GATE — Life Sciences (XL), Section U Food Technology · India · IITs and IISc on rotation (2026: IIT Guwahati)
Original practice questions written to the published syllabus · not past papersFrom oilseed to finished fat: mechanical expression and solvent extraction, refining, bleaching and deodorisation, fat modification by hydrogenation, interesterification and fractionation, and the fat products — margarine, shortening, vanaspati and specialty fats — made from them.
In the exams: GATE XE-G Section 3 (oil processing: expelling, solvent extraction, refining, hydrogenation); ICAR AICE 35.a Unit 2 (oilseed processing, vanaspati)
GATE — Engineering Sciences (XE), Section G Food Technology
Section 3 names oil processing: expelling, solvent extraction, refining and hydrogenation. Expect MCQs on refining steps and their purposes, hydrogenation and trans formation, and NATs on oil recovery from mass balance, NaOH for neutralisation, FFA from acid value and mean molecular weight from saponification value.
GATE — Life Sciences (XL), Section U Food Technology
Same Section 3 content, with chemistry of fats: iodine and saponification values, polymorphism, interesterification and oxidation.
How our questions for GATE spread across the units of Fats & Oils Technology. Difficulty: 14 easy, 8 medium, 2 hard.
| Neutralisation, bleaching and deodorisation; physical refining | 3 | |
| Oil quality tests: acid value, peroxide value, iodine value and saponification value | 3 | |
| Sources and composition of edible oils and fats | 2 | |
| Mechanical expression and expellers | 2 | |
| Solvent extraction and desolventising | 2 | |
| Hydrogenation and trans fatty acids | 2 | |
| Interesterification: chemical and enzymatic | 2 | |
| Fractionation | 2 | |
| Margarine, shortening and vanaspati | 2 | |
| Degumming and lecithin recovery | 1 | |
| Specialty fats and cocoa butter equivalents | 1 | |
| Frying oil deterioration and management | 1 | |
| By-products of oil refining | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
The pungency of kachi ghani mustard oil comes from:
B. Allyl isothiocyanate
Glucosinolates are hydrolysed by myrosinase.
Further reading: Chakraverty, Post Harvest Technology; Bailey's
In alkali refining, free fatty acids are removed as:
B. Soapstock
Sodium hydroxide converts them to soaps.
Further reading: Shahidi (ed.), Bailey's Industrial Oil and Fat Products
The catalyst most used for edible oil hydrogenation is:
D. Nickel
Sodium methoxide is for interesterification.
Further reading: Shahidi (ed.), Bailey's Industrial Oil and Fat Products
Under the Codex fat spreads standard, margarine contains at least:
D. 80% fat
Reduced-fat spreads contain less.
Further reading: Shahidi (ed.), Bailey's Industrial Oil and Fat Products
An oil has an acid value of 2.0. What is its FFA content as oleic acid?
C. 1.0%
FFA = acid value / 1.99 = 2.0/1.99 = 1.0%.
Further reading: AOCS Official Methods; FSSAI manual of methods for oils and fats
An oil has a saponification value of 190. What is its approximate mean triacylglycerol molecular weight?
B. 886
3 × 56,100/190 = 886. 295 omits the factor of 3.
Further reading: AOCS Official Methods; FSSAI manual of methods for oils and fats
FSSAI requires frying oil to be discarded when total polar compounds exceed:
B. 25%
Many countries use about 24–27%.
Further reading: Bailey's; FSSAI frying oil guidance
Acid oil is produced by acidulating:
C. Soapstock
Sulphuric acid splits the soaps.
Further reading: Shahidi (ed.), Bailey's Industrial Oil and Fat Products
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