Curd and kadhi questionsદહીં અને કઢીના સવાલ
Setting curd runs on the weather, not on the clock, and kadhi splitting has one plain explanation behind it. Ten questions covering dahi, chhash and kadhi.
How long does curd take to set? Is winter different from summer?
It is a question of room temperature, not of the clock — curd cultures work best somewhere around 35 to 45 C. In summer, with the room at 30 to 40 C, lukewarm milk, starter and a lid are all you need: it sets in four to six hours and will turn sour if it stands for eight, so curd set overnight goes into the fridge first thing in the morning. In winter, with the room at 15 to 20 C, that same milk may not set at all on an open counter and you have to make the warmth yourself. Keep the milk a little warmer, use a thick vessel, wrap it in a cloth, stand it inside a casserole, or put it in the oven with only the light on. Reckon eight to twelve hours in winter. Lukewarm means a clean finger can stay in for five seconds; hotter than that kills the culture. Judge it by eye: set curd pulls away from the side.
How much starter should I use?
One to two teaspoons of fresh curd per cup of milk — roughly a tablespoon for half a litre. More starter does not give thicker curd; it gives faster and sourer curd, because you begin with more bacteria and more lactic acid already in the pot. Thickness comes from the solids in the milk, not from the amount of starter. What the starter is matters far more than how much: it should be one or two days old, properly set, neither sour nor watery. Whisk it smooth with a spoonful of the warm milk first and then stir that into the rest — a lump of starter dropped in whole sets only the milk around itself and leaves the rest thin. Use the upper figure in winter and the lower one in summer. The mistake is using old sour curd as starter, which gives you thin sour curd again.
My curd stays runny, or goes sour too quickly. Why?
Runny curd almost always means one of three things: the milk was not warm enough, the room was too cold, or the pot was disturbed while it was setting. Souring too fast is the opposite — the room was too warm, there was too much starter, or it stood out after it had already set. Three fixes. First, boil the milk and let it cool to lukewarm; boiling changes the milk proteins so the set comes out firmer. Second, use full-fat milk, or boil it a few minutes longer to reduce it, so there are more solids to set. Third, do not move or shake the pot during the setting hours — the gel forming inside is very fragile. And the moment it is set, into the fridge, because cold slows the bacteria down. The mistake is opening the lid every half hour and stirring it.
Why does kadhi split, and how do I stop it?
Kadhi splits because heat makes the proteins in the curd clump together. Curd holds a protein called casein spread loosely through it; heat makes those particles stick to each other into fine grains, and the acid in curd lets that happen at a lower temperature than it otherwise would — which is why you see white specks with watery whey underneath. The besan is what prevents it. Besan starch swells and gels as it heats, and that thickened liquid physically holds the protein particles apart while also raising the viscosity, so the particles cannot meet and clump. So whisk the besan completely into the cold curd and water before any heat touches it, strain if you see lumps, then bring it to a boil on a medium flame, stirring constantly in one direction — that first boil is where the starch does its work. After it, the kadhi is stable; let it simmer on low for 10 to 15 minutes. The mistake is adding besan to hot kadhi.
Does sour curd make better kadhi?
Yes, slightly sour curd gives kadhi its real character — Gujarati kadhi is meant to be khatu-mithu, and kadhi made from fresh bland curd leans entirely on the jaggery and tastes flat. But very sour curd is harder to handle: more acid means the proteins clump at a lower temperature, so the kadhi splits more readily, and with such curd whisking the besan in properly and stirring without a break matter much more. Curd two days old at room temperature, or three to four days old from the fridge, is about the sweet spot. If your curd is genuinely fresh, add a quarter to half a teaspoon of lemon juice with the heat off, or leave the curd out for a few hours. If it is screamingly sour, use more water and a little more jaggery. The mistake is using curd so far gone that it tastes bitter — that bitterness goes straight into the kadhi.
How much besan goes into kadhi?
Two tablespoons of besan to one cup of curd and three cups of water, for a pourable Gujarati kadhi for four. A tablespoon of besan is about 7 g, so two tablespoons comes to roughly 14 g. At that ratio the kadhi clings slightly to a spoon but still pours. Use less and there is not enough thickened liquid holding the protein particles apart, so it is far likelier to split. Use more and you get something closer to a gravy, and the besan tastes raw unless it has had a full fifteen minutes of simmering. Kadhi to eat with khichdi is better thin; kadhi served with bhajiya, or drunk on its own, can carry a little more besan. The mistake is eyeballing the besan and tipping it into hot liquid — it belongs whisked into the cold curd and water first.
My kadhi is too thin, or too thick. How do I fix it?
Too thin: simmer it uncovered on a low flame. Ten minutes drives off a fair amount of water and finishes cooking the besan at the same time. If it has to be thicker right now, whisk a teaspoon of besan into two tablespoons of cold water until there is no lump, stir that in, and then boil for five minutes, or the besan will taste raw. Never sprinkle dry besan into hot kadhi; it lumps instantly. Too thick: add hot water a little at a time and bring it back to a boil. Cold water poured straight into hot kadhi makes splitting more likely. And remember that kadhi thickens as it cools and thickens again when reheated, so take it off the flame a touch thinner than you actually want it. The mistake is judging the thickness while it is still at a rolling boil.
How do I make chhash from leftover curd?
One part curd to three or four parts cold water — but whisk the curd on its own until it is completely smooth first, and only then add the water. Do it the other way round, curd into water, and small lumps stay. Then salt, roasted jeeru powder, a little ginger and green chilli paste, and chopped kothmir. A cup of curd makes roughly a litre of drinking chhash. Sour curd, or curd that has separated a little, works well here, because whisking brings it back together and the water takes the edge off the sourness. Curd too sour to drink still earns its place in kadhi, in a kathol curry, or as a marinade. But if it tastes bitter, smells yeasty, or has pink or grey patches on top, throw it out. The mistake is salting before whisking smooth, since the lumps will not go after that.
How should curd be stored, and how long does it keep?
Covered, in the fridge, it stays good for four to five days — but it goes on souring the whole time, because cold slows the bacteria down without stopping them. On day one and two it is mild and properly set; by day four it is clearly khatu, which is useful for kadhi and less pleasant to eat. Keeping it covered matters, because curd picks up the smell of onion, garlic and masala remarkably fast. Use a clean dry spoon every single time: a wet or already-used spoon introduces other organisms, and the curd turns watery and off-tasting. Left out of the fridge in a Gujarat summer it will oversour and separate within three or four hours. Store it in steel or glass rather than thin plastic. Whey collecting on top is normal — just stir it back in rather than pouring it away.
My curd tastes bitter. What went wrong, and can I use it?
Bitter curd is spoiled curd, so throw it out rather than cooking with it. Sour and bitter are two different things: sourness is lactic acid and is perfectly fine, while bitterness usually means other bacteria or yeasts have started breaking down the milk's protein and fat, and it comes with a yeasty or stale smell, pink or grey patches, or a fizzy tingle on the tongue. None of that cooks out, so do not try to hide it in kadhi. Look for the cause instead: a wet or used spoon, an unwashed setting vessel, an old starter, milk that was already on the turn, or curd left sitting in the warm long after it set. Check the vessel too — curd set in aluminium or a scratched plastic box can pick up a metallic bitterness. The mistake is adding sugar to mask it.