Effect of Homogenization on Milk Viscosity

After homogenization, the viscosity of milk will:

Correct Answer: Increase

After homogenization, the viscosity of milk increases. Homogenization breaks down large fat globules into smaller ones (≤2 µm), dramatically increasing their total surface area. This means more fat–protein interaction, more resistance to flow, and thus higher viscosity.

Key Facts About Homogenization

• Homogenization creates a stable emulsion of milk serum and milk fat using a homogenizer.
• Fat globule size in homogenized milk: 2 microns (2 µm) (reduced from natural average of 2–5 µm).
• After homogenization, cream cannot be separated from milk by gravity.
• Viscosity increases because the increased surface area of smaller globules causes greater internal friction.

Contrast with Temperature Effect

• Temperature ↑ → viscosity decreases
• Homogenization → viscosity increases

Why Other Options Are Wrong

• Decrease → opposite is true; homogenization always increases viscosity.
• No change → the physical change in fat globule size directly affects viscosity.