The correct option is (c) 2 and 3 only.
Explanation
Pasteurization is a heat-treatment process used to destroy pathogenic microorganisms in certain foods and beverages, particularly milk, without significantly altering their taste or nutritional value.
Statement 1 is Incorrect: Pasteurization does not involve boiling milk at 100°C. Instead, milk is heated to a specific temperature below its boiling point. The standard methods are heating to about 72°C for 15 seconds (High-Temperature Short-Time or HTST) or 63°C for 30 minutes (Low-Temperature Long-Time or LTLT). Boiling at 100°C for an hour would denature proteins and destroy nutrients, which is distinct from pasteurization.
Statement 2 is Correct: A critical step in pasteurization is the rapid cooling (chilling) of the milk immediately after heating. This sudden temperature drop prevents the survival of thermoduric bacteria and inhibits the germination of spores, ensuring the milk remains safe for storage.
Statement 3 is Correct: The primary objective of this process is to kill harmful bacteria (pathogens) and reduce the population of spoilage organisms. By heating and subsequently chilling the milk, the process effectively prevents the growth of microbes, thereby extending the shelf life of the product.
Key Takeaway: Pasteurization involves heating milk to approximately 72°C for 15 seconds (or 63°C for 30 minutes) followed by rapid chilling to kill pathogens and prevent microbial growth, distinct from boiling.