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Chymosin 101

Chymosin and Curd Formation

Short answer

Chymosin initiates curd formation by destabilising casein micelles, but the firmness and cutting behaviour of the resulting curd also depend on milk composition, calcium, temperature, pH and how long you let the gel develop.

By Bixa Products, Editorial teamUpdated March 10, 20265 min read

From gel to cuttable curd

A gel that has just formed is not yet a curd you should cut. It continues to firm as protein linkages develop. Cutting at the right point is a judgement about strength, not about the clock alone.

What decides how it cuts

  • Milk protein and calcium content.
  • Temperature through the set.
  • pH at the moment of addition and during the set.
  • How long you waited after the clean break.
  • How sharp your knives are and how evenly you cut.

Coagulation is never controlled by one variable. Milk composition, temperature, pH, calcium, the cheese style and your process conditions all shape how the curd forms — the coagulant is one input among several.

About the author

Bixa Products — Editorial team

Educational content written by the Bixa Products team, a family-owned cheesemaking ingredient company specializing in rennet and chymosin. Technical guidance is written conservatively: where a value depends on your milk, process or product, we say so instead of guessing for you.

  • Family-owned cheesemaking ingredient company
  • 30+ years in the Latin American cheesemaking market
  • Specialists in rennet, chymosin and milk coagulation

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