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How does mayonnaise become firm during preparation?

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Plate of sushi rolls with salmon, vegetables, and rice wrapped in seaweed, served with chopsticks and a small bowl of soy sauce on a wooden table. — gastronomy A common rice dish of Japanese cooking is sushi. To make a type known as *maki-zushi*, a sheet of seaweed is spread with rice flavored with vinegar. Seafood or vegetables and garnishes are then placed on top. Finally, the whole sheet is rolled into a cylinder and sliced.

Mayonnaise becomes firm during preparation through the process of creating an emulsion, which involves the continuous beating of egg yolks while adding vegetable oil gradually.1

The firmness is achieved because the egg yolk acts as an emulsifier, containing substances like lecithins that stabilize the mixture. The emulsifier has a hydrophobic portion that dissolves in the oil and a hydrophilic portion that dissolves in the aqueous phase (such as vinegar or lemon juice), allowing the oil to be suspended as small droplets within the liquid. As more oil is incorporated into this stable suspension through constant agitation, the mixture thickens into a firm, creamy consistency.21