuts are just too coarse and non-absorbent. Vegetable purees are delicious, nutritious thickeners, but they have limited use (mainly in soups and stews). As for the vegetable gums, I suppose these are technically PB-friendly – they come from natural sources and they’re definitely low-carb – but I’m not sure I’d want to rely on them completely, and I’m skeptical of “low-carb”packaging. Of course, I plan on trying them at some point, and I’d love to hear your experiences with them.

Oh, and for the broccoli beef recipe? I think a vegetable gum would be your best bet. I don’t know how well butter or cream would compliment the flavors, and I doubt nut flours would blend seamlessly into the sauce; with this one, you’re just going for texture alone, and the gums would probably achieve that without compromising flavor or cooking time.

Further Reading

Guide to Fats and Oils

8 Primal-friendly Flours

Keto Bread Recipe

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