Engineering Questions with Answers - Multiple Choice Questions
Primary Production of Milk Engineering MCQs
1 - Question
Name the scientist who invented Homogenization?
a) Pasteur
b) Rutherford
c) Leuwenhoek
d) Gaulin
View Answer
Explanation: Gaulin, who invented the process of homogenization in 1899, described it in French as “fixer la composition des liquids”.
2 - Question
Disruption of fat globules into much smaller fat globules is defined as?
a) Standardization
b) Centrifugation
c) Homogenization
d) Chilling
View Answer
Explanation: Homogenization has become a standard industrial process, universally practiced as a means of stabilizing the fat emulsion against gravity separation. Homogenization primarily causes disruption of fat globules into much smaller ones.
3 - Question
Disintegration of fat globules in homogenization is achieved by which of the following?
a) Turbulence
b) Cavitation
c) Turbulence and cavitations
d) Pasteurization
View Answer
Explanation: The disintegration of the original fat globules is achieved by a combination of contributing factors such as turbulence and cavitations. The net result reduces the fat globules to approximately 1mm in diameter.
4 - Question
Cream with higher fat content than ____ cannot normally be homogenized at the normal high pressure.
a) 5%
b) 10%
c) 12%
d) 15%
View Answer
Explanation: Cream with higher fat content than 12 % cannot normally be homogenized at the normal high pressure because clusters are formed as a result of lack of membrane material (casein). A sufficiently good homogenization effect requires approximately 0.2 g casein per g of fat.
5 - Question
Homogenization of cold milk is ineffective.
a) True
b) False
View Answer
Explanation: Homogenization of cold milk, in which the fat is essentially solidified, is virtually ineffective. Processing at temperatures conducive to the partial solidification of milk fat (i.e. 30 – 35°C) results in incomplete dispersion of the fat phase.
6 - Question
Homogenization temperature applied normally are ________
a) 30- 40℃
b) 50- 60℃
c) 60- 70℃
d) 90-100℃
View Answer
Explanation: Homogenization temperatures normally applied are 60 – 70°C, depending on the product. Processing at temperatures conducive to the partial solidification of milk fat (i.e. 30 – 35°C) results in incomplete dispersion of the fat phase. Homogenization is most efficient when the fat phase is in a liquid state and in concentrations normal to milk.
7 - Question
Preferred Homogenization pressure is _______
a) 5- 15 MPa
b) 10-25 MPa
c) 25- 50 MPa
d) 60-70 MPa
View Answer
Explanation: Homogenization pressure is between 10 and 25 MPa (100 – 250 bar), depending on the product. High-pressure homogenisation procedures cause the formation of small fat globules.
8 - Question
The dispersion of the lipid phase increases with ________ temperatures of homogenisation and is commensurate with the_________ viscosity of milk at higher temperatures.
a) Increase, decrease
b) Increase, increase
c) Decrease, increase
d) Decrease, decrease
View Answer
Explanation: The dispersion of the lipid phase increases with increasing temperatures of homogenization and is commensurate with the decreasing viscosity of milk at higher temperatures.
9 - Question
Name the theory of homogenization According to which homogenization takes place when the liquid is leaving the gap, so the back pressure which is important to cavitation is important to homogenization.
a) Cavitation theory
b) Eddies theory
c) Current theory
d) Voltage theory
View Answer
Explanation: The cavitation theory, on the other hand, claims that the shock waves created when the steam bubbles implode disrupt the fat droplets. However, it is possible to homogenise without cavitation, but it is less efficient.
10 - Question
Which homogenization theory predicts how the homogenisinneffect varies with the homogenizing pressure?
a) Cavitation theory
b) Eddies theory
c) Current theory
d) Voltage theory
View Answer
Explanation: The theory of globule disruption by turbulent eddies is based on the fact that a lot of small eddies are created in a liquid travelling at a high velocity. Higher velocity gives smaller eddies. If an eddy hits an oil droplet of its own size, the droplet will break up. This theory predicts how the homogenizing effect varies with the homogenizing pressure.
11 - Question
Application of Single-stage homogenization is in?
a) Products demanding a high viscosity (certain cluster formation).
b) Product with low viscosity
c) Product with no viscosity
d) Product without fat
View Answer
Explanation: Single-stage homogenization may be used for homogenization of products demanding a high viscosity (certain cluster formation).
12 - Question
Two-stage homogenization may not be applied to which of the following?
a) Products with a high fat content
b) Products where high homogenization efficiency is desired.
c) Product with low viscosity
d) Product demanding high viscosity
View Answer
Explanation: Two-stage homogenization is used for products with a high fat content and products where high homogenization efficiency is desired.
13 - Question
Two-stage method is usually chosen to achieve optimal homogenization efficiency.
a) True
b) False
View Answer
Explanation: pressure is measured before the first stage, P1, and the homogenization pressure in the second stage is measured before the second stage, P2. The two-stage method is usually chosen to achieve optimal homogenization efficiency. Best results are obtained when the relation P1 / P2 is about 0.2.
14 - Question
The effect of homogenization on the physical structure of milk has which of the following advantages? I) Smaller fat globules leading to no cream-line formation II) Somewhat increased sensitivity to light – sunlight and fluorescent tubes III) Reduced heat stability
a) I) only
b) I) and III)
c) I), II) and III)
d) II) only
View Answer
Explanation: Homogenization has following advantages: Smaller fat globules leading to no cream-line formation, Whiter and more appetizing color, reduced sensitivity to fat oxidation, more full-bodied flavor, better mouth feel, and Better stability of cultured milk products.
15 - Question
Homogenization of milk may give milk which of the following off-flavor?
a) Fruity
b) Bitter
c) Sunlight
d) Salty
View Answer
Explanation: Homogenization has a disadvantage of increased sensitivity to light – sunlight and fluorescent tubes can result in Sunlight flavor to the milk.
16 - Question
Homogenization reduce the size of fat globules to which size?
a) Less than 2µ
b) Less than 3µ
c) Less than 4µ
d) Less than 5µ
View Answer
Explanation: Homogenization leads to a reduction of fat globule size to < 2 µ prevents formation of cream layer and increases the surface area of the fat above 6 times.
17 - Question
Which of the following is the effect of homogenization on the appearance of milk?
a) Dusty appearance
b) Yellowish appearance
c) Whitish appearance
d) Blackish appearance
View Answer
Explanation: Homogenization of milk increases its whitening power due to an increase in the number and surface area of the fat globules. Adsorption of casein micelles and serum proteins on newly created fat globules surface increases scattering of light thereby causing whiter appearance.
18 - Question
Homogenization has which of the following effects on the physiology of nutrition of milk?
a) Improved digestibility
b) Reduced digestibility
c) Cholesterol
d) Sugar
View Answer
Explanation: Homogenization has been reported to improve the digestibility of milk due to an increase in the number and surface area of the fat globules.
19 - Question
Which of the following does not denotes the flavor profile of homogenized milk?
a) Richer than unhomogenized milk
b) Smoother than unhomogenized milk
c) Creamier than unhomogenized milk
d) Bitter
View Answer
Explanation: Homogenized milk has a uniform flavor throughout. Homogenized milk tastes richer, smoother and creamier than unhomogenized milk due to an increase in the surface area of the fat globules which are uniformly distributed in milk.
20 - Question
Homogenized milk show sensitivity to which enzyme?
a) Lipases
b) Tryptases
c) Pepsin
d) Oxyin
View Answer
Explanation: Homogenized milk is more susceptible to enzyme activities, especially lipase action, than unhomogenized milk. Lipase can cause rancidity rapidly in homogenized raw milk.
21 - Question
Which of the following packaging material should be used in order to avoid off flavor formation in homogenized milk?
a) Transparent Glass bottles
b) Transparent bags
c) Opaque containers
d) Transparent containers
View Answer
Explanation: Homogenized milk is more susceptible to oxidized flavors caused by natural or artificial light than unhomogenized milk. To prevent the development of off-flavors, homogenized milk must be packaged in opaque containers, such as cartons, plastic containers or colored bottles.
22 - Question
Storage of homogenized milk may lead to which of the following development?
a) Sediment development
b) Fat development
c) Protein development
d) Cream layer development
View Answer
Explanation: Homogenized milk may develop dark sediment at the bottom of the container after standing for 24 h. Sedimentation in homogenized milk is due to the settling of cells, foreign matter and casein particles. In unhomogenized milk, these particles are usually held by the fat globules.
23 - Question
In order to prevent sedimentation in homogenized milk which of the following measure prove effective?
a) Heating
b) Pasteurization
c) Concentration of milk
d) Filtration/clarification of milk prior to homogenization
View Answer
Explanation: To prevent the sediment formation, homogenized milk must be filtered or clarified, preferably before homogenization.
24 - Question
The bacterial counts of milk will _______ after homogenization.
a) Increase
b) Decrease
c) Remain same
d) First increase then decrease
View Answer
Explanation: There will be an apparent increase in bacterial count after homogenization. Increase is due to the break-up of clumps and colonies of organisms.
25 - Question
The milk after homogenization will not be suitable for the production of semi-hard or hard cheeses due to which of the following reasons?
a) Too soft coagulum
b) Too hard coagulum
c) Off flavor
d) Bitter taste
View Answer
Explanation: The milk will not be suitable for the production of semi-hard or hard cheeses. This is because the coagulum will be too soft and difficult to dewater.
26 - Question
Homogenization in which the main body of skim milk is not homogenized, but only the cream together with a small proportion of skim milk is homogenized is called?
a) Complete homogenization
b) Partial homogenization
c) Concentrate homogenization
d) Pasteurized homogenization
View Answer
Explanation: Partial homogenization, this form of homogenization is mainly applied to pasteurized market milk. The basic reason is to reduce operating costs. Total power consumption is cut by some 65% because of the smaller volume passing through the homogenizer.
27 - Question
Main function of first stage of homogenization is?
a) Fat globule reduction
b) Separation of clusters of fat into individual fat molecules
c) Oxidation
d) Off flavor development
View Answer
Explanation: Most of the fat globule reduction takes place in the first stage. There is a tendency for clumping or clustering of the reduced fat globules after the first stage.
28 - Question
Main function of Second stage of homogenization is?
a) Fat globule reduction
b) Separation of clusters of fat into individual fat molecules
c) Oxidation
d) Off flavor development
View Answer
Explanation: There is a tendency for clumping or clustering of the reduced fat globules after the first stage. The second stage valve permits the separation of those clusters into individual fat globules.
29 - Question
Lack of homogenization leads to which of the following developments?
a) Cream layer development
b) Protein development
c) Astringency development
d) Increased fat content
View Answer
Explanation: Milk is an oil-in-water emulsion, with the fat globules dispersed in a continuous skim milk phase. In raw milk left to stand, the fat would rise and form a cream layer.
30 - Question
Which of the following factors does not contribute to enhanced stability of homogenized milk?
a) Decrease in the mean diameter of the fat globules
b) Decrease in the size distribution of the fat globules
c) Increase in density of the globules
d) Decrease in density of the globules
View Answer
Explanation: Three factors contribute to this enhanced stability of homogenized milk: a decrease in the mean diameter of the fat globules, a decrease in the size distribution of the fat globules, and an increase in density of the globules owing to the adsorption of a protein membrane.