Agricultural/Bioengineering Agricultural/Bioengineering: Dairy Engineering 2

Question 1

What is the primary purpose of homogenization in fluid milk processing?

Accepted Answer

To reduce fat globule size and prevent cream separation

Answer

To pasteurize milk by applying pressure

Answer

To increase protein content through mechanical shearing

Answer

To remove bacterial spores by high-pressure filtration

Question 2

In a plate heat exchanger used for milk pasteurization, what does the regeneration section accomplish?

Accepted Answer

It pre-heats incoming cold raw milk using hot outgoing pasteurized milk

Answer

It heats raw milk using steam from a boiler

Answer

It cools pasteurized milk using chilled water

Answer

It sterilizes the plates between batches using caustic solution

Question 3

A dairy plant measures the brix value of whey concentrate at 60°. What is this measurement primarily indicating?

Accepted Answer

Total dissolved solids expressed as equivalent sucrose percentage

Answer

Fat percentage by weight

Answer

Protein content determined by refractometry

Answer

Lactose crystallization onset temperature

Question 4

What does the term 'somatic cell count' (SCC) in raw milk primarily indicate?

Accepted Answer

The level of udder inflammation and mastitis presence in the herd

Answer

The number of lactic acid bacteria per mL

Answer

The concentration of casein micelles per mL

Answer

The degree of fat globule clustering measured by microscopy

Question 5

Which membrane separation process is most appropriate for concentrating casein micelles while passing lactose and whey proteins through?

Accepted Answer

Microfiltration (MF)

Answer

Reverse osmosis (RO)

Answer

Nanofiltration (NF)

Answer

Electrodialysis

Question 6

In cheese manufacturing, what is the role of calcium chloride (CaCl₂) addition to pasteurized milk?

Accepted Answer

It restores calcium ions lost during pasteurization to improve rennet coagulation

Answer

It lowers pH to accelerate acid coagulation

Answer

It acts as a preservative against spoilage bacteria

Answer

It increases the fat content to meet legal standards

Question 7

A spray dryer producing whole milk powder operates with an inlet air temperature of 180°C and an outlet of 80°C. What is the primary reason outlet temperature is kept below 100°C?

Accepted Answer

To prevent Maillard browning and heat damage to lactose and proteins

Answer

To reduce energy costs by limiting steam consumption

Answer

To maintain positive pressure inside the drying chamber

Answer

To ensure the powder is at equilibrium moisture content above 8%