Step 1: Concept Overview:
The Clot on Boiling (COB) test is a quick method used in dairy plants to determine the heat stability of raw milk.
Step 2: In-Depth Explanation:
Fresh milk is normally heat-stable with a certain level of natural acidity. Improper storage allows bacteria to proliferate, converting lactose into lactic acid, increasing the "developed acidity."
Increased acidity (lower pH) destabilizes casein proteins. Boiling milk with high acidity causes protein coagulation, forming a clot. The COB test simply boils a small milk sample to observe this.
If the milk remains liquid after boiling, the test is negative (COB negative).
If clotting or curdling occurs, the test is positive (COB positive), indicating excessive developed acidity, making it unsuitable for heat treatments like pasteurization.
The COB test directly indicates developed acidity levels. Other tests are required to identify adulterants like urea, sugar, and bicarbonate.
Step 3: Conclusion:
The Clot on Boiling (COB) test identifies elevated developed acidity in milk.