This set of Fruits Processing Multiple Choice Questions & Answers (MCQs) focuses on “Factors Affecting Rate of Dehydration”.
1. Which of the following condition is represented through the phase diagrams?
a) Chemical conditions of a matter
b) Physical conditions of a matter
c) Electromagnetic conditions of a matter
d) Mechanical conditions of a matter
View Answer
Explanation: Physical conditions of a matter are represented through phase diagrams. It is a graphical depiction under different conditions of pressure and temperature. The x-axis represents the temperature and y-axis represents pressure.
2. At what temperature does critical point occurs in water?
a) 374°C
b) 91.85°C
c) -146°C
d) 132°C
View Answer
Explanation: The critical point of water occurs at 374°C. The critical point of propylene occurs at 91.85°C. The critical point of nitrogen occurs at -146°C. The critical point of ammonia occurs at 132°C.
3. Which of the following factors influences the drying rate?
a) Final moisture content
b) Pressure
c) pH
d) Composition of the product
View Answer
Explanation: Rate of drying is defined as the mass of water removed per unit time per unit area. It is influenced by composition of the product, initial moisture content, relative humidity of the product and process temperature, size and arrangement of stacking of the product.
4. What is the main driving force in heat transfer?
a) Temperature difference
b) Temperature and pressure difference
c) Concentration difference
d) Pressure difference
View Answer
Explanation: In heat transfer, the transfer of heat energy is due to the temperature difference. Generally the heat transfer takes place from higher temperature to lower temperature. This helps in attaining the equilibrium temperature in the product.
5. Drying process inactivate the enzyme.
a) True
b) False
View Answer
Explanation: The drying process removes the moisture content from the product. It slows down the enzymatic reactions. It does not completely destroy the enzyme. At a very high temperature the enzymes undergoes denaturation process and loses its three dimensional structure.
6. Which of the following is seen only as a phase change?
a) Latent heat
b) Specific heat
c) Enthalpy
d) Entropy
View Answer
Explanation: Latent heat is also called as heat of transformation or latent energy. Latent heat is defined as the absorption or removal of heat energy by a system at constant temperature normally first order phase transition. The effect is seen only as a phase change such as boiling of water and melting of ice.
7. At which stage of drying the water can be easily removed?
a) Transient early stage
b) Constant rate period
c) Rising rate period
d) Falling rate period
View Answer
Explanation: There are three major stages of drying in the drying curve. Transient early stage is the initial stage where the product heats up. It is called as transient period. Constant rate period is the next stage where moisture is relatively easy to remove from the product. Finally in falling rate period, the moisture is bound within the solid matrix.
8. Which of the following factors influence the drying behavior?
a) Porosity, hygroscopic properties
b) Porosity, homogeneity
c) Homogeneity, hygroscopic properties
d) Porosity, homogeneity, and hygroscopic properties
View Answer
Explanation: The drying behaviors of food materials can be determined by porosity of the food product, homogeneity in the composition of the food, and hygroscopic properties. Hygroscopic food materials move faster into the falling rate compared to the non-hygroscopic food materials.
9. Which of the following statements about drying rate are correct?
Statement 1: It depends on vapor pressure of water at drying temperature.
Statement 2: It depends on humidity in the external atmosphere.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: Rate of drying depends on the equilibrium vapor pressure of water present in the food. It also depends on the moisture of the food. Vapor pressure of water at drying temperature plays a major role in drying rate. It depends on the vapor pressure in the external environment.
10. Which of the following statements about drying process are correct?
Statement 1: It depends on latent heat of vaporization.
Statement 2: It does not transport any moisture.
a) True, False
b) True, True
c) False, True
d) False, False
View Answer
Explanation: In drying process the latent heat of vaporization is important as it converts moisture which is in liquid into vapor. The moisture is transported out from the food during drying process in order to obtain dehydrated product.
11. Which of the following component acts as an independent factor in constant rate period?
a) Moisture content
b) Temperature
c) Pressure
d) Humidity
View Answer
Explanation: In the rate of drying curve, the moisture content is an independent factor seen in the constant rate period. During this period, diffusion of moisture takes place. The droplet maintains saturated surface conditions which help in evaporation at constant rate.
12. Which of the following mechanism is observed in drying constant?
a) Heat and mass transport phenomena
b) Heat phenomena
c) Mass transport phenomena
d) Drying phenomena
View Answer
Explanation: The mechanism observed in drying constant is heat and mass transport phenomena. It influences the process variables that exert on process to remove the moisture. Drying constant is done by trial studies where it is calculated from the amount of moisture content removed versus time at various drying conditions.
13. At what stage the drying rate curve declines?
a) Transient early stage
b) Constant rate period
c) Rising rate period
d) Falling rate period
View Answer
Explanation: The point at which the drying rate curve declining from constant drying period is known as critical moisture content. It is defined as the average material moisture content at which the drying rate begins to decrease. In constant rate period, the moisture is easily removed from the product.
14. Who coined the term latent heat?
a) Rudolf Clausius
b) Thomas Young
c) Joseph Black
d) Evangelista Torricelli
View Answer
Explanation: Joseph Black invented the term latent heat. Thomas Young invented the term enthalpy. The barometer is invented by Evangelista Torricelli. Rudolf Clausius invented the term entropy.
15. Does boiling point decrease with pressure?
a) True
b) False
View Answer
Explanation: At higher altitudes, the atmospheric pressure is lower compared to the plains. Therefore the boiling point is also lower at higher altitude. It depends on pressure up to the critical point. Boiling point is directly proportional to the pressure. So the boiling point does not decrease but increases with the pressure.
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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