casein

American  

[key-seen, -see-in, key-seen] / ˈkeɪ sin, -si ɪn, keɪˈsin /

noun

1. Biochemistry. a protein precipitated from milk, as by rennet, and forming the basis of cheese and certain plastics.

2. Fine Arts.

   1. an emulsion made from a solution of this precipitated protein, water, and ammonia carbonate.

   2. a paint in which this emulsion is used as a binder.

   3. a picture produced with this paint and emulsion.

---

casein British  

/ -siːn, ˈkeɪsɪɪn /

noun

1. Also called (US): paracasein.  a phosphoprotein, precipitated from milk by the action of rennin, forming the basis of cheese: used in the manufacture of plastics and adhesives

---

casein Scientific  

/ kā′sēn′,-sē-ĭn /

1. A white, tasteless, odorless mixture of related phosphoproteins precipitated from milk by rennin. Casein is very nutritious, as it contains all of the essential amino acids as well as all of the common nonessential ones. It is the basis of cheese and is used to make plastics, adhesives, paints, and foods.

---

Etymology

Origin of casein

1835–45; < Latin cāse ( us ) cheese ¹ + -in ²

Example Sentences

The study found that diets rich in casein, the primary protein found in milk and cheese, along with wheat gluten, greatly reduced how much cholera bacteria could colonize the gut.

From Science Daily • Apr. 7, 2026

Other companies also use bacteria or fungi to produce casein.

From BBC • Jul. 12, 2025

The fatty acid composition, phospholipid composition, and protein composition, including casein and whey protein genetic variations, were, in general, remarkably similar.

From Science Daily • Mar. 27, 2024

As the digestive system breaks down the casein, it forms peptides called casomorphins.

From Salon • Oct. 9, 2023

Origin.—Lactic acid is obtained from sour milk, resulting from the fermentation of the sugar of milk under the influence of casein.

From New, Old, and Forgotten Remedies: Papers by Many Writers by Anshutz, Edward Pollock