This set of Dairy Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Physical Properties of Milk”.
1. Opacity in milk is due to which of the following reasons?
a) White color
b) Heat treatment
c) Additives
d) Suspended particles of fat
View Answer
Explanation: The opacity of milk is due to its content of suspended particles of fat, proteins and certain minerals. Heat treatment has no effect on opacity.
2. Yellowish tinge in milk can be attributed to which of the following?
a) Carotene
b) Water
c) Riboflavin
d) Metalin
View Answer
Explanation: The color varies from white to yellow according to the coloration (carotene content) of the fat. This is also the main reason behind the yellow color of the butter.
3. In an equation Fat%, SNF% and water determine‘d’. The‘d’ in this expression is?
a) Viscosity
b) Friction force
c) Density
d) Acceleration
View Answer
Explanation: The d is the density of milk at the temperature 15.5℃.Density is basically the degree of compactness of the substance.
4. Calculate the density of milk at 15.5℃ having 3.2% fat and 8.5% SNF.
a) 2.03 g/cm3
b) 1.03 g/cm3
c) 4.03 g/cm3
d) 5.03 g/cm3
View Answer
Explanation: Density of milk at 15.5℃ having 3.2% fat and 8.5% SNF is 1.03 g/cm3. It can be calculated using the formula.
5. Milk is ______ with blood.
a) Hypertonic
b) Hypotonic
c) Isotonic
d) No pressure
View Answer
Explanation: Milk is isotonic with blood. Isotonic denoting or relating to a solution having the same osmotic pressure as some other solution, especially one in a cell or a body fluid.
6. Osmotic pressure is controlled by the number of molecules or particles, not the weight of solute.
a) True
b) False
View Answer
Explanation: Osmotic pressure is controlled by the number of molecules or particles, not the weight of solute; thus 100 molecules of size 10 will have 10 times the osmotic pressure of 10 molecules of size 100.
7. Define the temperature at which a liquid turns into a solid when cooled.
a) Boiling point
b) Melting point
c) Freezing point
d) Evaporation temperature
View Answer
Explanation: The temperature at which a liquid turns into a solid when cooled is called freezing point. The Freezing point of milk is closer to 0℃.
8. Freezing point helps to check which of the following adulteration in milk?
a) Sugar adulteration
b) Water adulteration
c) Gas adulteration
d) Color adulteration
View Answer
Explanation: The freezing point of milk is the only reliable parameter to check for adulteration with water. The freezing point of milk from individual cows has been found to vary from –0.54 to –0.59°C.
9. The acidity of a solution is dependent on which of the following?
a) Water content
b) Fat content
c) Acid content
d) [H+] ions
View Answer
Explanation: The acidity of a solution depends on the concentration of hydronium ions [H+] in it. When the concentrations of [H+] and [OH–] (hydroxyl) ions are equal, the solution is called neutral.
10. What does pH of the solution represent?
a) Solubility
b) Osmotic pressure
c) Hydronium ion concentration
d) Water content
View Answer
Explanation: The pH represents the hydronium ion concentration of a solution and can mathematically be defined as the negative logarithm of the hydronium ion [H+] concentration.
11. pH of normal milk is _____ at 25℃.
a) 4
b) 4.3
c) 6.6
d) 9
View Answer
Explanation: Normal milk is a slightly acid solution with a pH falling between 6.5 and 6.7 with 6.6 the most usual value. The temperature of measurement near 25°C.
12. In determining acidity, the solution in the burette is?
a) Hydrochloric acid
b) Potassium salt
c) Potash alum
d) Sodium Hydroxide solution
View Answer
Explanation: The blue liquid present in the burette in this picture is a NaOH solution. NaoH is a basic solution.
13. Titratable acidity of milk cannot be expressed in which of the following degree?
a) ᵒSH
b) ᵒTh
c) ᵒD
d) ℃
View Answer
Explanation: °SH = Soxhlet Henkel degrees, °Th = Thörner degrees; °D = Dornic degrees, all three can be used to express titratable acidity.
14. 1.7 ml of N/10 NaOH is required for titration of a 10 ml sample of milk. Compute the titratable acidity.
a) .17 °Th
b) 170 °Th
c) 17 °Th
d) 10 °Th
View Answer
Explanation: 10 x 1.7 = 17 ml would therefore be needed for 100 ml, and the acidity of the milk is consequently 17 °Th.
15. The first milk that a cow produces after calving is called ________
a) Cream
b) Butter
c) Colostrum
d) High fat milk
View Answer
Explanation: The first milk that a cow produces after calving is called Colostrum. Colostrum has brownish-yellow color, peculiar smell and a rather salty taste. The content of catalyzes and peroxidase is high.
Sanfoundry Global Education & Learning Series – Dairy Engineering.
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