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 papers
10worked here, free
120written to this exam in this subject
14syllabus units
What this subject covers
The minor constituents that decide colour, flavour and nutritional value, the enzymes that act in raw and processed food, and the browning reactions — enzymatic and non-enzymatic — that every food technologist must control or exploit.
In the exams: GATE XE-G and XL-U Section 1 (pigments, flavours, enzymes, browning); ICAR AIEEA-PG Code 18 Unit I (food flavours); ICAR AICE 35.a Unit 7 (flavour chemistry technology)
Pigments: chlorophylls, carotenoids, anthocyanins, betalains, tannins and myoglobin
Colour changes during processing and storage
Flavour chemistry: terpenes, esters, aldehydes, ketones and sulphur compounds
Taste: sweet, sour, salty, bitter and umami compounds
Flavour generation during processing, fermentation and maturation
Vitamins: stability during processing and storage
Minerals in foods and their chemistry
Food enzymes: specificity, kinetics, inhibition and coenzymes
Endogenous enzymes in raw materials: lipoxygenase, polyphenol oxidase, peroxidase and pectinases
Industrial enzymes in food processing
Enzymatic browning and its control
Maillard reaction and caramelisation
Acrylamide and other process contaminants from browning
Phenolic compounds and natural antioxidants
Where the 120 questions fall
How our questions for GATE spread across the units of Food Chemistry II: Pigments, Flavours, Vitamins, Minerals, Enzymes & Browning. Difficulty: 36 easy, 77 medium, 7 hard.
Food enzymes: specificity, kinetics, inhibition and coenzymes
11
Pigments: chlorophylls, carotenoids, anthocyanins, betalains, tannins and myoglobin
10
Flavour chemistry: terpenes, esters, aldehydes, ketones and sulphur compounds
10
Vitamins: stability during processing and storage
10
Colour changes during processing and storage
9
Taste: sweet, sour, salty, bitter and umami compounds
9
Minerals in foods and their chemistry
9
Flavour generation during processing, fermentation and maturation
8
Industrial enzymes in food processing
8
Maillard reaction and caramelisation
8
Phenolic compounds and natural antioxidants
8
Enzymatic browning and its control
7
Acrylamide and other process contaminants from browning
7
Endogenous enzymes in raw materials: lipoxygenase, polyphenol oxidase, peroxidase and pectinases
6
10 practice questions, worked
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
5 · Endogenous enzymes in raw materials: lipoxygenase, polyphenol oxidase, peroxidase and pectinases · medium
Why is a little soy flour added to wheat flour in some breads?
Its lipoxygenase bleaches carotenoids, whitening the crumb
Its pectinases soften the crust
Its polyphenol oxidase darkens the crumb
Its trypsin inhibitors slow staling
Answer and working
A. Its lipoxygenase bleaches carotenoids, whitening the crumb
Coupled oxidation by lipoxygenase bleaches flour carotenoids and also aids dough mixing tolerance.
Further reading: Handbook of Food Enzymology
6 · Industrial enzymes in food processing · medium
What is the main advantage of immobilised enzymes?
Higher activity than any free enzyme in every case
No effect of temperature on activity
No need for any pH control in the reactor
The enzyme is reused and the process runs continuously
Answer and working
D. The enzyme is reused and the process runs continuously
Enzymes bound to supports in columns can be used repeatedly; activity may be lower than free enzyme.
Further reading: Handbook of Food Enzymology
7 · Maillard reaction and caramelisation · medium
How does pH affect the rate of the Maillard reaction?
It is not affected by pH at all
It is fastest at pH 1 and stops above pH 5
It is faster at higher pH, where amino groups are unprotonated
It occurs only at exactly neutral pH
Answer and working
C. It is faster at higher pH, where amino groups are unprotonated
The unprotonated amino group is the reactive form, so alkaline conditions speed browning, as in pretzels dipped in lye.
Further reading: Belitz, Grosch and Schieberle, Food Chemistry
8 · Maillard reaction and caramelisation · medium
Caramelisation differs from the Maillard reaction because it:
Requires polyphenol oxidase and oxygen to proceed
Produces mainly sulphur compounds
Occurs only at refrigeration temperatures
Involves sugars heated without amino compounds
Answer and working
D. Involves sugars heated without amino compounds
Caramelisation is thermal degradation of sugars, catalysed by acid or base, at higher temperatures.
Further reading: Belitz, Grosch and Schieberle, Food Chemistry
9 · Acrylamide and other process contaminants from browning · medium
How does IARC classify acrylamide?
Group 1, carcinogenic to humans with sufficient evidence
Group 2A, probably carcinogenic
Not evaluated by IARC
Group 3, not classifiable at all
Answer and working
B. Group 2A, probably carcinogenic
IARC placed acrylamide in Group 2A in 1994.
Further reading: IARC Monographs Volume 60
10 · Phenolic compounds and natural antioxidants · easy
Which flavonoid subclass includes hesperidin and naringin of citrus?
Flavan-3-ols
Isoflavones
Flavanones
Anthocyanidins
Answer and working
C. Flavanones
Isoflavones are soy compounds; flavan-3-ols are catechins.
Further reading: Fennema's Food Chemistry
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