Q.How is milk converted into curd? Explain the process of curd formation.

Step 1. A small amount of curd is added to fresh, warm milk (below about 40 degrees C) as a starter or inoculum; this starter contains millions of live Lactobacillus (lactic acid bacteria, LAB) cells.

Step 2. Under the suitable warm temperature, these LAB multiply rapidly in the milk, using the milk sugar (lactose) as their substrate and fermenting it to lactic acid as their metabolic product.

Step 3. The accumulating lactic acid lowers the pH of the milk, which causes the milk protein casein to denature and coagulate — this coagulation is what curdles the liquid milk into the semi-solid curd. …

Trace the starter-inoculation, LAB fermentation and casein-c …

• Describing curd formation as simple souring without naming the specific bacteria or the casein-coagulation mechanism. …