Fine-mesh strainer of thick yogurt over a glass bowl

Straining Took Too Long: Causes and Fixes

ByCraig Brockie Last updated

Why your yogurt is straining so slowly

You spooned yogurt into a strainer expecting thick, Greek-style yogurt in a few hours. Hours later it still looks loose, and the bowl underneath holds only a little whey. Slow straining is common, and on its own it is not a sign that anything has gone bad.

It helps to know what normal looks like. University of Illinois Extension drains Greek-style yogurt for 2 to 4 hours and yogurt cheese for 8 to 24 hours, covered, in the refrigerator. Washington State University Extension also gives 8 to 24 hours in the fridge for yogurt cheese. If you are well past those windows with little change, one of the causes below is the likely reason.

The most likely cause: a firm yogurt that holds its water

How a yogurt gel is built decides how easily whey can escape. In a 2004 lab study by Lee and Lucey at the University of Wisconsin, gels made at a lower incubation temperature (40°C, or 104°F, versus about 46°C, or 115°F) and with more starter were firmer, less permeable and lost less whey. A less permeable gel is great in a cup and slow in a strainer.

How you treat the milk matters too. A 2023 review of yogurt syneresis (the scientific word for whey separation) reports that stronger heat treatment of the milk, such as 85°C (185°F) for 30 minutes, added milk proteins such as milk powder, and cultures that make exopolysaccharides (natural thickeners made by some bacteria) all help yogurt hold on to water.

So if you heated your milk long and hot, stirred in milk powder, or used a thick, stretchy culture, slow straining is the trade-off for a sturdier yogurt, not a mistake.

How to speed up straining safely

Wide strainer lined with cheesecloth holding a shallow layer of yogurt
  1. Keep it cold. Strain covered in the refrigerator at 40°F or below, as Illinois Extension advises. Straining on the counter is faster, but USDA guidance says perishable food should not sit at room temperature for more than 2 hours, or 1 hour above 90°F.
  2. Break the set first. Before it goes into the strainer, stir the chilled yogurt gently a few times with a clean spoon. Large unbroken pieces of set yogurt release whey slowly.
  3. Spread it out. Use a wider strainer so the layer is about 2 to 3 inches deep instead of a tall mound. The whey has a shorter path out of a shallow layer.
  4. Check the filter. Paper coffee filters and tightly woven cloth drain slowly. A fine-mesh strainer, or a strainer lined with one layer of cheesecloth, lets whey through faster while holding back the curd.
  5. Scrape once. After about 2 hours, use a spatula to lift the thick layer pressed against the mesh and fold it toward the middle. Do not squeeze or press, which pushes curd through with the whey.
  6. Give it the full time. Check Greek-style yogurt at 4 hours and yogurt cheese at 8 hours, then keep going in the fridge up to 24 hours if you want it thicker.

Other causes to check

The batch never fully set

A soft, partly set batch can clog the filter with fine curd, and the liquid that drips out may look milky instead of clear yellow-green. If the yogurt smells like plain milk rather than tangy, it may not have cultured at all. See yogurt did not set and how to verify your yogurt actually cultured before you keep straining.

Too much yogurt in one strainer

Doubling a batch in the same strainer roughly doubles the depth, and the bottom layer packs down under the weight above it. Split large batches between two strainers or strain in rounds.

Plant-based yogurt

Many plant yogurts rely on added starches or gums for body and do not release whey the way dairy yogurt does, so straining may do little. Plant milk that would not thicken covers better options.

How to prevent slow straining next time

  • Skip extras you do not need. If you plan to strain anyway, standard heating to 180°F to 185°F (Illinois Extension) is enough. Extra milk powder and long, hot holds make a yogurt that clings to its whey.
  • Use a recipe made for straining. Our guides to making Greek yogurt and Greek yogurt with a yogurt maker walk through the whole process.
  • Chill before straining. Cold, fully set yogurt holds together on the mesh and drains clear whey.
  • Plan the time. Start yogurt cheese in the evening and let it drain overnight in the fridge.
  • Save the whey. The liquid you drain is useful. See recipes using whey from yogurt.

When to throw the batch out

Slow straining alone does not make yogurt unsafe. These signs do:

Related topics

Sources

Craig Brockie is the founder of Ultimate Health Solutions, the company behind Ultimate Gut, and the author of Ultimate Health, The Ultimate Gut Health Guide and The Unlimited Probiotics Guide. After injuries and chronic health problems in his twenties that conventional care didn’t resolve, he began researching health on his own and has studied natural health for 30 years. He is not a medical professional, and his articles are general information, not medical advice.

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