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Correct choice is (a) 557.38 kg

The BEST explanation: THUS mixing of 3.05 kg of 6.5% fat milk with 3.40 kg of the SKIM milk will YIELD 6.45 kg of milk containing the DESIRED fat level i.e. 3.1%. Therefore, the quantity of skim milk required to be added to 500 kg whole milk will be (3.4 x 500)/3.05=3.05. Accordingly, 557.38 kg of 0.05% skim milk mixed with 500 kg of 6.5% fat whole milk will yield 1057.38 kg of milk having 3.1% fat.

The correct answer is (a) 725.4 kg

Explanation: Using Pearson’s Square method:

 PROPORTION of the WHOLE MILK = 2.46/3.86

Amount of whole milk required = (2.46/3.86)*2000 = 1274.6 kg

Proportion of SKIMMED milk = 1.4/3.86

Amount of skimmed milk required = (1.4/3.86)*2000 = 725.4 kg (or 2000 – 1274.6).

The correct answer is (a) More

Best EXPLANATION: The amount of bactofugate from the two-phase BACTOFUGE is about 3% of the feed, while the CORRESPONDING amount from the one-phase Bactofuge can be as low as 0.15% of the feed.

Correct OPTION is (C) Cheese processing

The explanation is: Bacteria belonging to the GENUS Clostridium – anaerobic spore-forming bacteria – are AMONG the most feared by cheese makers, as they can cause late blowing of cheese even if present in small NUMBERS. That is why cheese milk is bactofugated.

Right answer is (a) Decanter

Easy explanation: Bacteria, especially heat resistant spores, have a significantly higher density than the milk. A Bactofuge is THEREFORE a PARTICULARLY efficient MEANS of ridding milk of bacteria spores. Since these spores are also resistant to heat treatment, the Bactofuge makes a useful complement to thermisation, PASTEURIZATION and sterilization.

Correct answer is (a) Separate microorganisms from milk

The BEST I can explain: BACTOFUGATION is a BELGIAN process for removing BACTERIA from milk by high speed CENTRIFUGATION. It aims at separation of microorganisms from milk.

The correct option is (d) Fluctuation in protein CONTENT

Easiest explanation: For PRECISION in the PROCESS it is necessary to measure variable parameters such as fluctuations in the fat content of the incoming milk, fluctuations in THROUGHPUT, and fluctuations in preheating temperature. Most of the variables are interdependent; any deviation in one stage of the process often results in deviations in all stages.

The CORRECT OPTION is (c) Constant

The explanation is: The pressure in the skim milk outlet MUST be kept constant in order to enable accurate standardization. This pressure must be maintained regardless of variations in FLOW or pressure drop caused by the equipment after separation, and this is DONE with a constant-pressure valve located close to the skim milk outlet.

The CORRECT choice is (a) Pearson square method

Explanation: One of these methods, frequently used, is taken from the Dictionary of Dairying by J.G. Davis and is ILLUSTRATED by Pearson square method. How many kgs of cream of A% FAT must be mixed with skim milk of B% fat to make a mixture containing C% fat? The ANSWER is obtained from a square, where the given figures for fat contents are PLACED.

Right choice is (a) Adjustment of FAT content

For explanation I would SAY: STANDARDIZATION of fat content involves adjustment of the fat content of milk, or a milk product, by addition of cream or skim milk as appropriate to OBTAIN a given fat content.

The correct answer is (a) True

To explain: The flow velocity through the separation channels will be reduced if the flow rate through the MACHINE is reduced. Thus providing the fat globules more TIME to RISE and be discharged through the cream outlet. The skimming EFFICIENCY of a separator consequently increases with a decrease in THROUGHPUT and vice versa.

Right ANSWER is (a) GUSTAF de Laval

The explanation is: From 1890 the separators built by Gustaf de Laval were equipped with specially DESIGNED conical DISCS, the patent on which had been granted in 1888.

The correct CHOICE is (c) By keeping large PARTICLE in the center and smaller on the outside

For explanation I would say: The centrifuge WORKS USING the sedimentation principle, where the centripetal acceleration causes denser substances and PARTICLES to move outward in the radial direction. At the same time, objects that are less dense are displaced and move to the center.

Correct answer is (c) Centrifugation

To elaborate: A centrifuge is a machine with a RAPIDLY rotating container that applies centrifugal force to its CONTENTS, typically to SEPARATE fluids of different DENSITIES (e.g. cream from milk) or LIQUIDS from solids.

The correct answer is (c) FOULING

To explain I would say: Fouling is the accumulation of unwanted material on solid SURFACES to the detriment of function. DAIRY industry ALSO EXPERIENCES fouling problems by chemical reactions.

Right choice is (b) Regeneration efficiency

The best EXPLANATION: We can take the simplest OPERATING profile – heat treatment of raw MILK –as an example. Using this formula: where R = regenerative efficiency %, tr = milk TEMPERATURE after regeneration, ti = temperature of raw incoming milk, tp = PASTEURIZATION and temperature.

Right choice is (b) Convection

Easiest explanation: Convection CONSEQUENTLY involves mixing. When the teaspoon is RINSED with RUNNING cold water, heat GETS transferred from the SPOON to the water, which is heated in the process. The heated water when replaced by cold water, which in turn absorbs heat from the spoon. Heat transfer by convection continues until the spoon and the running water have the same temperature.

Right answer is (a) CONDUCTION

Best explanation: Conduction means a transfer of THERMAL energy through SOLID bodies and through layers of liquid at rest (without physical flow or mixing in the direction of heat transfer). The QUESTION shows an example of heat conduction to a TEASPOON in a cup of hot coffee. Heat is transferred by conduction to the handle, which becomes warmer.

The correct ANSWER is (d) 57°C to 68°C for 15 min

For explanation I would say: Thermization involves heating the milk to between 57°C to 68°C and hold for 15 minutes. Thermization targets pathogenic bacteria while LEAVING the good bacteria in the product. The low TEMPERATURES do not alter the structure and taste of the milk.

Correct choice is (a) 72°C to 74°C for 15 to 20 SECONDS

Easiest explanation: High temperature short TIME (HTST) PASTEURIZATION. HEAT the milk to between 72°C to 74°C for 15 to 20 seconds. Targets resistant PATHOGENIC bacterial spores (Clostridium botulinum spores).

Correct answer is (a) killing TUBERCLE bacillus

Explanation: The PASTEURIZATION of milk is a SPECIAL type of heat treatment which can be defined as “any heat treatment of milk which secures the certain DESTRUCTION of tubercle bacillus (T.B.) without markedly AFFECTING the physical and chemical properties”.

The correct answer is (B) Whey

To explain I would say: After centrifugation of MILK, the whey is left as the supernatant. A separator is a CENTRIFUGAL device which AIDS in separation of milk into cream and SKIMMED milk.

Right choice is (b) The more MASSIVE a biological particle is, the slower it moves in a centrifugal field

To explain: Sedimentation is the tendency for particles in suspension to SETTLE out of the fluid in which they are ENTRAINED, and come to rest against a barrier. The STATEMENT is false because the more massive a biological particle is, the faster it moves in a centrifugal field.

Right answer is (b) SEDIMENTATION rate, sizes and density

Best explanation: Differential CENTRIFUGATION is a process which is used to separate CERTAIN organelles from whole CELLS for further analysis of specific parts of cells. Differential centrifugation is a process based on the DIFFERENCES in the sedimentation rate of biological particles of different sizes and density.

Right option is (a) DECANTING

To ELABORATE: Decanting is a process to separate mixtures. Decanting is just allowing a MIXTURE of solid and liquid or two IMMISCIBLE liquids to settle and separate by GRAVITY. This process can be slow and tedious without the aid of a centrifuge.

Right choice is (c) centrifuging

Easy EXPLANATION: Decantation is a process for the separation of mixtures, by removing a LAYER of liquid, generally one from which a precipitate has settled. CENTRIFUGATION helps in the removal of fine INSOLUBLE particles in a SOLUTION.

Correct OPTION is (c) centrifuging

For explanation I WOULD SAY: A suspension is a heterogeneous mixture containing solid PARTICLES that are sufficiently large for sedimentation. Liquids containing suspension can be purified USING centrifugation.

Correct option is (C) settles at bottom

For explanation: These PARTICLES can sediment at the bottom of the tube into what’s known as a PELLET, and this isolated specimen, or the remaining solution, the supernatant, can be further processed or analyzed.

Correct option is (a) 1890

To explain: The PLATE heat EXCHANGER was PATENTED in 1890 by the German inventors Langen and Hundhausen.

The correct answer is (a) Simple

The BEST EXPLANATION: Thanks to the vertical DESIGN, the product can be displaced by water with minimum intermixing which helps assure product RECOVERY at the end of every run. Following this, completely drainage facilitates CIP and product CHANGEOVER.

Correct choice is (a) Plate heat exchanger

Best EXPLANATION: Most heat treatment of dairy products is carried out in plate heat EXCHANGERS. The plate heat exchanger (often abbreviated PHE) CONSISTS of a pack of STAINLESS steel plates CLAMPED in a frame.

The correct OPTION is (d) Multi/mono CHANNEL and Multi/mono TUBE

The explanation is: TUBULAR heat exchangers (THE) are in some cases used for pasteurization/ UHT treatment of dairy products. Tubular heat exchangers are available in two FUNDAMENTALLY different types; multi/mono channel and multi/mono tube.

Correct answer is (c) Holding for a long holding time

The explanation: Correct heat treatment requires that the milk is held for a specified time at PASTEURIZATION temperature. This is DONE in an external holding CELL. A holding cell usually consists of a pipe arranged in a spiral or zigzag pattern and often covered by a metal shroud to PREVENT people from being burned if they touch the holding cell.

Correct choice is (c) Regeneration

Easy explanation: Regeneration (Heating): The RAW COLD incoming milk is PARTIALLY and INDIRECTLY HEATED by the hot outgoing milk (milk-to-milk regeneration). This adds to the economy.

Correct option is (d) Thickness of stainless steel

The explanation is: The RATE of BUILDUP of fouling depends on many factors such as temperature difference between product and heating MEDIUM, Milk QUALITY, Air content of the product and PRESSURE conditions in the heating section.

Right option is (a) Larger

The explanation is: A liquid with high viscosity DEVELOPS less turbulence when it flows through the HEAT exchanger COMPARED to a PRODUCT with lower viscosity. This means a larger heat exchanger is needed, everything else being constant.

Correct OPTION is (C) Overall heat transfer coefficient

For explanation I would say: The overall heat transfer coefficient refers to how well heat is conducted over a SERIES of MEDIUMS. This FACTOR, k, is a measure of how efficient the heat transfer is.

Right answer is (c) Corrugated

The EXPLANATION: The partition is OFTEN corrugated to create a more turbulent FLOW, which results in BETTER HEAT transfer. The thickness is also important. The thinner the partition, the better the heat transfers.

Right answer is (a) Countercurrent

Explanation: The cold product then MEETS the cold HEATING medium at the inlet and a progressively WARMER medium as it passes through the heat exchanger. During the PASSAGE, the product is gradually heated so that the temperature is always only a few degrees below that of the heating medium at the CORRESPONDING point. This type of arrangement is called a countercurrent flow.

The correct option is (a) Double

Explanation: In the QUESTION the SIZE needs to be doubled as The flow RATE, V, is determined by the planned CAPACITY of the dairy. The higher the flow rate, the larger the HEAT exchanger needed.