This set of Fruits Processing Multiple Choice Questions & Answers (MCQs) focuses on “Ultra High Temperature Processing”.
1. What is the full form of UHT?
a) Ultra high temperature
b) Unique handling transport
c) Ultra high time
d) Universal handling transport
View Answer
Explanation: The full form of UHT is ultra-high temperature. The higher processing temperatures for a shorter time are possible if the product is sterilized before is filled into a pre-sterilized containers in a sterile atmosphere. Continuous flow of heat at a temperature of 135⁰C for a very short time of 2 to 5 seconds destruct almost all the microorganisms and spores present in the food.
2. What is purpose of ultra-high temperature (UHT) processing?
a) To achieve a longer shelf life
b) To filter all heat resistant spore forming bacteria
c) To activate enzymes
d) To provide profits
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Explanation: The purpose of UHT processing is to achieve a longer shelf life. It also kills all heat resistant spore forming bacteria. It inactivates enzymes. For example, it inactivates pectinol and filtragol used in processing of beverages. It is also used in inactivation of yeasts.
3. What are two methods to perform ultra-high temperature (UHT) processing?
a) Direct heating, evaporative heating
b) Indirect heating, evaporative heating
c) Direct heating, indirect heating
d) Direct heating, vacuum heating
View Answer
Explanation: The two methods to perform ultra-high temperature (UHT) processing are direct heating and indirect heating. Direct heating systems is the system where the high temperature steam is directly applied to the food material under strict controlled conditions. Indirect heating system is a system where a partition placed between food product and steam or refrigerant.
4. Which of the following is not a direct heating system in UHT processing?
a) Injection
b) Infusion
c) Electric heating
d) Tubular heat exchanger
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Explanation: Tubular heat exchanger is an indirect heating system. Injection, infusion and electric heating are direct heating system. It consists of a pair of concentric tubes. For ease of cleaning, the food product usually flows in the inner tube and the heating or cooling medium in the outer annular space.
5. Which of the following is not an indirect heating system in UHT processing?
a) Plate heat exchanger
b) Scraped surface exchanger
c) Electric heating
d) Tubular heat exchanger
View Answer
Explanation: Electric heating is a direct heating system. I Plate heat exchanger, scraped surface exchanger and tubular heat exchanger are indirect heating system. Electric current is directly passing through the food products. This system is applicable for liquid foods.
6. Which of the following method is an instant heating and cooling process?
a) Injection
b) Infusion
c) Electric heating
d) Tubular heat exchanger
View Answer
Explanation: Infusion method is an instant heating and cooling process. Localized over heating is not applicable and highly suitable for low and high viscous food products. The product is pumped through a distributing nozzle into a chamber of steam with high pressure. Immediately after processing, flash cooling is applied to the food product in a vacuum chamber.
7. Which of the following method uses steam injectors?
a) Injection
b) Infusion
c) Electric heating
d) Tubular heat exchanger
View Answer
Explanation: Injection is a process where high pressure steam is directly applied into the food product by steam injector which raises the temperature rapidly. Then the food product is flash cooled in a vacuum. This method is energy intensive and cause flavor damage.
8. Are these statements about the plate heat exchanger true?
Statement 1: It has high flexibility.
Statement 2: Difficult to clean.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: The advantage of the plate heat exchangers is it has high flexibility. The capacity can be increased or decreased by adding or removing plates. By opening the stack, both sides of the entire exchange area are made accessible for cleaning and inspection. High heat transfer coefficient, due to increased turbulence in the narrow flow channel.
9. What is the disadvantage of using plate heat exchanger?
a) High pressure drop
b) Requires more energy
c) Requires more space
d) High maintenance
View Answer
Explanation: Disadvantage of the plate heat exchangers is the narrow size of the flow channels. This result in high pressure drops. It limits its use to low viscosity fluids not containing large suspended particles. The need for gaskets is also a disadvantage.
10. Which of the following equipment is used for high viscous product?
a) Plate heat exchanger
b) Scraped surface exchanger
c) Electric heating
d) Tubular heat exchanger
View Answer
Explanation: Scraped surface heat exchangers are used for heating and cooling highly viscous fluids and for slush-freezing. Continuous ice cream freezers and slush freezers are essentially scraped surface heat exchangers with a refrigerant evaporating in the jacket. The scraped surface exchanger is an expensive piece of equipment, both in price and in operating cost.
11. The D value of the UHT process is high.
a) True
b) False
View Answer
Explanation: The D value of the ultra-high temperature (UHT) process is high. Therefore the microbes are destroyed. The shelf life of the product is also increased. The Z value is also higher for quality factors than the microorganisms.
12. What are the irreversible changes takes place during UHT process?
a) Vitamin content changes
b) ATP production
c) ADP production
d) Energy metabolism
View Answer
Explanation: Vitamins are not heat stable components. Therefore, under high temperature the vitamin profile may vary from the original product. In some cases, fat globule composition is also altered. The maillard reaction and the non-enzymatic browning reaction take place in carbohydrate rich products.
Sanfoundry Global Education & Learning Series – Fruits Processing.
To practice all areas of Fruits Processing, here is complete set of 1000+ Multiple Choice Questions and Answers.
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