β-Lactoglobulin

The dominant whey protein of cow’s milk, absent from human milk, a lipocalin that binds small hydrophobic molecules such as retinol and fatty acids. It is the major allergen of cow’s milk, responsible for most milk-protein allergy, which is why its presence drives allergen labelling of dairy ingredients. Its heat denaturation above about 70 °C causes it to aggregate with casein micelles, affecting the texture of heated milk, yoghurt firmness, and fouling of heat exchangers, making its behaviour a central concern of dairy processing. Whey protein ingredients are largely β-lactoglobulin, valued for gelling, foaming, and emulsifying. Its absence from human milk complicates infant-formula design.