ICAR AICE-JRF/SRF Emerging & Non-thermal Dairy Processing: practice questions

1 · High pressure processing · easy

What pressure range is most used commercially in high pressure processing?

1. 4–6 MPa
2. 400–600 MPa
3. 40–60 kPa
4. 4,000–6,000 MPa

2 · High pressure processing · easy

Which microorganisms are most resistant to high pressure alone at ambient temperature?

1. Bacterial spores
2. Moulds
3. Yeasts
4. Gram-negative rods

3 · Pulsed electric fields · medium

What is the mechanism of microbial inactivation by pulsed electric fields?

1. Dissolving cell walls with ozone
2. Heating the cell interior to over 100 °C
3. Electroporation of the cell membrane
4. Breaking covalent bonds in DNA directly

4 · Ultrasound in processing and cleaning · easy

What frequency range is typical of power ultrasound for processing?

1. About 2–10 GHz
2. About 2–10 MHz
3. About 20–100 kHz
4. About 20–100 Hz

5 · Ultrasound in processing and cleaning · easy

What is the main mechanism by which power ultrasound acts in liquids?

1. Joule heating
2. Acoustic cavitation
3. Electroporation
4. Ionising radiation

6 · Supercritical fluid extraction · medium

Why is ethanol added as a co-solvent when extracting phospholipids?

1. Ethanol sterilises the extraction vessel
2. Supercritical CO2 is non-polar and dissolves them poorly
3. Phospholipids react with CO2 to form gas
4. Ethanol lowers the critical pressure of CO2 to zero

7 · Microencapsulation and nanotechnology · hard

How do regulators usually treat deliberately engineered nanomaterials in food?

1. They treat them exactly as bulk materials
2. They ban all nanostructures, including casein micelles
3. They exempt them from any assessment
4. They require specific safety assessment

8 · Regulatory approval of novel processes · medium

Under a pressure treatment, the target organism's D value is 0.8 min. What minimum holding time gives a 6-log reduction?

1. 7.5 min
2. 4.8 min
3. 0.13 min
4. 6.8 min

9 · Regulatory approval of novel processes · medium

In EU novel food law, when is a food from a new process 'novel'?

1. Only when the food is imported
2. When the process significantly changes composition
3. Whenever the factory or production line is newly built
4. Whenever the process uses electricity at any stage

10 · Regulatory approval of novel processes · medium

Why can't pressure-treated milk simply be called 'pasteurised milk' in many jurisdictions?

1. Pressure treatment is banned for all foods everywhere
2. Pasteurisation is defined by thermal processes
3. Pasteurised milk must be sold frozen
4. Pressure-treated milk contains no protein