Agricultural/Bioengineering Agricultural/Bioengineering: Food Engineering 4

Question 1

In centrifugal separation of cream from milk, the separation efficiency depends primarily on:

Accepted Answer

Temperature and density difference between fat and skim milk

Answer

Stokes' law governs centrifugal separation; efficiency increases with temperature (reduces viscosity) and with the density difference between the fat globules and the continuous skim milk phase.

Question 2

Ohmic heating of food products works by passing electric current through the food, which:

Accepted Answer

Generates heat uniformly throughout the volume due to electrical resistance

Answer

Ohmic heating converts electrical energy to heat throughout the food volume as current flows through it, enabling rapid and relatively uniform internal heating.

Question 3

The 'retrogradation' of starch during bread staling results from:

Accepted Answer

Recrystallization of amylopectin chains during storage

Answer

Retrogradation occurs as gelatinized amylopectin chains realign and form crystalline structures during storage, increasing stiffness and perceived staleness.

Question 4

In ultrafiltration (UF) membrane processing of whey, the retentate is enriched in:

Accepted Answer

Whey proteins

Answer

UF membranes (typical MWCO 10–100 kDa) retain large whey protein molecules in the retentate while lactose, minerals, and water pass through as permeate.

Question 5

Which food additive functions as a chelating agent to improve the efficacy of antimicrobials and retard lipid oxidation?

Accepted Answer

EDTA (ethylenediaminetetraacetic acid)

Answer

EDTA chelates pro-oxidant metal ions like iron and copper, slowing lipid oxidation and destabilizing gram-negative bacterial outer membranes to enhance antimicrobial effectiveness.

Agricultural/Bioengineering Practice Test

Agricultural/Bioengineering Practice Test

Agricultural/Bioengineering Agricultural/Bioengineering: Food Engineering 4