Question

Homogenized milk is whiter in colour due to the increased level of

• A. Absorption of light
• B. Reflection of light
• C. Dispersion of light
• D. Scattering of light

Hint:

Optical Properties of Homogenized Milk: Increased Whiteness is caused by INCREASED SCATTERING OF LIGHT due to millions of subdivided submicron fat globules and casein fragments.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Colloidal optics and Mie light scattering: high-pressure homogenization disintegrates fat globules into submicron particles ($< 1 - 2\ \mu ext{m}$), increasing the fat-water interfacial surface area by 6- to 10-fold and dramatically increasing diffuse Mie light scattering to impart a brilliant white, opaque appearance.
Key Formula or Approach:
\[ \text{High Pressure Homogenization: } d_{\text{average}} (3 - 4\;\mu\text{m} \rightarrow < 1\;\mu\text{m}) \implies \text{Interfacial Area } \uparrow 10\times \implies \mathbf{Diffuse \text{ } Light \text{ } Scattering } (I_{\text{scattered}}) \uparrow \]

Step 2: Detailed Explanation:
In milk optical physics and homogenization technology:
- The natural opaque white color of milk is primarily an optical phenomenon caused by the Diffuse Scattering of Visible Light by suspended colloidal casein micelles and emulsified milk fat globules.
- When whole milk is subjected to High-Pressure Homogenization ($15 - 20\text{ MPa}$):
1. Large native fat globules (average diameter $3 - 4\;\mu\text{m}$) are mechanically disrupted into billions of tiny submicron fat droplets ($< 1\;\mu\text{m}$).
2. The total fat surface area increases 6- to 10-fold and becomes coated with thousands of casein submicelles.
3. This enormous multiplication of optical refractive interfaces dramatically increases the Scattering of Light (D) across all visible wavelengths, making homogenized milk appear significantly whiter, more opaque, and creamier in color.

Step 3: Final Answer:
Hence, homogenized milk is whiter due to increased Scattering of light, corresponding to option (D).