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 papersEvery major beverage: water treatment and carbonated soft drinks, tea, coffee and cocoa processing, and the brewing, winemaking and distilling of alcoholic drinks, with their quality control.
In the exams: GATE XE-G Section 2 (alcoholic beverages, vinegar) and Section 3 (tea, coffee, cocoa); ICAR AIEEA-PG Code 18 Unit III (alcoholic and non-alcoholic beverages)
GATE — Engineering Sciences (XE), Section G Food Technology
Section 2 names alcoholic beverages and vinegar; Section 3 names tea, coffee and cocoa among plantation crops. Expect process-sequence and definition questions (withering, CTC, cut test, mashing, malolactic fermentation, distillation cuts) and numerical-answer items on alcohol from sugar by the Gay-Lussac equation, acetic acid from ethanol, moisture balances in tea and cocoa, and Brix or dilution balances.
GATE — Life Sciences (XL), Section U Food Technology
Same syllabus as XE-G. Science graduates meet the microbiology side more often: yeast species for ale and lager, the microbial succession in cocoa fermentation, acetic acid bacteria in vinegar, lactic acid bacteria in malolactic fermentation and spoilage organisms in juices and beer.
How our questions for GATE spread across the units of Beverage Technology: Soft Drinks, Tea, Coffee, Cocoa & Alcoholic Beverages. Difficulty: 26 easy, 54 medium, 23 hard.
| Wine making: red, white and fortified wines | 11 | |
| Coffee processing: wet and dry methods, roasting and instant coffee | 9 | |
| Malting and brewing: mashing, boiling, fermentation and maturation | 9 | |
| Distilled spirits: distillation and maturation | 9 | |
| Fruit wines, cider and traditional fermented beverages | 9 | |
| Water for beverages: treatment and quality | 8 | |
| Carbonated soft drinks: formulation, carbonation and filling | 8 | |
| Functional, sports and energy drinks | 8 | |
| Tea processing: black, green and oolong; instant tea | 8 | |
| Cocoa processing: fermentation, drying and roasting | 8 | |
| Beverage packaging and stability | 8 | |
| Quality control and legal standards for beverages | 8 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Why is alkalinity (mainly bicarbonate) removed from water used for acidic soft drinks?
B. It neutralises the added acid so the drink tastes flat and pH rises
Bicarbonate neutralises part of the citric or phosphoric acid, so the drink tastes flat and its pH rises, weakening the preservative hurdle. Softness does not limit CO2 solubility, sucrose does not precipitate with bicarbonate, and chlorine taste comes from residual disinfectant.
A plant keeps a free chlorine residual of 0.5 mg/L for 30 minutes of contact before carbon filtration. Its CT value is
A. 15 mg·min/L
CT = residual concentration × contact time = 0.5 × 30 = 15 mg·min/L. 60 divides 30 by 0.5; 0.017 divides 0.5 by 30; 30.5 adds the numbers.
Why do many sports drinks combine glucose (or maltodextrin) with fructose rather than use glucose alone?
B. The two sugars use separate intestinal transporters, so more is absorbed
Glucose is absorbed by the sodium-dependent SGLT1 transporter and fructose by GLUT5, so mixtures increase the total carbohydrate that can be absorbed. Fructose is carrier-transported, glucose does not caramelise at normal pasteurisation, and freezing point is irrelevant.
The orange-red pigments in black tea liquor associated with brightness and briskness are
C. Theaflavins
Theaflavins, formed by oxidative coupling of catechins, give brightness and briskness; thearubigins give colour and body. Anthocyanins are grape and berry pigments, carotenoids are not the liquor colour, and chlorophylls are green.
Freeze-dried instant coffee is generally preferred to spray-dried for premium products because
B. Low-temperature drying retains more volatile aroma
Freeze-drying sublimes ice at low temperature, so more volatile aroma is kept; it is more costly in energy. Both methods give low moisture; extraction yield is set in the extraction battery, not the dryer.
Fermented cocoa beans are dried for safe storage to a moisture content of about
A. 7–8%
About 7–8% moisture prevents mould growth in storage. 20–25% would mould, 12–14% is still too wet for cocoa, and 1–2% is unnecessarily low and makes beans brittle.
Fermenting 200 g/L of hexose completely by the Gay-Lussac equation releases carbon dioxide of about
A. 98 g/L
CO2 yield = 2 × 44.01/180.16 = 0.489 g per g sugar; 200 × 0.489 = 97.7, about 98 g/L. 102 is the ethanol; 200 assumes all mass becomes gas; 49 counts only one mole of CO2.
During malolactic fermentation, 3 g/L of malic acid (134.09 g/mol) is fully converted. The lactic acid formed (90.08 g/mol) is about
D. 2.0 g/L
Malic → lactic + CO2 is 1:1 by mole: 3 × 90.08/134.09 = 2.02 g/L lactic acid, with about 0.98 g/L CO2. 3.0 assumes mass is conserved; 1.0 is the CO2; 4.5 inverts the molar mass ratio.
In sake brewing, 'multiple parallel fermentation' means that
C. Koji mould saccharifies starch while yeast ferments alongside
Aspergillus oryzae (koji) enzymes convert rice starch to sugar at the same time as yeast ferments it, in one vessel. It is not sequential tanks, bottle refermentation or a bacterial process.
Pectolytic enzymes are added to fruit musts for fruit wine mainly to
A. Raise juice yield and prevent pectin haze
Pectinases break down pectin, improving pressing yield and clarity. Pectin is not glucose, pectinase can increase methanol rather than reduce it, and it is not a colouring treatment.
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