Which of the following are protein thickeners?

• A. Gelatin, Egg Yolk, Casein
• B. Acacia, Pectin
• C. Sorbitan Esters
• D. Colloidal Clays

Answer: (A)

Protein-based thickeners rely on protein networks forming to trap water and raise viscosity. Gelatin, egg yolk, and casein fit this because they are proteins that can develop gel-like or viscous networks when heated and/or mixed with other ingredients. Gelatin, from collagen, dissolves in hot water and then forms a gel as it cools, thickening liquids. Egg yolk contains several proteins that, along with emulsifiers, help create a thicker, smoother texture in sauces and custards when heated or emulsified. Casein, the main milk protein, forms gels and thickens dairy products when acidified or heated, increasing viscosity. The other options are not proteins: acacia and pectin are polysaccharide plant thickeners; sorbitan esters are emulsifiers; colloidal clays thick en by particle swelling, but they’re inorganic, not protein-based.