Thermal processing is a common method for preserving liquid foods like milk and juice. The intensity of the heat treatment is chosen based on the desired shelf life and the need to preserve the food's sensory and nutritional qualities.
Step 1: Understanding the Question:
The question describes a specific thermal process: using high heat for a short time, with the goal of destroying pathogenic (disease-causing) microorganisms, not all microorganisms.
Step 2: Detailed Explanation:
Let's differentiate between the given processes:
(A) Sterilisation: This is a very severe heat treatment (e.g., UHT - Ultra High Temperature) designed to destroy all microorganisms, including heat-resistant bacterial spores. This results in a commercially sterile product with a long shelf life at room temperature.
(B) Pasteurisation: This is a milder heat treatment designed to kill pathogens and reduce the number of spoilage organisms. It does not eliminate all microbes, especially spores. The description "high heat for a short time" perfectly matches High-Temperature Short-Time (HTST) pasteurisation (e.g., 72$^\circ$C for 15 seconds for milk). The primary goal is safety while minimizing quality damage.
(C) Fermentation: This is a biochemical process that uses microorganisms to transform food, not a heat process to kill them.
(D) Dehydration: This is a preservation method that involves removing water, not applying heat to kill microbes directly.
The key distinction is that pasteurisation targets pathogens, while sterilisation targets all life forms. The question specifies destroying pathogens, making pasteurisation the correct answer.
Step 3: Final Answer:
The process described is Pasteurisation.