This set of Food Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Water and Ice – Moisture Sorption Isotherms”.
1. Which of the following is expressed as mass of water per unit mass of dry material?
a) Sorption
b) Relative vapour pressure
c) Hysteresis curve
d) Moisture sorption isotherm
View Answer
Explanation: A plot of water content of a food versus p/pO at constant temperature is known as moisture sorption isotherm. It is expressed as mass of water per unit mass of dry material.
2. How many zones are there in a moisture sorption isotherm?
a) 5
b) 4
c) 3
d) 2
View Answer
Explanation: Water is added (resorption), sample composition moves from zone1 (dry) to zone3 (high moisture) and the properties of water associated with each zone differ significantly.
3. The most strongly sorbed and least mobile water is present in which zone of the isotherm?
a) Zone 1
b) Zone 2
c) Zone 3
d) Zone 4
View Answer
Explanation: Water present in zone1 of the isotherm is most strongly sorbed and least mobile. This water associates with accessible
4. The graph of a water loss of a fresh product is called what?
a) Desorption curve
b) Absorption curve
c) Adsorption
d) Hysterysis
View Answer
Explanation: The phenomenon whereby a substance is released from or through a surface. The process is the opposite of sorption. The graph of a water loss of a fresh product is called desorption curve.
5. The graph of the water absorption of a dried product is called what?
a) Desorption curve
b) Absorption curve
c) Adsorption
d) Hysteresis
View Answer
Explanation: The graph of the water absorption of a dried product is called absorption curve. It charts data regarding the degree of intensity to which varying light waves are absorbed.
6. The gap between absorption and desorption curve is called?
a) Desorption curve
b) Absorption curve
c) Adsorption
d) Hysteresis
View Answer
Explanation: Hysteresis is the phenomenon in which the value of a physical property lags behind changes in the effect causing it, as for instance when magnetic induction lags behind the magnetizing force.
7. What causes the hysteresis between adsorption isotherms and desorption isotherm?
a) Percolation theory
b) Adsorption theory
c) Desorption theory
d) Newton’s theory
View Answer
Explanation: The hysteresis between adsorption isotherm and desorption isotherm is caused by the gradual desorption mechanism (percolation theory) due to the different size pores to be combined. This percolation theory suggests that the pore size distribution obtained from the desorption isotherm is problematic to be used.
Sanfoundry Global Education & Learning Series – Food Chemistry.
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