Hung Curd (Gravity-Straining Yogurt)

What It Is

Hung curd, chakka in the Indian kitchen, is yogurt from which the whey has been allowed to drain under gravity. The yogurt goes into cloth over a sieve, the fridge does the rest, and what stays behind is a dense, tangy concentrate of casein, milk fat and the remaining water.

Roughly half the weight leaves as whey. A kilo of full-fat yogurt gives somewhere between 450 and 550 g of curd after 8 to 12 hours, depending on the yogurt's starting solids, how cold the fridge runs and how long it hangs.

The distinction that matters is gravity versus force. Commercial Greek yogurt is strained by centrifuge, and many thick supermarket yogurts are not strained at all but thickened with milk powder, cream or starch. Both arrive at a similar apparent thickness by a different route, and both behave differently once you start whisking sugar into them.

Why It Matters

Acid. Water leaves, lactic acid largely stays, so hung curd is noticeably sharper than the yogurt it came from. In shrikhand that concentrated sourness is the entire point: it is what lets a sweetened dessert close a rich meal by resetting the palate instead of adding another layer of fat.

Texture. Gravity-hung curd whisks to a smooth, glossy, almost mousse-like body within a minute. Centrifuged Greek yogurt at the same thickness tends to go grainy and chalky when sugar is beaten through it, because its protein network has been disrupted mechanically rather than simply relieved of water.

The whey. It is acidic, lightly protein-rich and faintly sweet. In a bread dough its acidity firms the gluten; it can replace part of the milk in a naan dough made the same weekend, or go into a lassi.

How to Execute

Choose the yogurt. Full-fat, plain, with live cultures and nothing else. Read the label: milk powder, starch or gelatine mean it will drain poorly and taste flat. Lactose-free yogurt drains identically, because the casein is unchanged.

Set up. Line a sieve with doubled muslin or a thin, clean tea towel. Stand it over a bowl deep enough that the base of the sieve stays well clear of the collected whey, or it ends up sitting in it.

Hang it cold. Yogurt in, cloth folded loosely over the top, into the fridge. Do not press, twist or weight it.

Time sets the texture. About 4 hours gives a thick, pourable yogurt. 8 to 12 hours gives the standard shrikhand or labneh body. Around 24 hours gives something firm enough to roll into balls. Overnight runs of 14 to 15 hours are fine, but expect a firmer curd.

Weigh what you get. Tip the curd into a bowl and put it on the scale. This is the step most recipes skip and the one that decides whether the dish is right.

Season by percentage. Set sugar against the actual curd weight. Around 20% gives a clearly tart shrikhand that cuts a rich meal; classic sweet versions go far higher. Add three quarters, taste, then the rest, because sugar can be added and never removed. Use icing sugar: granulated will not dissolve into cold curd and leaves it sandy.

Lactose-free yogurt reads sweeter. Lactase has already split the lactose into glucose and galactose, both sweeter than lactose, so the plain curd tastes sweeter before anything is added. Start nearer 15% and taste up.

Common Mistakes

Substituting shop-bought Greek yogurt. It looks like the same thing and saves a night. It is not, and it goes chalky with sugar.

Squeezing the cloth to hurry it. Pushes fat and fine protein through into the whey and leaves a drier, less rich curd.

Hanging at room temperature. It drains faster and also keeps fermenting, souring in an unpleasant way, and over a night that is a food-safety question too.

A fixed sugar weight. The commonest reason a shrikhand comes out cloying or flat. One overnight batch of 850 g yogurt was expected to give 390 g and gave 440 g; the planned 75 g of sugar would have been 17% and tasted dull, and the planned milk to loosen an over-drained curd was not needed at all. Weigh, then decide.

Loosening by reflex. Add milk only if the curd has drained hard and is genuinely stiff, and then a tablespoon at a time. Any flavoured liquid you are adding anyway, such as saffron milk, often does the job alone.

Throwing the whey away. Free, acidic, useful liquid.

How to Tell When You've Nailed It

On the spoon. At 8 to 12 hours the curd holds a clean shape and does not slump back. A spoon drawn through it leaves a trench that stays.

In the bowl. Uniformly smooth, no visible separation. A grainy look at this stage almost always means the starting yogurt had thickeners in it.

On the tongue. Plain, it should taste sharply and cleanly sour with a full dairy body. Bitterness or a fizz means it was too warm or went too long.

Under the whisk. With icing sugar it turns glossy within thirty seconds and holds soft ribbons. If it stays matte and grainy, no further whisking will fix it; the problem was the yogurt.

Make-Ahead

This is an overnight job by nature. Set the yogurt hanging the evening before, finish the shrikhand in the morning, and it is better again after a few hours in the fridge as any aromatics infuse. Finished shrikhand keeps three days chilled; the whey keeps about the same.