1. : The main objective of thermal processing is to:
(A) Improve color
(B) Destroy microorganisms
(C) Enhance aroma
(D) Reduce viscosity
2. : Pasteurization was developed by:
(A) Louis Pasteur
(B) Robert Koch
(C) Isaac Newton
(D) Joseph Lister
3. : The process of heating foods at high temperature to kill spores is known as:
(A) Blanching
(B) Sterilization
(C) Pasteurization
(D) Evaporation
4. : The D-value in thermal processing represents:
(A) Decimal reduction time
(B) Doubling time
(C) Death rate
(D) Denaturation temperature
5. : The Z-value indicates:
(A) Time required to kill microbes
(B) Temperature change needed to change D-value by tenfold
(C) Pressure required for sterilization
(D) Energy absorbed during heating
6. : Commercial sterilization ensures destruction of:
(A) All microorganisms
(B) Pathogenic and spoilage microbes
(C) Only vegetative cells
(D) Yeasts only
7. : The F-value represents:
(A) Flow rate
(B) Heat resistance factor
(C) Time equivalent at a reference temperature
(D) Freezing point
8. : The thermal process that inactivates enzymes in vegetables before freezing is:
(A) Pasteurization
(B) Blanching
(C) Sterilization
(D) Drying
9. : Retort processing is usually carried out at:
(A) 100°C
(B) 121°C
(C) 80°C
(D) 60°C
10. : The microorganism used as an indicator for thermal process adequacy is:
(A) Bacillus subtilis
(B) Clostridium botulinum
(C) Salmonella typhi
(D) E. coli
11. : The term “cold point” in a can refers to:
(A) The coldest location in the can during heating
(B) The center of the can
(C) The point of sterilization
(D) The outer surface of the can
12. : Over-processing during canning may cause:
(A) Flavor improvement
(B) Texture softening
(C) Color enhancement
(D) Increased shelf life
13. : Which method is most suitable for low-acid foods?
(A) Boiling water processing
(B) Pressure canning
(C) Hot fill processing
(D) Open kettle
14. : Thermal death time (TDT) is the:
(A) Time to sterilize microorganisms at a specific temperature
(B) Time for product cooling
(C) Time to reach boiling
(D) Time to evaporate moisture
15. : The process of heating liquid foods followed by rapid cooling is:
(A) Retorting
(B) HTST pasteurization
(C) Blanching
(D) Cooking
16. : Spoilage in canned food due to hydrogen swells is caused by:
(A) Acid reaction with metal
(B) Air entry
(C) Microbial gas
(D) Improper seaming
17. : Which of the following is a low-acid food?
(A) Tomato juice
(B) Meat
(C) Pineapple
(D) Apple sauce
18. : Thermal processing of acid foods usually requires:
(A) Boiling water temperatures
(B) High-pressure steam
(C) Low-temperature storage
(D) Freezing
19. : The main purpose of double seaming in cans is to:
(A) Improve shape
(B) Prevent leakage
(C) Enhance color
(D) Reduce oxygen
20. : Which factor affects heat penetration during canning?
(A) Viscosity
(B) Color
(C) Packaging size only
(D) Shape
21. : The spoilage caused by thermophilic bacteria occurs mostly in:
(A) Frozen foods
(B) Canned foods
(C) Dried foods
(D) Dehydrated foods
22. : The primary heat transfer mode in conduction-heated foods is:
(A) Conduction
(B) Convection
(C) Radiation
(D) Diffusion
23. : Which process uses both conduction and convection heat transfer?
(A) Liquid soups
(B) Solid meats
(C) Dehydrated powders
(D) Nuts
24. : Acidified foods have a pH of:
(A) 7.0 or above
(B) 4.6 or below
(C) 6.5
(D) 9.0
25. : The main concern in processing low-acid canned foods is:
(A) Yeast growth
(B) Mold contamination
(C) Botulinum toxin formation
(D) Color fading
26. : The typical temperature range for pasteurization of milk is:
(A) 72°C for 15 sec
(B) 100°C for 5 sec
(C) 60°C for 1 min
(D) 121°C for 15 sec
27. : The process of cooling food immediately after heating is important to:
(A) Avoid overcooking
(B) Reduce spoilage
(C) Maintain texture
(D) All of the above
28. : The container used in retort processing must withstand:
(A) High pressure and temperature
(B) Cold temperature only
(C) UV light
(D) Dry air
29. : The term “thermal resistance” refers to:
(A) Resistance of microbes to heat
(B) Resistance of containers
(C) Air resistance
(D) Flow restriction
30. : HTST pasteurization stands for:
(A) High Temperature Short Time
(B) High Thermal Safe Treatment
(C) Heat Transfer Sterilization Type
(D) High Taste Short Treatment
31. : The time-temperature combination used in UHT processing is about:
(A) 121°C for 15 min
(B) 135–150°C for 1–2 sec
(C) 80°C for 10 min
(D) 70°C for 30 sec
32. : Which microorganism can survive pasteurization?
(A) Clostridium botulinum spores
(B) Yeasts
(C) Salmonella
(D) None
33. : The “come-up time” in thermal processing refers to:
(A) Cooling period
(B) Time to reach the required temperature
(C) Holding period
(D) Heating duration
34. : The purpose of pre-heating in canning is:
(A) Reduce air content
(B) Enhance sealing
(C) Sterilize the product
(D) All of the above
35. : The headspace in a can is provided to:
(A) Prevent bursting
(B) Allow expansion
(C) Aid heat transfer
(D) All of the above
36. : Which type of food requires the least heat treatment?
(A) High-acid foods
(B) Low-acid foods
(C) Neutral foods
(D) Protein-rich foods
37. : The primary mode of heat transfer in liquids is:
(A) Convection
(B) Conduction
(C) Radiation
(D) Adsorption
38. : The blanching process helps to:
(A) Fix color and texture
(B) Inactivate enzymes
(C) Remove gases
(D) All of the above
39. : The product inside a can continues to heat after removal from retort due to:
(A) Pressure
(B) Residual heat
(C) Reaction
(D) Conduction
40. : Spoilage caused by flat-sour bacteria produces:
(A) Gas formation
(B) Acid without gas
(C) Swollen cans
(D) Black discoloration
41. : Which of the following is not a thermal process?
(A) Blanching
(B) Freezing
(C) Pasteurization
(D) Sterilization
42. : The efficiency of heat penetration depends on:
(A) Product composition
(B) Container size
(C) Agitation
(D) All of the above
43. : Milk pasteurization destroys:
(A) Pathogenic bacteria
(B) All microorganisms
(C) Spores only
(D) Enzymes completely
44. : Overheating in thermal processing causes:
(A) Nutrient loss
(B) Browning
(C) Flavor change
(D) All of the above
45. : The temperature of 121°C is commonly achieved by using:
(A) Steam under pressure
(B) Boiling water
(C) Hot air
(D) Microwave heating
46. : Which vitamin is most sensitive to heat?
(A) Vitamin C
(B) Vitamin D
(C) Vitamin A
(D) Vitamin K
47. : Aseptic processing involves:
(A) Sterilizing product and package separately
(B) Heating package only
(C) Cold storage
(D) UV sterilization
48. : The principle of thermal preservation is based on:
(A) Time-temperature relationship
(B) Color
(C) Pressure
(D) Density
49. : The shelf life of thermally processed food mainly depends on:
(A) Storage temperature
(B) Packaging
(C) pH
(D) All of the above
50. : The main advantage of UHT processing is:
(A) Long shelf life without refrigeration
(B) Lower cost
(C) Reduced color
(D) Slow heating