Question

Which of the following sequence of events occurs during formation of egg-white gel?
Assume: P\(_N\): Native protein; P\(_D\): Denatured protein; P\(_A\): Aggregated protein; P\(_G\): Protein gel.
Notation:
- \(\Delta\): heating,
- \(\nabla\): cooling,
- \(\rightarrow\): forward reaction,
- \(\leftrightarrow\): reversible reaction.

• A. \(P_N \; \overset{\Delta}{\leftrightarrow} \; P_D \; \overset{\nabla}{\leftrightarrow} \; P_A \; \overset{\nabla}{\leftrightarrow} \; P_G\)
• B. \(P_N \; \overset{\Delta}{\leftrightarrow} \; P_D \; \overset{\Delta}{\rightarrow} \; P_A \; \rightarrow \; P_G\)
• C. \(P_N \; \overset{\Delta}{\leftrightarrow} \; P_D \; \overset{\nabla}{\rightarrow} \; P_G\)
• D. \(P_N \; \overset{\Delta}{\rightarrow} \; P_A \; \overset{\Delta}{\rightarrow} \; P_G\)

Hint:

Protein gelation sequence: Native protein \(\xrightarrow{\Delta}\) Denaturation \(\xrightarrow{\Delta}\) Aggregation \(\rightarrow\) Gel formation.

Answer 1

The Correct Option is B

Step 1: Denaturation of proteins.
- Egg-white proteins (ovalbumin, conalbumin, etc.) are native (\(P_N\)) in raw egg. - Upon heating (\(\Delta\)), they unfold → denatured state (\(P_D\)).

Step 2: Aggregation.
- Denatured proteins lose solubility and expose hydrophobic groups. - Further heating causes aggregation (\(P_A\)).

Step 3: Gelation.
- Aggregated proteins crosslink via hydrophobic, hydrogen, and disulfide bonds. - Leads to formation of a continuous 3D structure: the protein gel (\(P_G\)).

Step 4: Analyze options.
- (A) Shows reversible cooling steps → incorrect (denaturation is largely irreversible). - (B) Correct: \(P_N \;\xrightarrow{\Delta}\; P_D \;\xrightarrow{\Delta}\; P_A \;\rightarrow\; P_G\). - (C) Skips aggregation step → incomplete. - (D) Jumps from native to aggregate without denaturation step → incorrect. Final Answer: \[ \boxed{\text{(B)}} \]