Thermal processing (pasteurization, sterilization) MCQs Food science December 27, 2025August 2, 2024 by u930973931_answers 35 min Score: 0 Attempted: 0/35 Subscribe 1. What is the main purpose of pasteurization? (A) Enhance flavor (B) Improve texture (C) Kill harmful microorganisms (D) Increase shelf life 2. Which temperature and time combination is typical for High-Temperature Short-Time (HTST) pasteurization? (A) 85°C for 1 second (B) 63°C for 30 minutes (C) 72°C for 15 seconds (D) 100°C for 10 minutes 3. Which of the following is a common method of sterilization in food processing? (A) Autoclaving (B) Drying (C) Freezing (D) Salting 4. Which microorganism is most resistant to thermal processing? (A) E. coli (B) Salmonella (C) Listeria (D) Bacillus spores 5. Ultra-high temperature (UHT) processing typically heats the product to: (A) 121°C for 15 minutes (B) 72°C for 15 seconds (C) 85°C for 10 minutes (D) 135-150°C for 2-5 seconds 6. Which of the following is a benefit of pasteurization? (A) Complete sterilization (B) Increased shelf life (C) Reduced nutritional content (D) Enhanced flavor 7. What is the main difference between pasteurization and sterilization? (A) Sterilization aims to eliminate all forms of life (B) Pasteurization eliminates all microorganisms (C) Sterilization uses lower temperatures (D) Pasteurization enhances flavor more than sterilization 8. Which of the following temperatures is used for batch pasteurization? (A) 63°C (B) 85°C (C) 72°C (D) 100°C 9. In UHT processing, the product is typically packaged in: (A) Metal cans (B) Aseptic containers (C) Glass jars (D) Plastic bags 10. Which of the following is a potential drawback of thermal processing? (A) Increased microbial load (B) Improved taste (C) Reduced nutritional quality (D) Increased shelf life 11. Sterilization typically involves heating food to a temperature of: (A) 72°C (B) 63°C (C) 85°C (D) 121°C 12. The main objective of pasteurization in milk is to: (A) Extend shelf life indefinitely (B) Eliminate all bacteria (C) Destroy pathogenic microorganisms (D) Enhance flavor 13. Which process involves heating food at 63°C for 30 minutes? (A) HTST pasteurization (B) Batch pasteurization (C) UHT processing (D) Sterilization 14. Thermal death time refers to: (A) The time required to freeze microorganisms (B) The duration of the cooling process (C) The time needed to reach boiling point (D) The time required to kill microorganisms at a specific temperature 15. Which of the following is a characteristic of UHT milk? (A) Requires refrigeration before opening (B) Short shelf life (C) Extended shelf life at room temperature (D) Less stable than pasteurized milk 16. What is the primary advantage of UHT processing over traditional pasteurization? (A) Lower processing costs (B) Better nutritional retention (C) Improved taste (D) Longer shelf life without refrigeration 17. Which of the following organisms is commonly used as an indicator for the effectiveness of sterilization? (A) E. coli (B) Clostridium botulinum spores (C) Listeria (D) Salmonella 18. What does D-value refer to in thermal processing? (A) The rate of microbial growth (B) The temperature needed to kill all microorganisms (C) The duration of the pasteurization process (D) The time required to kill 90% of the microorganisms at a specific temperature 19. Which of the following is a common application of thermal sterilization? (A) Preservation of canned foods (B) Fermentation of dairy products (C) Baking of bread (D) Freezing of vegetables 20. In thermal processing, what does the term “F-value” signify? (A) The sterilization time at a specific temperature (B) The thermal resistance of the target microorganism (C) The temperature of pasteurization (D) The cooling time 21. What is the main purpose of using a retort in food processing? (A) To freeze food (B) To ferment food (C) To dry food (D) To sterilize food 22. Which of the following is true about low-temperature long-time (LTLT) pasteurization? (A) It has a longer processing time (B) It uses a higher temperature than HTST pasteurization (C) It is faster than HTST pasteurization (D) It is used for UHT processing 23. Thermal processing aims to inactivate which of the following? (A) Enzymes (B) Both a and b (C) Pathogenic microorganisms (D) None of the above 24. Which process is designed to destroy all forms of microbial life, including spores? (A) Pasteurization (B) Sterilization (C) Refrigeration (D) Freezing 25. Which of the following is a disadvantage of high-temperature processing? (A) Reduced microbial load (B) Longer shelf life (C) Increased flavor (D) Nutrient loss 26. Which type of pasteurization is most commonly used for milk? (A) UHT processing (B) HTST pasteurization (C) Batch pasteurization (D) Sterilization 27. What is the effect of thermal processing on enzyme activity in food? (A) Inhibits enzyme activity (B) Enhances enzyme activity (C) No effect (D) Depends on the enzyme 28. Which of the following factors affects the heat resistance of microorganisms? (A) All of the above (B) pH (C) Composition of the food (D) Water activity 29. Which method of thermal processing is least likely to affect the sensory characteristics of food? (A) UHT processing (B) Batch pasteurization (C) Sterilization (D) HTST pasteurization 30. In canning, what is the primary purpose of thermal processing? (A) Enhance flavor (B) Destroy spoilage microorganisms (C) Improve texture (D) Reduce production costs 31. What is the typical temperature range for UHT processing? (A) 63-72°C (B) 72-85°C (C) 135-150°C (D) 85-100°C 32. Which of the following is a common indicator microorganism used in the dairy industry to evaluate the effectiveness of pasteurization? (A) Escherichia coli (B) Listeria monocytogenes (C) Coxiella burnetii (D) Clostridium botulinum 33. Which thermal processing method uses steam under pressure? (A) Batch pasteurization (B) Sterilization (C) HTST pasteurization (D) UHT processing 34. What is the primary benefit of using aseptic packaging with UHT processing? (A) Enhanced flavor (B) Improved texture (C) Reduced processing time (D) Extended shelf life without refrigeration 35. In the context of food safety, what does the term “commercial sterility” mean? (A) Elimination of all pathogens and spoilage microorganisms under normal storage conditions (B) Complete elimination of all microorganisms (C) Reduction of microbial load to safe levels (D) Pasteurization of high-acid foods