ICAR AICE-JRF/SRF (PhD) — Food Processing Technology, Food Safety & Quality, Processing and Food Engineering · India · ICAR through the National Testing Agency
Original practice questions written to the published syllabus · not past papersMeasuring and modelling how foods flow, deform, break and transfer heat: rheometry of fluids and gels, viscoelasticity, texture profile analysis, and thermal, electrical and optical properties. Agricultural Engineering's engineering-properties-biomaterials covers size, shape, density and friction of grains and produce; this subject goes deeper into processed foods and their measurement.
In the exams: ICAR AIEEA-PG Code 18 Units I–II (physical properties of foods; engineering properties of food materials); ICAR AICE 37 Unit 5 (rheology of dairy foods)
ICAR AICE-JRF/SRF (PhD) — Food Processing Technology, Food Safety & Quality, Processing and Food Engineering
37 Unit 5 is rheology of dairy foods, and 35.b Unit 5 covers emulsions, foams and gels; 41 Unit 1 covers engineering properties of biomaterials. Expect deeper questions on viscoelastic models, oscillatory parameters and gel points, cheese meltability and stretch, glass transition by DSC and DMA, and state diagrams.
How our questions for ICAR AICE-JRF/SRF spread across the units of Physical Properties, Rheology & Texture of Foods. Difficulty: 8 easy, 53 medium, 21 hard.
| Viscoelasticity: creep, stress relaxation and oscillatory rheology | 11 | |
| Texture: texture profile analysis and empirical texture tests | 10 | |
| Physical properties of foods: density, porosity and particle size distribution | 9 | |
| Colour measurement: CIE L*a*b* and colour difference | 9 | |
| Electrical and dielectric properties of foods | 7 | |
| Glass transition and state diagrams | 7 | |
| Time-dependent flow: thixotropy and rheopexy | 6 | |
| Rheology of doughs and dairy gels | 6 | |
| Newtonian and non-Newtonian fluids: power-law, Herschel-Bulkley and Casson models | 5 | |
| Rotational and capillary viscometry | 5 | |
| Thermal properties: specific heat, thermal conductivity and diffusivity of foods | 4 | |
| Fundamentals of rheology: stress, strain and viscosity | 3 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Porosity strongly lowers the thermal conductivity of a dry food mainly because
D. air in the pores conducts heat very poorly
Air (about 0.025 W/m K) is a good insulator, so porous foods conduct poorly.
Further reading: Sahin and Sumnu, Physical Properties of Foods
The volume mean diameter d43 compared with the Sauter mean d32 for a broad distribution is
B. larger, because it weights large particles more
d43 = Σnd⁴/Σnd³ gives more weight to large particles than d32 = Σnd³/Σnd².
Further reading: Sahin and Sumnu, Physical Properties of Foods
The yield stress of a sauce is best measured without wall-slip errors using
B. a vane geometry rotated slowly
The vane shears within the sample, avoiding slip at smooth walls and disturbing the structure little.
Further reading: Steffe, Rheological Methods in Food Process Engineering
A laboratory reports viscosity of an oil without stating temperature. The main problem is that
C. viscosity varies strongly with temperature
Viscosity of liquids is strongly temperature-dependent; methods specify temperature and its control.
Further reading: Steffe, Rheological Methods in Food Process Engineering
In a stress relaxation test on a Maxwell material (λ = 10 s), the initial stress is 100 Pa. After 20 s the stress is about
B. 13.5 Pa
σ = 100 e^(−20/10) = 100 e^(−2) = 13.5 Pa. 36.8 Pa is after one relaxation time (10 s); 50.0 Pa assumes linear decay.
Further reading: Rao, Rheology of Fluid, Semisolid, and Solid Foods
The Maxwell model consists of
D. a spring and dashpot in series
Series spring–dashpot (Maxwell) represents a viscoelastic liquid; parallel (Kelvin–Voigt) a viscoelastic solid.
Further reading: Rao, Rheology of Fluid, Semisolid, and Solid Foods
The extensograph measures
B. resistance and extensibility of rested dough
Dough is stretched to rupture after resting; the curve gives resistance, extensibility and energy.
Further reading: Bourne, Food Texture and Viscosity
A pizza-cheese supplier must show its cheese melts and stretches well. Suitable tests are
C. a Schreiber melt test and a strand-stretch test
Meltability is measured by spread on heating (Schreiber, Arnott); stretch by pulling strands from melted cheese.
Further reading: Rao, Rheology of Fluid, Semisolid, and Solid Foods
The illuminant D65 used in colour measurement represents
A. average daylight
D65 approximates daylight (about 6,500 K); illuminant A represents incandescent light.
Further reading: Sahin and Sumnu, Physical Properties of Foods
Glass transition temperatures from DSC should be reported with
D. onset or midpoint, heating rate and method
Tg occurs over a range and depends on heating rate and technique.
Further reading: Roos, Phase Transitions in Foods
Ten here, 82 in the app. The Laisha app has every practice question we have written to ICAR AICE-JRF/SRF in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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