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 papersHow the arrangement of molecules and phases decides texture, stability and digestion: emulsions, foams, gels and their stability, structure-function design, encapsulation and delivery of bioactives, digestion models, and the science and regulation of nanoscale food materials.
In the exams: ICAR AIEEA-PG Code 18 Unit I (colloidal systems, gels and emulsions); ICAR AICE 35.b Unit 5 (emulsions, foams, gels; hydrocolloids)
How our questions for ICAR AIEEA-PG / PGS spread across the units of Food Structure, Colloids, Encapsulation & Nanotechnology. Difficulty: 19 easy, 19 medium, 0 hard.
| Protein and polysaccharide gels | 8 | |
| Foams and aerated foods | 6 | |
| Microencapsulation: spray drying, coacervation and extrusion | 6 | |
| Colloidal systems in foods: dispersions, emulsions, foams and gels | 4 | |
| Emulsion formation and stability mechanisms | 4 | |
| Structure-function relationships and food structure design | 4 | |
| Interfacial science: surfactants and proteins at interfaces | 3 | |
| Protein-polysaccharide interactions | 2 | |
| In-vitro digestion models and bioaccessibility | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Which equipment produces submicron droplets in milk and infant formula?
A. High-pressure valve homogeniser
High-pressure homogenisers generate turbulence and cavitation in a narrow gap; mixers and mills do not.
Further reading: McClements, Food Emulsions; Dickinson, An Introduction to Food Colloids
What is disproportionation in foams?
D. Gas diffusing from small bubbles to larger ones
Higher Laplace pressure in small bubbles drives gas through the liquid to larger ones.
Further reading: McClements, Food Emulsions; Dickinson, An Introduction to Food Colloids
Which food is a solid foam?
C. Bread
Bread crumb is a set gluten-starch matrix with gas cells.
Further reading: McClements, Food Emulsions; Dickinson, An Introduction to Food Colloids
What conditions does high-methoxyl pectin need to gel?
A. High sugar and low pH
HM pectin needs soluble solids above about 55% and pH about 2.8–3.5; LM pectin gels with calcium.
Further reading: Phillips and Williams, Handbook of Hydrocolloids; Walstra, Physical Chemistry of Foods
How do calcium ions gel alginate?
C. By bridging guluronic blocks in egg-box junctions
Ca²⁺ cross-links G-blocks of adjacent chains; LM pectin gels the same way.
Further reading: Phillips and Williams, Handbook of Hydrocolloids; Walstra, Physical Chemistry of Foods
Why is high-methoxyl pectin added to drinking yoghurt at pH about 4?
C. It coats casein and stops aggregation
Adsorbed pectin gives negative charge and steric repulsion to casein near its pI.
Further reading: Phillips and Williams, Handbook of Hydrocolloids; Walstra, Physical Chemistry of Foods
A spray-dried fish oil powder has 30 g total oil and 1.5 g surface oil per 100 g. What is the encapsulation efficiency?
B. 95%
EE = (30 − 1.5)/30 × 100 = 95%. 5% is the surface fraction; 28.5% is the encapsulated mass in g; 105% adds the values.
Further reading: Zuidam and Nedović, Encapsulation Technologies; McClements, Food Emulsions
Why are volatile flavours retained during spray drying better than their volatility suggests?
C. Water escapes faster than flavour through the dry skin
Once a skin forms, larger flavour molecules diffuse much more slowly than water.
Further reading: Zuidam and Nedović, Encapsulation Technologies; McClements, Food Emulsions
How are alginate beads for probiotics usually formed?
D. Dripping alginate into calcium chloride
Calcium cross-links alginate instantly, forming gel beads.
Further reading: Zuidam and Nedović, Encapsulation Technologies; McClements, Food Emulsions
Which wall material forms inclusion complexes holding small flavour molecules in a cavity?
B. β-Cyclodextrin
Cyclodextrins have hydrophobic cavities that host small non-polar molecules.
Further reading: Zuidam and Nedović, Encapsulation Technologies; McClements, Food Emulsions
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