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 papersDesigning and validating heat processes that make food safe and shelf-stable: microbial death kinetics, heat penetration, process calculation by the general and formula methods, retorts and aseptic systems, and the regulatory framework for low-acid canned foods. Agricultural Engineering's food-dairy-engineering introduces D, z and F; this subject teaches the full process-establishment practice.
In the exams: GATE XE-G Section 3 (thermal processing) and Section 4 (thermal sterilisation); ICAR AIEEA-PG Code 18 Unit II (thermobacteriology, sterilisation); ICAR AICE 35.a Unit 2 (process time evaluation for canned products)
ICAR AIEEA-PG / PGS — Code 18 Food Science Technology
Unit II names thermobacteriology, pasteurisation and sterilisation; Unit III names canning, packaging and containers. Questions are MCQs at definition and short-calculation level: 12D and F0, commercial sterility, acid classes, types of spoilage (flat sour, TA, sulphide), double-seam parts and faults, retort types and aseptic processing.
How our questions for ICAR AIEEA-PG / PGS spread across the units of Thermal Processing & Canning Technology. Difficulty: 22 easy, 23 medium, 1 hard.
| Acid and low-acid foods; pH 4.6 and the target organism | 7 | |
| Can making, double seams and seam evaluation | 6 | |
| Lethality, F0 and the 12D concept | 5 | |
| Commercial sterility and spoilage probability | 5 | |
| Retort types: still, rotary, hydrostatic and continuous | 5 | |
| Thermal death kinetics: D value, z value and the thermal death time curve | 3 | |
| Heat penetration tests and cold-spot determination | 3 | |
| Pasteurisation of acid and acidified foods | 3 | |
| Retort pouches and flexible containers | 2 | |
| Aseptic processing and packaging | 2 | |
| Quality optimisation: cook value and nutrient retention | 2 | |
| Regulatory control of low-acid canned foods and process authorities | 2 | |
| Process calculation: the general method | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Swollen cans from one production lot yield a mixed flora of cocci, short rods and some spore-formers. The most likely cause is
A. post-process leakage through seams
Cocci and other non-spore-formers cannot survive a retort process, so their presence points to contamination after processing, usually through faulty seams. Underprocessing typically leaves a pure culture of spore-formers; thermophilic spoilage gives thermophilic spore-formers; pre-process spoilage shows growth without viable organisms. Leakage typically happens during cooling.
Further reading: US FDA Bacteriological Analytical Manual
A can with both ends bulged that can be pushed in by thumb pressure but return when released is described as a
C. soft swell
A soft swell has both ends bulged but yielding to pressure. A flipper looks normal until struck; a springer has one end bulged that can be pushed in, making the other bulge; a hard swell cannot be pushed in at all.
Further reading: Fellows, Food Processing Technology
Swollen cans of an acid fruit contain hydrogen gas and no viable microorganisms. The most likely cause is
B. acid corrosion of the tinplate
Hydrogen swell results from acid attacking the metal; it is chemical, not microbial. C. botulinum does not grow in acid fruit; air entry does not produce hydrogen; flat-sour organisms produce acid without gas. The corroding tinplate releases the hydrogen.
Further reading: Fellows, Food Processing Technology
Venting a steam retort at the start of the cycle is essential because
D. air left in the retort creates cooler zones where cans are underprocessed
A steam-air mixture is cooler than pure steam at the same pressure, and air pockets insulate containers, so air must be vented. Steam is the heating medium; venting does not raise pressure; bleeders and drains handle condensate.
Further reading: Fellows, Food Processing Technology
The inner layer of a typical retortable pouch, which forms the heat seal, is usually made of
B. polypropylene
Cast polypropylene is used as the sealant because it seals well and withstands retort temperatures. Polyester is the outer strength and print layer; aluminium foil is the barrier layer; nylon is sometimes added for puncture resistance, not sealing.
Further reading: Holdsworth and Simpson, Thermal Processing of Packaged Foods
The aluminium foil layer in a retort pouch laminate mainly provides
A. a barrier to oxygen, light and moisture
Foil gives an almost complete barrier to gases, light and moisture, which gives long shelf life. Sealing is by the polypropylene inner layer; printing is usually on or under the polyester outer layer.
Further reading: Holdsworth and Simpson, Thermal Processing of Packaged Foods
In aseptic processing and packaging,
C. food and package are sterilised separately and combined in a sterile zone
Aseptic systems sterilise the product by rapid heating and the package by chemical or thermal means, then fill and seal in sterile conditions. In-container retorting is conventional canning.
Further reading: Fellows, Food Processing Technology
The cook value C is usually expressed with
D. reference 100 °C and z = 33 °C
The cook value uses a quality z (commonly 33 °C) at 100 °C. 121.1 °C with z = 10 °C defines F₀; the others are not standard cook-value conventions.
Further reading: Holdsworth and Simpson, Thermal Processing of Packaged Foods
A process authority, in low-acid canning regulation, is
B. an expert person or body in thermal processing who establishes the scheduled processes
Process authorities have the expertise and facilities to design heat penetration and distribution studies and set scheduled processes. Inspectors, controllers and retailers have other roles.
Further reading: US FDA, 21 CFR Parts 108, 113 and 114
The international Codex text that sets hygiene requirements for low-acid canned foods is the
D. Code of Hygienic Practice for Low-Acid and Acidified Low-Acid Canned Foods
The Code of Hygienic Practice for Low-Acid and Acidified Low-Acid Canned Foods covers scheduled processes, retort operation, containers and records. The other Codex texts cover labelling, aflatoxin and additives.
Further reading: Codex Code of Hygienic Practice for Low-Acid and Acidified Low-Acid Canned Foods
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