This set of Food Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Water Activity and Relative Vapour Pressure”.
1. The measure of the availability of water molecule to enter into microbial, enzymatic or chemical reaction is called what?
a) Dipole moment
b) Ionic interaction
c) Hydration
d) Water activity
View Answer
Explanation: Water activity is the measure of availability of water molecule to enter into microbial, enzymatic or chemical reaction. It is represented as aw.
2. What happens when the % of bound water in food increases?
a) aw increases
b) No change
c) aw decreases
d) Ionic interaction increases
View Answer
Explanation: Bound water is a form of water. It is inversely related to water activity. when the % of bound water in food increases automatically aw decreases.
3. Name the instrument used to measure vapour pressure.
a) Barometer
b) Manometer
c) Thermometer
d) Seismograph
View Answer
Explanation: The instrument used to measure vapour pressure is called as manometer. They are often measured in millibars. The gauge used to measure atmospheric pressure is called barometer
4. What is the water activity of pure water?
a) 1
b) 8
c) 5
d) 3
View Answer
Explanation: Water activity is the measure of availability of water molecule to enter into microbial, enzymatic or chemical reaction. The water activity of pure water is 1.
5. How much % of moisture present in stable potato starch?
a) 50%
b) 20%
c) 60%
d) 80%
View Answer
Explanation: Some foods are stable at low moisture content whereas others at high moisture content. Peanut oil deteriorates at a moisture content of above 0.6% whereas potato starch stable at 20% moisture content.
6. What is the relation between water activity and growth of microorganisms?
a) Increased aw
b) No change
c) Decreased aw
d) Ionic interaction increases
View Answer
Explanation: Decreased aw retards the growth of microorganisms, slows enzyme catalyzed reactions and retards non enzymatic browning.
7. What happens when water activity of food decreases?
a) Improving shelf life of food
b) Spoilage of food
c) Faster spoilage of food
d) More contamination by pathogens
View Answer
Explanation: Decreasing water activity improves the shelf life of food. It is by the use of additives with high water binding capacity.
Sanfoundry Global Education & Learning Series – Food Chemistry.
To practice all areas of Food Chemistry, here is complete set of Multiple Choice Questions and Answers.
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