ASRB NET — Farm Machinery & Power / Land & Water Management Engineering / Agricultural Structures & Process Engineering · India · Agricultural Scientists Recruitment Board (ICAR)
Original practice questions written to the published syllabus · not past papersMoisture, drying, parboiling, milling, cleaning, size reduction and conveying of grains, pulses and oilseeds.
In the exams: GATE AG Section 6 (~14 marks a year 2019–26; psychrometry in all 8 papers, rice milling in 6 of 8); ICAR AIEEA-PG Unit VI; ICAR AICE subject 41; NCEES PE processing; PRC ABE bioprocess; ASRB NET ASPE
ASRB NET — Agricultural Structures & Process Engineering
Post-harvest operations, engineering properties, process equipment design and material handling at PG level, with emphasis on Indian practice: LSU and recirculating dryers, hot-soak parboiling, rubber-roll and disc huskers, dhal milling pretreatments, expellers and solvent plants.
How our questions for ASRB NET spread across the units of Post-Harvest Engineering of Cereals, Pulses & Oilseeds. Difficulty: 17 easy, 29 medium, 8 hard.
| Seed processing | 8 | |
| Equilibrium moisture content and sorption isotherms | 6 | |
| Pulse milling | 6 | |
| Oil expression and solvent extraction | 6 | |
| Grain dryers: bin, LSU, recirculating, fluidised-bed and solar | 5 | |
| Paddy and rice milling: husking, whitening, polishing and yields | 5 | |
| Parboiling and hydrothermal treatment | 4 | |
| Cleaning, grading and screening effectiveness | 4 | |
| Drying theory: constant and falling rate periods | 3 | |
| Wheat milling | 3 | |
| Moisture content: wet and dry basis | 2 | |
| Conveying: belt, bucket, screw and pneumatic | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
How much water must be added to 500 kg of wheat at 11% wet-basis moisture to temper it to 16% wet basis?
D. 29.8 kg
Dry matter = 500 × 0.89 = 445 kg. Final mass = 445/0.84 = 529.76 kg, so water to add = 29.8 kg. 25 kg (5% of 500) ignores that the total mass grows as water is added; 28.1 kg divides by the initial rather than the final (1 − M). 22.3 kg multiplies the dry matter by the 5-point rise (445 × 0.05).
Further reading: Sahay and Singh, Unit Operations of Agricultural Processing
A capacitance-type grain moisture meter works mainly because
B. water has a much higher dielectric constant than dry grain matter
Capacitance meters measure the dielectric constant (permittivity) of the sample; water's permittivity is far higher than that of dry matter. Conduction is the principle of resistance meters, and NIR absorption is a different instrument.
Further reading: Chakraverty, Post Harvest Technology of Cereals, Pulses and Oilseeds
A tray holds 50 kg of dry solid on 2 m² and dries at a constant rate R_c = 1.5 kg/m²·h down to the critical moisture X_c = 0.6 (db); the rate then falls linearly to zero at X_e = 0.05. The falling-rate time from 0.6 to 0.15 kg/kg (db) is closest to
A. 15.6 h
t_f = [W_s(X_c − X_e)/(A R_c)] ln[(X_c − X_e)/(X − X_e)] = (50 × 0.55/3) × ln(0.55/0.10) = 9.167 × 1.7047 = 15.63 h. Dropping the log term gives 9.2 h; using total rather than free moisture in the log gives 12.7 h; 25.6 h is the total including the constant-rate period.
Further reading: Earle, Unit Operations in Food Processing
The LSU dryer is best described as a
B. continuous mixed-flow column dryer with alternate rows of inverted-V inlet and outlet ducts
Grain flows down by gravity past rows of inverted-V channels connected alternately to the hot-air plenum and the exhaust, and a fluted discharge roll sets the flow rate.
Further reading: Chakraverty, Post Harvest Technology of Cereals, Pulses and Oilseeds
Wheat is conditioned (tempered) with water before milling chiefly to
D. toughen the bran and mellow the endosperm so they separate cleanly
Toughened bran stays in large flakes and mellowed endosperm reduces easily with less energy. Conditioning does not gelatinise starch; that is parboiling.
Further reading: Posner and Hibbs, Wheat Flour Milling
Dhal milling of pulses consists essentially of
D. dehulling the seed and splitting it into cotyledons
Dhal is the dehulled, usually split, cotyledon; flour and oil are different products.
Further reading: Chakraverty, Post Harvest Technology of Cereals, Pulses and Oilseeds
Commercial dhal recovery falls short of the theoretical yield mainly because
D. abrasion removes cotyledon as powder and produces brokens along with the husk
Abrasive dehullers cannot remove husk without also removing some cotyledon, and splitting creates brokens. Moisture change during pretreatment is balanced out when yields are corrected to the same moisture.
Further reading: Chakraverty, Post Harvest Technology of Cereals, Pulses and Oilseeds
In solvent extraction of oilseeds, 'miscella' is
A. the solution of oil in solvent leaving the extractor
Miscella is distilled to separate oil from solvent, which is condensed and reused. The meal goes to the desolventiser-toaster.
Further reading: Bailey's Industrial Oil and Fat Products
To remove chaff and dust from grain with an aspirator, the air velocity should be set
B. above the terminal velocity of light impurities but below that of the grain
Only particles whose terminal velocity is below the air velocity are lifted. Too high a velocity carries grain away; too low leaves the chaff.
Further reading: Sahay and Singh, Unit Operations of Agricultural Processing
By Harrington's rules of thumb, lowering seed moisture by 2 percentage points and storage temperature by 10 °C would multiply expected storage life by roughly
A. 16
Moisture: 2 × 2 = 4; temperature: each 5 °C fall doubles life, so 10 °C gives 4; combined 4 × 4 = 16. Adding the factors (4 + 4 = 8) is the common slip. 6 adds the moisture factor to a single temperature doubling (4 + 2).
Further reading: Harrington's rules for seed storage
Ten here, 54 in the app. The Laisha app has every practice question we have written to ASRB NET 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.
Free for ten days, then one subscription of US$10 a month. We would rather say so here than have you find it later.
An AI operating system for agriculture: free guides, manuals and tools written for every country.