GATE — Engineering Sciences (XE), Section G Food Technology · India · IITs and IISc on rotation (2026: IIT Guwahati)
Original practice questions written to the published syllabus · not past papersThe four constituents that make up most of any food and how they behave during processing and storage: water and its mobility, sugars and starch, proteins and their functional properties, and lipids and their oxidation.
In the exams: GATE XE-G and XL-U Section 1 (carbohydrates, proteins, lipids); ICAR AIEEA-PG Code 18 Unit I; ICAR AICE 35.b Unit 5 (emulsions, foams, gels, functional properties)
GATE — Engineering Sciences (XE), Section G Food Technology
Section 1 names starch, cellulose, pectic substances and dietary fibre, gelatinisation and retrogradation; protein classification and structure, post-mortem changes and tenderisation; lipid classification and structure, rancidity, polymerisation and polymorphism; and changes during processing. Expect one-mark recall and reasoning items (which starch fraction causes staling, which polymorph is smooth, why PSE forms) and short numericals on water activity, fat constants and protein from nitrogen.
GATE — Life Sciences (XL), Section U Food Technology
Same Section 1 content as XE-G. Life-science candidates also meet amino acid chemistry, isoelectric points and enzyme-related reasoning through the compulsory chemistry section; questions often connect structure to function (disulphide bonds in gluten, β-1,4 versus α-1,4 linkages).
How our questions for GATE spread across the units of Food Chemistry I: Water, Carbohydrates, Proteins & Lipids. Difficulty: 25 easy, 45 medium, 20 hard.
| Water in foods: structure, bound and free water, sorption isotherms and water activity | 9 | |
| Amino acids, peptides and protein structure | 9 | |
| Monosaccharides, disaccharides and oligosaccharides | 7 | |
| Starch: structure, gelatinisation, pasting and retrogradation | 7 | |
| Post-mortem changes and tenderisation of muscle proteins | 7 | |
| Cellulose, pectic substances, gums and dietary fibre | 6 | |
| Food proteins: classification and sources | 6 | |
| Protein denaturation and functional properties: solubility, gelation, emulsification and foaming | 6 | |
| Lipids: classification, structure and nomenclature | 6 | |
| Lipid oxidation: autoxidation, photo-oxidation, rancidity and antioxidants | 6 | |
| Hydrolytic rancidity and thermal polymerisation of frying oils | 6 | |
| Chemical and physical changes in macronutrients during processing | 6 | |
| Physical properties of fats: crystallisation and polymorphism | 5 | |
| Glass transition and molecular mobility | 4 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Which group of microorganisms can grow at the lowest water activity?
B. xerophilic moulds and osmophilic yeasts, down to about aw 0.61
Xerophilic moulds and osmophilic yeasts are the most tolerant, growing to about 0.61. Most spoilage bacteria need above about 0.90; Salmonella needs about 0.93 or more; lactic acid bacteria are not the low-aw limit.
Further reading: Damodaran and Parkin, Fennema's Food Chemistry
Loss of birefringence (the Maltese cross) when starch granules are heated in water indicates
C. gelatinisation
Gelatinisation melts crystalline order, so birefringence disappears. Retrogradation is re-association on cooling; dextrinisation is dry-heat breakdown; syneresis is weeping of liquid from a gel.
Further reading: Belitz, Grosch and Schieberle, Food Chemistry
Pectin with a degree of esterification of 35 % is classified as
D. low-methoxyl pectin
The dividing line is 50 % esterification; 35 % is low-methoxyl. Protopectin is the insoluble parent form in unripe fruit.
Further reading: Belitz, Grosch and Schieberle, Food Chemistry
Oat and barley β-glucans are associated with lowering blood cholesterol mainly because they
B. form viscous solutions in the gut that slow absorption and bind bile acids
Mixed-linkage β-glucans are soluble and viscous, reducing bile-acid reabsorption and cholesterol uptake. They are not digested to glucose and are not insoluble bulking fibres.
Further reading: Belitz, Grosch and Schieberle, Food Chemistry
The covalent cross-link between two cysteine residues that is important in gluten and in egg-white gels is a
C. disulphide bond
Oxidation of two cysteine thiol groups forms an S–S disulphide bond. Peptide bonds join the backbone; hydrogen bonds are non-covalent; glycosidic bonds join sugars.
Further reading: Belitz, Grosch and Schieberle, Food Chemistry
In the Osborne classification, proteins soluble in about 70 % aqueous ethanol are called
A. prolamins
Prolamins (gliadin, zein, hordein) dissolve in aqueous alcohol. Albumins dissolve in water, globulins in dilute salt, glutelins in dilute acid or alkali.
Further reading: Belitz, Grosch and Schieberle, Food Chemistry
Egg white fails to whip into a stable foam in a bowl containing traces of fat because
A. lipids compete for the air–water interface and disrupt the protein film
Lipids and egg yolk adsorb at the interface and break the cohesive protein film, so bubbles coalesce. The other explanations are incorrect.
Further reading: Damodaran and Parkin, Fennema's Food Chemistry
In autoxidation of lipids, the propagation step is
D. ROO• + RH → ROOH + R•
Propagation transfers the radical: a peroxyl radical takes hydrogen from another lipid, forming a hydroperoxide and a new alkyl radical. The first equation is initiation, the third termination, the fourth hydroperoxide decomposition.
Further reading: Frankel, Lipid Oxidation
Acrylamide forms in fried and baked foods mainly from
B. asparagine and reducing sugars at high temperature and low moisture
Acrylamide is a Maillard-related product of free asparagine with reducing sugars above about 120 °C in dry conditions. Boiling, freezing and refrigeration do not form it.
Further reading: Damodaran and Parkin, Fennema's Food Chemistry
Caramelisation differs from the Maillard reaction in that caramelisation
A. involves sugars alone heated to high temperature, without amino compounds
Caramelisation is the thermal degradation of sugars by themselves; the Maillard reaction needs amino groups and can proceed at lower temperatures.
Further reading: Damodaran and Parkin, Fennema's Food Chemistry
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