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 papersMaking sugar from cane and beet, non-centrifugal sugars such as jaggery, alternative sweeteners, and the sugar and chocolate confectionery built on them.
In the exams: ICAR AIEEA-PG Code 18 Unit III (sugars and sweets); GATE XE-G Section 3 (cocoa); ICAR AICE 35.a Unit 2 (confectionery products)
GATE — Engineering Sciences (XE), Section G Food Technology
Section 3 names cocoa among plantation products, and Section 4 brings evaporation and crystallisation. Expect conceptual items on chocolate refining, conching and tempering (cocoa butter form V), bloom, and numerical-answer mass balances: juice evaporation to syrup, jaggery yield, invert sugar mass, HFS blending and recipe fat content.
GATE — Life Sciences (XL), Section U Food Technology
Same Section 3 content as XE-G. Science graduates meet sugar chemistry framed through optical rotation (inversion), reducing sugars and DE, glucose isomerase, polyols and Maillard browning in toffee and chocolate flavour.
How our questions for GATE spread across the units of Sugar, Sweeteners, Chocolate & Confectionery Technology. Difficulty: 6 easy, 32 medium, 9 hard.
| Chocolate manufacture: refining, conching and tempering | 7 | |
| Glucose syrups, invert sugar and high-fructose syrups | 6 | |
| Sugar alcohols and high-intensity sweeteners | 6 | |
| Cane sugar manufacture: extraction, clarification, evaporation and crystallisation | 5 | |
| Sugar confectionery: hard-boiled sweets, toffee, fondant and gums | 5 | |
| Sugarcane and sugar beet as raw materials | 4 | |
| Fat bloom and sugar bloom | 4 | |
| Confectionery quality and shelf life | 4 | |
| Refining and specialty sugars | 3 | |
| Sugar by-products: molasses, bagasse and press mud | 2 | |
| Jaggery and other non-centrifugal sugars | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A cane juice reads 18.0 °Brix and 15.3 pol. Its purity is
C. 85.0
Purity = 15.3 ÷ 18.0 × 100 = 85.0. 117.6 inverts the ratio; 2.7 is Brix minus pol; 82.5 has no consistent basis.
Further reading: Chen and Chou, Cane Sugar Handbook
Seed crystals are introduced into the vacuum pan when the syrup is in the
D. Metastable zone
In the metastable zone existing crystals grow but new nuclei do not form spontaneously, so seeding there gives a controlled number of crystals. In the labile zone false grain forms; undersaturated syrup dissolves seed; a glass transition is unrelated to pan boiling.
Further reading: Hugot, Handbook of Cane Sugar Engineering
In enzymic manufacture of glucose syrup, the enzyme used for liquefaction of gelatinised starch is
B. Thermostable α-amylase
A heat-stable α-amylase thins the gelatinised starch to dextrins at high temperature. Glucoamylase saccharifies the dextrins to glucose, glucose isomerase makes fructose, and invertase splits sucrose.
Further reading: BeMiller and Whistler, Starch: Chemistry and Technology
100 kg of sucrose is completely inverted. The mass of invert sugar formed is about
D. 105.3 kg
Sucrose (342.3) + water (18.0) → glucose + fructose (360.3), so 100 × 360.3 ÷ 342.3 = 105.3 kg. 100 kg ignores the water taken up; 95 kg divides the wrong way; 52.6 kg counts only one of the two monosaccharides.
Further reading: BeMiller and Whistler, Starch: Chemistry and Technology
Xylitol and erythritol give a cooling sensation in the mouth because they
C. Have a strongly negative heat of solution
Both polyols absorb heat as they dissolve, cooling the mouth, which suits mint confectionery and gum. They contain no terpenes, need no frozen storage and release no gas.
Further reading: Nabors (ed.), Alternative Sweeteners
Which sweetener is least suitable for a baked product that is heated for a long time?
B. Aspartame
Aspartame breaks down with heat, especially at neutral pH, and loses sweetness. Sucralose and acesulfame potassium are heat-stable, and sorbitol is a stable polyol.
Further reading: Nabors (ed.), Alternative Sweeteners
Chocolate whose largest particles are well above about 30 µm is likely to taste
D. Gritty
The tongue detects particles above roughly 20–30 µm as grittiness, so refining targets a maximum size near that range. Bitterness, waxiness and sourness depend on flavour and fat, not particle size.
Further reading: Beckett (ed.), Industrial Chocolate Manufacture and Use
Compound coatings made with lauric fats such as palm kernel fat are used partly because they
C. Need no tempering
Lauric fats crystallise directly in a stable form, so coatings made with them do not need tempering. They contain little or no cocoa butter, melt near mouth temperature, and can develop soapy off-flavours if lipase acts on them.
Further reading: Beckett (ed.), Industrial Chocolate Manufacture and Use
A customer returns chocolate with a white film. A drop of water placed on the film dissolves it. The defect is
B. Sugar bloom
Sugar crystals dissolve in water, so a film that disappears under a drop of water is sugar bloom. Fat bloom does not dissolve in water, mould shows growth, and untempered chocolate shows streaks and softness.
Further reading: Beckett, The Science of Chocolate
Water activity of a confection mainly determines
B. Microbial growth and moisture migration
Water activity controls which microorganisms can grow and whether the product gains or loses moisture to its surroundings and neighbouring components. Sweetness, melting and colour depend on other factors.
Further reading: Hartel, von Elbe and Hofberger, Confectionery Science and Technology
Ten here, 47 in the app. The Laisha app has every practice question we have written to GATE 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.
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