Food Processing Unit Operations Multiple Choice Questions on “Drying – Moisture Content Determination Methods”.
1. _____________ is the amount of moisture a material will absorb relative to ambient temperature and humidity conditions.
a) Lyophilization
b) Hygroscopic action
c) Hydrophobic action
d) Hydrophilic action
Answer: b
Clarification: Hygroscopic action is the amount of moisture a material will absorb with respect to the temperature and humidity conditions. Due to hydroscopic action, the sample will continuously increase/ decrease in weight.
2. The measure of moisture content during thermogravimetric analysis is by the process of _________
a) water vaporization
b) freezing
c) oven drying
d) sun drying
Answer: a
Clarification: In thermogravimetric analysis, the moisture is determined by the loss of mass of a substance (normally moisture) when heated. This can be achieved by the water vaporization process. It is a complete, precise and approachable method to determine moisture.
3. Halogen and infrared drying are the examples of _________________
a) thermogravimetric analysis
b) freeze drying
c) non thermal analysis
d) pressure based analysis
Answer: a
Clarification: Halogen and infrared drying are the examples of thermogravimetric analysis. Halogen drying is up to twice as fast as traditional infrared technology. It is a complete, precise and approachable method to determine moisture.
4. The oven drying methodology consists of heating by ________
a) conduction
b) convection
c) radiation
d) both radiation and convection
Answer: b
Clarification: The most commonly used method for commercial purposes is oven drying methods for commercial purposes. The oven drying methodology consists of heating by convection. The demerits of this process are time and non-portability.
5. ______________ of moisture measurement is based on chemical reactions.
a) Lyophilization
b) Karl Fischer method
c) Halogen drying
d) Infrared drying
Answer: b
Clarification: Karl Fischer Method of moisture measurement is based on chemical reactions. A chemical reaction happens where the water is separated chemically from the rest of the sample. The water is then moved to other cell where it is measured. That measurement is equated with the initial mass of the sample and then moisture content is calculated.
6. _________ method id based on dielectric principle.
a) Electric moisture meter
b) Karl Fischer method
c) Lyophilization
d) Infrared drying
Answer: a
Clarification: Electric moisture meter method id based on dielectric principle. The electricity is measured by capacitance, conductance and radio frequency. They are inexpensive, easy to use and portable.
7. What is best method to use when the product have multiple layers that may have very different moisture levels?
a) Lyophilization
b) Karl Fischer method
c) Halogen drying
d) Microwave moisture meter
Answer: d
Clarification: Microwave moisture meter is best method to use when the product have multiple layers that may have very different moisture levels.In microwave method, the microwave is generally transmitted entirely through the samples.
8. Which one of the following is non-destructive moisture measurement?
a) Karl Fischer method
b) Nuclear moisture meter method
c) Loss on drying moisture method
d) Lyophilization
Answer: b
Clarification: In the Nuclear moisture meter technology, the energy is radiated into the sample and the amount of energy absorbed by the sample is measured. Beta radiation and gamma radiations are used for moisture determination. The relationship between absorbed energy and moisture content is then calculated to generate a calibration curve.
9. __________ uses reflectance & absorbance principles for calculating the moisture content.
a) Karl Fischer method
b) Nuclear moisture meter method
c) Loss on drying moisture meter method
d) Near infrared moisture meter method
Answer: d
Clarification: Near infrared moisture meter method uses absorbance and reflectance principles for determining the moisture content. This meter a beam of light on the product and then the light is filtered to a wavelength that excites the moisture molecules. The higher the amount of moisture content, higher is the amount of light absorbed.
10. The fundamental principle behind Karl Fischer method is based on the ____________
a) bunsen reaction on iodine in an aqueous medium
b) bunsen reaction between iodine and sulphuric acid in an aqueous medium
c) bunsen reaction between iodine and carbon dioxide in an aqueous medium
d) bunsen reaction between iodine and sulfur dioxide in an aqueous medium
Answer: d
Clarification: The fundamental principle behind Karl Fischer method is based on the bunsen reaction between iodine and sulfur dioxide in an aqueous medium where a primary alcohol like methanol is used as the solvent, and a base such as pyridine is used as the buffering agent.