Casein Precipitation pH for Paneer

Paneer is made by coagulating milk proteins. The primary protein in milk is casein. Casein molecules have different charges depending on the pH of the milk.

Understanding Casein Isoelectric Point

Each protein has an isoelectric point (pI), which is the pH at which the protein carries no net electrical charge. For casein, the isoelectric point is approximately pH 4.6.

Mechanism of Precipitation

• When milk is acidified, the pH decreases.
• As the pH approaches the isoelectric point (pH 4.6), the net charge on the casein micelles becomes zero.
• At this point, the repulsive forces between casein molecules are minimized, allowing them to aggregate and form a solid mass (curd).
• This aggregation is essential for paneer preparation.

Conclusion on Precipitation pH

Therefore, casein precipitates most effectively at its isoelectric point, which is pH 4.6. This is the critical pH value targeted when using acid (like lemon juice or vinegar) to make paneer from milk.