Question

Why is a starter culture added to set the milk to curd? Explain?

Answer 1

Hint: When a small amount of starter culture is added to the milk, it gets converted into curd. The sour taste of the curd is imparted by this process. Cheese, paneer, and sour cream are some of the dairy products which are made by the addition of starter culture.

Complete answer
Milk is converted to curd by a process called bacterial fermentation. The starter culture, also known as the inoculum is added to curdle the milk. The lactobacillus is a gram-positive, anaerobic bacterium that converts lactose present in the milk to lactic acid and will digest the milk protein known as casein to make the curd. The lactic acid contributes to the sour taste in the curd and enhances the nutritional value of the curd by escalating the amount of vitamin B12.

Additional information
- Lactobacillus is the biggest group of lactic acid bacteria. It forms a substantial part of the microbiota present in our body.
- The lactic acid generated in the curd will reduce the milk pH and thus curdles the milk.
- Lactobacillus aid in the breakdown of the food, nutrient absorption, and helps in the prevention of diarrhea.
- The lack of lactase enzyme in the body results in lactose intolerance, a condition where the person cannot digest lactose. Lactose intolerant people cannot consume dairy products that have lactose.
Nowadays, probiotic curd is available which can be consumed by a lactose intolerant person.

Note: Bacterial fermentation is defined as the process by which bacteria will break organic compounds into simpler substances by anaerobic respiration. Lactobacillus bacteria make curd and yogurt is prepared by particular bacterial strains called bulgaricus and streptococcus species.