When eggs are heated, the transparent liquid portion around yolk turns solid and turbid white. This happens due to the thermal denaturation of 

The correct answer is proteins.

Key PointsThermal Denaturation of Proteins in Eggs

• The process of cooking eggs involves heating, which causes the transparent liquid portion around the yolk to turn solid and become turbid white. This transformation is a result of the thermal denaturation of proteins, specifically the egg white proteins such as ovalbumin.
• Thermal denaturation is a process where proteins lose their tertiary and secondary structure due to the application of heat, leading to the unfolding of the protein molecules.
• As the proteins unfold, they expose their hydrophobic regions to water, which causes them to aggregate and form a solid structure. This is what causes the egg whites to turn from liquid to solid.
• The primary protein in egg white, ovalbumin, constitutes about 54% of the protein content and is the main component responsible for the coagulation and whitening effect.
• Denaturation is not limited to the application of heat. It can also occur due to mechanical action, pH changes, or the presence of certain chemicals, but in the context of cooking eggs, heat is the primary factor.

Hence, statement 2 is correct.

Additional Information

• Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. They perform a vast array of functions within organisms, including catalyzing metabolic reactions, DNA replication, responding to stimuli, and transporting molecules from one location to another.
• Eggs are considered a complete protein source, meaning they provide all nine essential amino acids necessary for the human diet. This makes them an important food source globally.
• The denaturation of proteins is not only crucial in cooking but also in biological processes and the manufacturing of pharmaceuticals, where control of protein folding and structure is essential.
• Ovalbumin, along with other proteins like ovotransferrin and ovomucoid, contributes to the unique cooking properties of eggs, making them versatile ingredients in culinary arts.