Quality Control

• Scientific Basis of Pasteurization Standards:
• Complete Destruction of Pathogens: Thermal regimes ($63^\circ\text{C}$ for $30\text{ min}$ LTLT, or $72^\circ\text{C}$ for $15\text{ sec}$ HTST) are designed to destroy the most heat-resistant non-spore-forming vegetative pathogen (Coxiella burnetii and Mycobacterium tuberculosis) (True).
• Inactivation of Alkaline Phosphatase: Alkaline phosphatase is an endogenous milk enzyme whose thermal inactivation curve slightly exceeds that of M. tuberculosis. Absence of residual alkaline phosphatase serves as the statutory test for pasteurization efficiency (True).
• Preservation of Cream Line: Thermal exposure must not excessively denature cryoglobulins, preserving natural gravity creaming (True).
• Fat Globule Size Reduction (B): Achieved by homogenization, not pasteurization.
• nalysis:
• ((A), (C) and (D) only): Correct.

Correct option: (3) (A), (C) and (D) only

• Properties of Homogenized Milk:
• Brighter and Whiter Appearance: Homogenization shears fat globules, increasing their number by orders of magnitude and expanding total surface area, which dramatically increases light scattering. (True)
• Produces Soft Curd: Reduced fat globule size and adsorption of caseins onto fat surfaces weaken the casein micelle network during coagulation, significantly lowering curd tension (yielding easily digestible soft curd). (True)
• Separation of Fat is Prevented: Stokes' law dictates creaming velocity:

Because droplet radius $r$ is drastically reduced, creaming velocity becomes negligible, preventing cream layer formation. (True)

• Diameter Specification (B): Commercial homogenization reduces fat globule diameter to $\lt 2\;\mu\text{m}$ ($1\text{--}2\;\mu\text{m}$, not merely $\lt 5\;\mu\text{m}$).
• Conclusion: Statements (A), (C), and (D) are correct.

Correct option: (3) (A), (C) and (D) only.

• Key Characteristics of Homogenized Milk:
• Production of Easily Digestible Soft Curd: The disruption of casein micelles and adsorption onto fragmented fat globules creates a loose, fragile coagulum upon rennet or acid action.
• Desirable Rheological Properties: Greatly increased viscosity, full-bodied mouthfeel, and enhanced whitening power in tea and coffee.
• Higher Susceptibility to Sunshine Flavor Defect: Because fat surface area is increased and milk proteins are dislodged, riboflavin (vitamin $B_2$) photosensitizes methionine into methional upon sunlight exposure, causing rapid oxidation.
• Cream Plug (A): Homogenization completely prevents the formation of cream plug or cream line.
• Conclusion: Statements (B), (C), and (D) are correct.

Correct option: (2) (B), (C) and (D) only.