Vegetables Processing Questions and Answers – Drying of Vegetables: Principles and Dryer Design

This set of Vegetables Processing Multiple Choice Questions & Answers (MCQs) focuses on “Drying of Vegetables: Principles and Dryer Design”.

1. What is the importance of dry vegetables?
a) Less space requirement
b) No microbial growth
c) Easy to transport
d) Less space requirement, no microbial growth and easy to transport
View Answer

Answer: d
Explanation: Vegetables can be easily dried. Since vegetables contain less acid than fruits. It is normally dried till they are brittle. When correctly dried, they should contain only 10% moisture content. At this level no microorganisms can grow.

2. What are the characteristics of dried vegetables?
a) Increase in moisture content
b) Decrease in moisture content
c) No affect in moisture content
d) Increase in water activity
View Answer

Answer: a
Explanation: The dehydrated vegetables should have the low moisture content, absence of defects which can be caused by the use of unsuitable raw material. It should have quick and acceptable re-hydration process. It should take up the shape and original form of the product before its drying.

3. What is the moisture content of a dried vegetable?
a) Less than 5%
b) Less than 10%
c) Less than 15%
d) Less than 12%
View Answer

Answer: a
Explanation: The moisture content of the dehydrated vegetables should be less than 5%. The dehydration preserves the vegetable because it reduces its moisture content. Therefore it avoids or limits the microorganism growths and chemical reactions.

4. What is the effect on enzymes during drying process?
a) Increase the action of enzyme
b) Slows down the action of enzyme
c) No effect on the action of enzyme
d) Acts as catalysts
View Answer

Answer: b
Explanation: Drying eliminates the moisture from the food so that the yeast, bacteria and mold cannot grow and spoil the product. Drying also decelerates the enzymatic action but it does not inactivate them. The drying process removes moisture so that the food becomes smaller and lighter in weight.

5. Can you rehydrate dried onions?
a) True
b) False
View Answer

Answer: a
Explanation: Dried onions can be rehydrated by using water. To rehydrate, simply soak the product in warm water for about 15 minutes, then drain. Once they’re rehydrated, they are used as a flavorful substitute for fresh onions.

6. How long will dehydrated carrots last?
a) 1 month
b) 2 months
c) 3 months
d) 15 days
View Answer

Answer: c
Explanation: Unblanched dehydrated carrots will last about 3 months before their quality noticeably deteriorates. It shod be stored under hygienic conditions. As there is no water available, microbes cannot grow on them.

7. What is the principle of fluidized bed dryer work?
a) Fluidization
b) Crystallization
c) Dehydration
d) Rehydration
View Answer

Answer: a
Explanation: Fluidization is the principle behind the working of fluid bed dryers. It is a process where a material is transformed from a static solid state to a dynamic fluid state. In this process, air and hot gas are introduced through a plate with perforation that is transferred into the material cabin.

8. What is the merit of fluid bed dryers?
a) Suitable for heat sensitive products
b) Suitable for low acid products
c) Suitable for high acid products
d) Suitable for high viscosity products
View Answer

Answer: a
Explanation: Fluidized bed dryers guarantee fast and homogeneous drying. Fluid bed dryer is suitable for heat sensitive products. Fluidized bed ensures efficiency in material drying. Handling fluidized bed dryer is easy and less labor intensive.

9. Which condition is highly critical for drying operation?
a) Equilibrium water sorption isotherms
b) Equilibrium water adsorption isotherms
c) Equilibrium water absorption isotherms
d) Equilibrium isotherms
View Answer

Answer: a
Explanation: Equilibrium water sorption isotherms are important in drying operations. It is important because they indicate how dry a solid can become if it is brought into contact with air of a given relative humidity. This relationship between water activity and moisture content at a given temperature is called the moisture sorption isotherm.

10. What are the factors affecting drying?
a) Vapor pressure and relative humidity
b) Vapor pressure
c) Relative humidity
d) Size of the equipment
View Answer

Answer: c
Explanation: Factors affecting drying are vapor pressure and relative humidity. The moisture movement within the wood will also affect the drying rate. The influence of temperature on drying rate, air circulation plays an important role in drying.

11. Which of the following vegetable can be used in drum drier?
a) Potato
b) Tomato
c) Spinach
d) Coriander
View Answer

Answer: a
Explanation: Mainly starchy products can easily form a film. For example beans and potatoes are dried with a drum dryer. It is a contact dryer. The dried material is separated from the heating source with a metal wall.

12. Which of the following heat transfer takes place in tray drier?
a) Conduction
b) Convection
c) Radiation
d) Conduction and radiation
View Answer

Answer: b
Explanation: Tray drying uses convective heat and mass transfer process. It is commonly used to separate solids from liquids in industries. In this drying, a stream of hot air/gas is passed over a moist solid to evaporate the liquid. This process does not require agitation. It allows for control over temperature and other properties.

13. What is the process of drying?
a) Mass transfer process
b) Heat transfer process
c) Mass and heat transfer process
d) Does not have any transfer process
View Answer

Answer: a
Explanation: Drying is generally a mass transfer process. Drying removes water or other solvent by vaporization from a liquid, solid or semi solid. A heat source and an agent are required to eliminate the vapor produced by the drying process.

14. Drying and evaporation are same process.
a) True
b) False
View Answer

Answer: b
Explanation: Drying is the removal of water from a substance. For example water or the moisture is removed from fruits and vegetables. Evaporation is the change of liquid state to gaseous state. For example on boiling water, the water gets evaporated and turns into vapor.

Sanfoundry Global Education & Learning Series – Vegetables Processing.

To practice all areas of Vegetables Processing, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & discussions at Telegram SanfoundryClasses.