ICAR AIEEA-PG / PGS — Code 18 Food Science Technology · India · ICAR through the National Testing Agency
Original practice questions written to the published syllabus · not past papersLow-temperature preservation from the food's side: chilling and controlled atmospheres, freezing-point depression and ice crystallisation, freezing-time calculation, freezer types, frozen storage changes and thawing. The refrigeration cycle and cold-store design are in Agricultural Engineering's refrigeration-cold-chain.
In the exams: GATE XE-G Section 3 (chilling, freezing) and Section 4 (freezing and crystallisation); ICAR AICE 35.a Unit 2 (IQF products)
ICAR AIEEA-PG / PGS — Code 18 Food Science Technology
Unit II lists freezing among unit operations and refrigeration among utilities; Unit IV lists preservation by cold. MCQs test types of freezers, cryogens and their temperatures, blanching indicators, freezer burn, thaw rigor, glazing, IQF and the −18 °C standard.
How our questions for ICAR AIEEA-PG / PGS spread across the units of Chilling, Freezing & Frozen Food Technology. Difficulty: 15 easy, 27 medium, 2 hard.
| Chilling and chilled storage of foods | 7 | |
| Changes during frozen storage: freezer burn, drip loss and oxidation | 6 | |
| Freezing-point depression and unfrozen water | 5 | |
| Air-blast, plate, cryogenic and IQF freezers | 5 | |
| Freezing of fruits, vegetables, meat, fish and ready meals | 5 | |
| Cold-chain requirements for chilled foods | 4 | |
| Ice nucleation, crystal growth and recrystallisation | 4 | |
| Thawing and tempering | 4 | |
| Time-temperature tolerance and shelf life of frozen foods | 2 | |
| Freezing-time prediction: Plank's equation and its refinements | 1 | |
| Supercooling, isochoric and other emerging freezing methods | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Bananas stored at 5 °C develop dark skin and fail to ripen. This is
A. chilling injury
Tropical fruits suffer chilling injury below a critical temperature, about 10–13 °C for bananas, though no ice forms. Freezer burn and cold shortening concern frozen foods and meat.
Further reading: Fellows, Food Processing Technology
Most foods begin to freeze at a temperature slightly below 0 °C because
D. dissolved solutes depress the freezing point
Sugars, salts and acids lower the freezing point; typical initial freezing points are about −0.5 to −3 °C.
Further reading: Singh and Heldman, Introduction to Food Engineering
Frozen foods conduct heat better than unfrozen foods mainly because
B. ice conducts heat about four times better than liquid water
Thermal conductivity of ice (about 2.2 W/m K) is roughly four times that of water (about 0.6), so the frozen layer transfers heat well.
Further reading: Singh and Heldman, Introduction to Food Engineering
In Plank's equation, the shape factors for an infinite slab are
D. P = 1/2 and R = 1/8
Slab 1/2 and 1/8; cylinder 1/4 and 1/16; sphere 1/6 and 1/24.
Further reading: Singh and Heldman, Introduction to Food Engineering
Horizontal plate freezers are best suited to
D. flat retail packs of uniform thickness
Plates must contact both flat faces; irregular items and loose particles need blast, IQF or other freezers.
Further reading: Fellows, Food Processing Technology
Vegetables are blanched before freezing mainly to
C. inactivate enzymes
Blanching inactivates enzymes that would cause off-flavours, discoloration and nutrient loss in frozen storage; it reduces but does not eliminate microbes.
Further reading: Fellows, Food Processing Technology
Ice crystals found inside packages of frozen vegetables usually indicate
D. temperature fluctuations during storage
Warming and cooling drive moisture from the product to the pack's colder surfaces, where it refreezes as frost.
Further reading: Kennedy (ed.), Managing Frozen Foods
Codex texts and many national laws define quick-frozen foods as foods held at the thermal centre at
A. −18 °C or colder
−18 °C after thermal stabilisation is the common reference, with brief limited rises permitted in distribution.
Further reading: Kennedy (ed.), Managing Frozen Foods
Microwave thawing is often uneven because
A. liquid water absorbs microwaves much more strongly than ice
Thawed spots heat rapidly while neighbouring ice stays cold — runaway heating; pulsed defrost settings reduce it.
Further reading: Singh and Heldman, Introduction to Food Engineering
Dehydrofreezing of fruits and vegetables involves
B. partial drying before freezing
Removing part of the water first reduces freezing load and drip and gives a denser product.
Further reading: Sun (ed.), Handbook of Frozen Food Processing and Packaging
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