Unit 3

• Thermal Conditioning of Milk ($90^\circ\text{C}$ for 10 min):
• Heat-Induced Whey Protein-Casein Complexation:
• High-temperature preheating ($90^\circ\text{C} / 10\text{ min}$) denatures globular whey proteins, primarily $\beta$-lactoglobulin, exposing free sulfhydryl groups.
• Denatured $\beta$-lactoglobulin forms disulfide-linked covalent complexes with $\kappa$-casein on the micelle surface, preventing micellar heat coagulation and substantially increasing heat stability during subsequent sterilization.
• Conclusion: Increase in heat stability (Option 3).

Correct option: (3) Increase in heat stability

• Calculation of Retention Factor ($R_f$) in TLC:
• Mathematical Definition:

$$R_f = \frac{\text{Distance migrated by the individual compound from origin}}{\text{Distance migrated by the solvent front from origin}}$$

• dimensionless chromatographic ratio characterizing solute migration relative to mobile phase travel ($0 \le R_f \le 1$).
• Conclusion: Distance compound has moved from origin/Distance of solvent front from origin (Option 1).

Correct option: (1) Distance compound has moved from origin/Distance of solvent front from origin