What causes yogurt in sauces to split? How to prevent it?
A lot of my favorite curry recipes have a yogurt based sauce in them, but on a pretty regular basis when I make them, the yogurt ends up splitting into basically curds and whey. What causes that, and how can I prevent it?
As an illustrative example, last night I made a simple tofu curry as follows:
- warm evoo in a pan
- add chopped onion, saute briefly
- add curry seasonings, allow to warm/season the oil
- add cubed tofu, toss to coat
- cook for a while, tossing periodically to lightly brown the cubes
- turn heat off
- add plain greek yogurt
- stir to combine
In the few minutes it took to finish the rest of the meal and start plating, the yogurt had separated so I had a clumpy, lumpy, yogurt soup instead of a smooth creamy sauce.
Best Answer
Yogurt is a mesh of denatured milk protein that traps the whey.
When yogurt is over-heated those proteins tighten and squeeze out the extra whey. When the protein matrix is cut it will also leak whey.
To combat this add a little starch. A little cornstarch mixed into the yogurt will prevent the yogurt proteins from over-coagulating. All heated yogurt sauces that I have seen include starch for this reason.
I should also add that this problem occurs mostly with lowfat yogurt. Extra milk fat in yogurt will interfere with the protein's ability to coagulate the same way the starch does.
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How do you keep yogurt from splitting in a sauce?
Here are three techniques to stabilize yogurt in sauce.How do you stabilize yogurt for cooking?
For hot soups, you'll need to temper the yogurt to avoid curdling. Add a small amount of warm-but-not-boiling soup to a bowl, whisk in the yogurt, then add the mixture back into the soup.How do you add yogurt to soup without curdling?
Yogurt curdles in heat when the protein strands tighten up or congeal. A non-fat or low-fat yogurt will curdle much easier in heat, as there is not much fat protecting the protein strands from tightening up from direct contact to the heat.How to stop yoghurt from splitting
More answers regarding what causes yogurt in sauces to split? How to prevent it?
Answer 2
You are trying to add the yoghurt at too high a temperature. Let the dish cool to around 75 deg C before adding the yoghurt, and make adding the yoghurt the last thing you do before serving.
Answer 3
In addition to reducing the temperature of the curry, you can also:
- Temper the yoghurt - combine a small amount of the warm sauce to the yoghurt before adding it to the curry. This helps when adding cream, milk, or eggs to a sauce.
- Whisk the yoghurt - use a fork or whisk and vigorously mix the yoghurt. As the fats and proteins are emulsified in the liquid, this ensures an even starting distribution.
- Add an emulsifier - add a teaspoon of mustard powder or lethicin to the curry before combining the yoghurt.
Answer 4
One option is to substitute cream for yoghurt.
That's what's done in a lot of Indian cooking. When yoghurt is used, it's usually added at the end, and not at high heat, just as James points out.
Answer 5
Stir a little starch into the yogurt before adding it to the hot dish & it will not split.
The usual ratio is-
2 tsp white flour to 1 cup yogurt
1 tsp corn starch to 1 cup yogurt
1 tsp gram flour to 1 cup yogurt
1 tsp rice flour to 1 cup yogurt
Also, remove the dish from the heat source & stir yogurt mixture in, then return dish to heat source to warm dish through and you won't get lumps.
This also works with other dairy products to prevent splitting like heavy cream & buttermilk.
Answer 6
I've also seen another suggestion: strain out the vegetables/meat from the sauce, add yoghurt to the sauce one tablespoon at a time, whisk it in very quickly, and bring the dish back up to a boil, stirring the whole time, before adding a second tablespoon.
I've found that approach to work quite well.
I think the reason this works is that the yoghurt is quickly dissolved in the sauce to the point that there are no macroscopic clumps, and then each microscopic clump of yogurt is deliberately curdled by bringing the sauce to a boil, which prevents macroscopic curdles from forming later, and results in a smooth texture despite thoroughly cooking the yoghurt.
Answer 7
I concur with adding starch to prevent separation of a yogurt-based sauce with the caveat that one should NOT use arrowroot or lecithin. Arrowroot is a great thickener, but when used with dairy, arrowroot turns the mixture to a very unappealing slimy, mucous glop. The same holds true for using lecithin powder, another fine emulsifier to have in your "kit." Again, with dairy products, lecithin tends to turn the sauce slimy. There are many alternatives to arrowroot and lecithin which do work well, including powdered tapioca starch, potato starch (really good), rice flour and corn starch as already mentioned. I find it best to mix the starch with a bit of cold water first to form a slurry or paste and then add this to the yogurt sauce, little by little, and one can get the desired thickness and prevent separation, and avoid lumps entirely.
Answer 8
Put the yoghurt in a bowl and carefully stir the sauce, not too hot, into the yoghurt! i.e. Do it the other way round.
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