______________ is a globular protein found in milk.

Casein is indeed a globular protein found in milk, making it essential for various dairy products and an important source of nutrition. Casein accounts for about 80% of the proteins in cow's milk and is unique in its ability to form a gel or curd when exposed to acid or rennet, which is fundamental in cheese-making processes.

Its structure allows for the slow release of amino acids, making it beneficial for muscle repair and growth. The globular structure of casein contributes to its solubility in the milk environment, where it exists as micelles, effectively making it accessible for digestion and absorption.

In contrast, keratin and elastin are structural proteins primarily found in hair, skin, and connective tissues, respectively, and gluten is a protein complex found in wheat and related cereals, not in milk. This emphasizes the specificity of casein as a milk protein, fundamental in both nutrition and food science applications.