Engineering Questions with Answers - Multiple Choice Questions

Primary Production of Milk Engineering MCQs

1 - Question

Pore size Micro-filtration membrane ranges from _________
a) 0.1- 5µm
b) 0.1- 0.01µm
c) 0.001- 0.01µm
d) 0.0001- 0.001µm
View Answer Answer: a
Explanation: The pore size on microfiltration membranes ranges from 0.1 – 5 um, and has the largest pore size of the four main membrane types. Its pores are large enough to filter out such things as bacteria, blood cells, flour, talc and many other kinds of fine dust in solution. This can be contributed to its pores which are relatively large compared to other membranes; it can be operated under low pressures and therefore low energy.



2 - Question

Pore size Ultra-filtration membrane ranges from ________
a) 0.1- 5µm
b) 0.1- 0.01µm
c) 0.001- 0.01µm
d) 0.0001- 0.001µm
View Answer Answer: b
Explanation: Ultra filtration has a pore size range of 0.1um to 0.01um. UF membranes reject particles such as silica, viruses, endotoxins, proteins, plastics and smog/fumes such as ZnO. Due to the decrease in pore size, the osmotic pressure required is higher than that of MF.



3 - Question

Pore size Nano-filtration membrane ranges from __________
a) 0.1- 5µm
b) 0.1- 0.01µm
c) 0.001- 0.01µm
d) 0.0001- 0.001µm
View Answer Answer: c
Explanation: Nanofiltration has a pore size range of 0.001-0.01um. NF membranes can filter particles up to and including some salts, synthetic dies and sugars, however it is unable to remove most aqueous salts and metallic ions, as such, NF is generally confined to specialist uses.



4 - Question

Pore size RO membrane ranges from _____________
a) 0.1- 5µm
b) 0.1- 0.01µm
c) 0.001- 0.01µm
d) 0.0001- 0.001µm
View Answer Answer: d
Explanation: Reverse Osmosis has a pore size range of 0.0001 – 0.001. It is by far the finest separation material available to industry. It is used on a large scale for the desalination and purification of water as it filters out everything but water molecules, with pore sizes approaching the radius of some atoms in many cases.



5 - Question

The solution to be concentrated or fractionated is called?
a) Feed
b) Flux
c) Membrane fouling
d) Permeate
View Answer Answer: a
Explanation: Inlet solution which has to be fractionated is called feed. Once feed is injected the membrane filtration process starts.



6 - Question

The term for deposition of solids on the membrane, irreversible during processing is?
a) Feed
b) Flux
c) Membrane fouling
d) Permeate
View Answer Answer: c
Explanation: Membrane fouling is a process whereby a solution or a particle is deposited on a membrane surface or in membrane pores in a process such as in a Membrane bioreactor so that the membrane’s performance is degraded. It is a major obstacle to the widespread use of this technology.



7 - Question

The concentrate, the retained liquid is called ___________
a) Permeate
b) Retentate
c) Concentration factor
d) Diafilteration
View Answer Answer: b
Explanation: Retentate is the matter that is retained by a semi permeable membrane during dialysis; non-dialyzable matter; a substance of this kind.



8 - Question

What is the volume reduction achieved by concentration, i.e. the ratio of the initial volume of feed to the final volume of concentrate called?
a) Permeate
b) Retentate
c) Concentration factor
d) Diafilteration
View Answer Answer: c
Explanation: The concentration factor is the degree that the RO feed water dissolved solids is concentrated in the brine. Concentration Factor = 1/ (1- Y).



9 - Question

_________ is a modification of ultra filtration in which water is added to the feed as filtration proceeds in order to wash out feed components which will pass through the membranes, basically lactose and minerals.
a) Permeate
b) Retentate
c) Concentration factor
d) Diafiltration
View Answer Answer: d
Explanation: Diafiltration is a technique that uses ultra filtration membranes to completely remove, replace, or lower the concentration of salts or solvents from solutions containing proteins, peptides, nucleic acids, and other biomolecules.



10 - Question

Which of the following membrane separation technique would be most suitable for dehydration of whey in dairy industry?
a) Reverse osmosis
b) Nano filtration
c) Ultra filtration
d) Membrane filtration
View Answer Answer: a
Explanation: Reverse osmosis in dairy industry is used for dehydration of whey, UF permeate and condensate.



11 - Question

Which of the following membrane separation technique would be most suitable for partial desalination of whey in dairy industry?
a) Reverse osmosis
b) Nano filtration
c) Ultra filtration
d) Membrane filtration
View Answer Answer: b
Explanation: Nano filtration in dairy industry used when partial desalination of whey, UF permeates or retentate is required.



12 - Question

Which of the following membrane separation technique would be most suitable for the concentration of milk proteins in dairy industry?
a) Reverse osmosis
b) Nano filtration
c) Ultra filtration
d) Membrane filtration
View Answer Answer: c
Explanation: UF in dairy industry is typically used for concentration of milk proteins in milk and whey and for protein standardization of milk intended for cheese, yoghurt and some other products.



13 - Question

Which of the following membrane separation technique would be most suitable for the reduction of bacteria in skim milk?
a) Reverse osmosis
b) Nano filtration
c) Ultra filtration
d) Membrane filtration
View Answer Answer: d
Explanation: MF in dairy industry is basically used for reduction of bacteria in skim milk, whey and brine, but also for defatting whey intended for whey protein concentrate (WPC) and for protein fractionation.



14 - Question

What is the Processing temperature in membrane filtration applications?
a) 15℃
b) 25℃
c) 65℃
d) 50℃
View Answer Answer: d
Explanation: In most cases, the processing temperature is about 50°C for dairy applications. Filtration plants are normally supplemented with a simple cooling system integrated into the internal circulation loop to compensate for the slight rise in temperature that occurs during operation and maintain a constant processing temperature.



15 - Question

The separation limit for a membrane is determined by the lowest ___________ that can be separated.
a) Fractional weight
b) Molecular weight
c) Ion weight
d) Mass
View Answer Answer: b
Explanation: Membranes with a definite separation limit separate everything with a definitely lower molecular weight, while membranes with a diffuse limit let some material with a higher molecular weight through and stop some with a lower molecular weight.



16 - Question

Statement related to the process of evaporation that is incorrect is?
a) Evaporation occurs at any temperature
b) Evaporation takes place within liquid
c) Temperature may change during evaporation
d) No bubbles are formed in liquid during evaporation
View Answer Answer: b
Explanation: Some of the salient features of evaporation are it occurs at any temperature, It might lead to temperature change. It has been noted that no bubbles are formed in liquid during evaporation.



17 - Question

Rate of evaporation is______
a) directly proportional to temperature of liquid
b) inversely proportional to temperature of liquid
c) independent of temperature of liquid
d) directly proportional to humidity of surrounding air
View Answer Answer: a
Explanation: Evaporation depends directly on temperature of liquid. Higher the temperature of the substance the greater is the kinetic energy of the molecules at its surface and therefore the faster the rate of their evaporation.



18 - Question

Rate of evaporation increases as?
a) exposed surface area of liquid increases
b) exposed surface area of liquid decreases
c) movement of air above surface of liquid decreases
d) atmospheric pressure increases
View Answer Answer: b
Explanation: A substance that has a larger surface area will evaporate faster, as there are more surface molecules per unit of volume that are potentially able to escape.



19 - Question

Rate of evaporation decreases as?
a) temperature increases
b) humidity of surrounding air increases
c) movement of air above surface of liquid increases
d) atmospheric pressure decreases
View Answer Answer: b
Explanation: Humidity is the amount of water vapor present in the air. The air around us cannot hold more than a definite amount of water vapor at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases.



20 - Question

Which of the following factors do not affect the rate of evaporation?
a) Temperature of liquid
b) Humidity of surrounding air
c) Depth of liquid
d) Surface of liquid
View Answer Answer: c
Explanation: The rate of condensation increases if the temperature of the gas is decreased. On the other hand, the rate of evaporation increases if the temperature of the liquid is increased. It is also increased if: the surface area of the liquid is increased.



21 - Question

Evaporation occurs only _____
a) after boiling
b) after extreme cooling
c) at surface of a liquid
d) if boiling occurs at atmospheric pressure
View Answer Answer: c
Explanation: Evaporation takes place at a surface and below the boiling point. The surface atoms or molecules gains energy from surroundings and overcome the attractions of other molecules & get to vaporize.



22 - Question

Compounds evaporating easily and giving off a smell are?
a) ionic compounds
b) covalent bonds
c) metallic bonds
d) dative bonds
View Answer Answer: b
Explanation: ‘Hospital smells’ are really covalent compounds floating in the air and these attacks our noses. This means that molecules can escape from the liquid fairly easily and evaporate.



23 - Question

When heating begins in miscible solutions, vapors formed will be?
a) of liquid lower in boiling point
b) of liquid higher in boiling point
c) vapors will be of both liquids with a higher concentration of liquid having low boiling point
d) collected in a gas syringe
View Answer Answer: c
Explanation: Vapors will be of both liquids with a higher concentration of liquid having low boiling point as the heating starts in miscible solution.



24 - Question

Evaporation of solution of CuSO4 helps in?
a) making it concentrated
b) crystallization of CuSO4
c) evaporation of salt CuSO4
d) concentration and crystallization
View Answer Answer: d
Explanation: The solution turns blue because of diffusion. On heating the solution nothing will happen. Evaporation of solution of CuSO4 leads to its concentration and crystal formation.



25 - Question

Crystallization, evaporation and distillation are a means of?
a) separating soluble substances in solution
b) separating insoluble substances in solutions
c) separating filtrate from solution
d) concentration
View Answer Answer: a
Explanation: Crystallization, evaporation and distillation are methods of separation of soluble substances in a solution.



26 - Question

Concentration is different than drying.
a) True
b) False
View Answer Answer: a
Explanation: Concentration of a liquid means removal of a solvent, in most cases water; concentration is distinguished from drying in that the final product – the concentrate – is still liquid.



27 - Question

Which of the following is not the reason for the concentration of food liquids?
a) reduce the cost of drying
b) induce crystallization
c) reduce costs for storage and transportation
d) increase water activity in order to increase microbiological and chemical
View Answer Answer: d
Explanation: There are several reasons for concentrating food liquids, e.g. to reduce the cost of drying, induce crystallization, reduce costs for storage and transportation, reduce water activity in order to increase microbiological and chemical stability and to recover by-products from waste streams.



28 - Question

Evaporation in dairy industry is a preliminary step to which of the following process?
a) Drying
b) Flavoring
c) Watering
d) Pasteurization
View Answer Answer: a
Explanation: Dairy industry evaporation is used for concentration duties such as milk, skim milk and whey. It is also used as a preliminary step to drying. Milk products intended for milk powder are normally concentrated from an initial solids content of 9 – 13% to a final concentration of 40 – 50% total solids before the product is pumped to the dryer.



29 - Question

Evaporation in dairy industry is done under __________
a) Vacuum
b) Heater
c) Dryer
d) Pasteurizer
View Answer Answer: a
Explanation: The products to be evaporated are normally heat sensitive and can be destroyed by adding heat. To reduce this heat impact, evaporation takes place under vacuum, sometimes at temperatures as low as 40°C.



30 - Question

Which evaporators can be used when a low degree of concentration is required?
a) Falling film evaporator
b) Circular type evaporator
c) Tubular type evaporator
d) Plate type evaporator
View Answer Answer: b
Explanation: Circulation evaporators can be used when a low degree of concentration is required or when small quantities of product are processed. In yogurt production, for example, evaporation is utilized to concentrate milk 1.1 to 1.25 times, or from 13% to 14.5% or 16.25% solids content respectively. This treatment simultaneously de-aerates the product and rids it of off-flavors.

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