Parboiled paddy usually gives a higher head rice yield on milling than raw paddy of the same variety. Which change during parboiling is chiefly responsible?

Starch gelatinises during steaming and, on drying, seals cracks and binds the endosperm into a hard, tough kernel

Soaking dissolves the proteins binding the husk, so the husk comes off without stressing the grain in the sheller

Starch gelatinises during steaming and, on drying, seals cracks and binds the endosperm into a hard, tough kernel

Thiamine and other vitamins migrate from the bran into the endosperm, where they strengthen the starch granules

Steaming removes most of the bran oil, so the grain needs much less polishing to reach the required whiteness

Sliced white bread kept in a refrigerator at 4 °C firms faster than the same bread kept at 25 °C, although it loses less moisture. What best explains this?

Amylopectin retrogradation, the main cause of crumb firming, proceeds faster at refrigerator temperatures than at room temperature

Gluten proteins keep cross-linking in the cold through disulphide bonds formed by residual yeast activity in the crumb

Moisture migrates from crumb to crust much faster at 4 °C, so the crumb dries out even though the total moisture is retained

At 4 °C the fat in the bread forms large crystals, and this, rather than any change in the starch, is the main cause of the firming

Which of the following statements about extruded foods, meat analogues and plant-based milks are correct?

High-moisture extrusion through a long cooling die aligns plant proteins into a fibrous, meat-like structure

The expansion of an extruded maize snack at the die is caused by superheated water flashing to steam as the pressure drops

High-moisture extrusion through a long cooling die aligns plant proteins into a fibrous, meat-like structure

The expansion of an extruded maize snack at the die is caused by superheated water flashing to steam as the pressure drops

Soybeans are ground in cold water so as to preserve lipoxygenase, which removes the beany flavour of soy milk

Oat- and almond-based drinks naturally contain more protein than cow milk and so are not fortified

A fat manufacturer replaces partially hydrogenated soybean oil with a blend made by interesterifying fully hydrogenated soybean oil with liquid soybean oil. Why does the new fat contain far less trans fatty acid?

Full hydrogenation leaves almost no double bonds to isomerise, and interesterification only moves fatty acids among glycerol positions

Interesterification converts trans double bonds back to the cis form through the action of the lipase used as the catalyst

The nickel catalyst of full hydrogenation adds hydrogen to cis bonds but cannot act on trans bonds, so these are removed in refining

Liquid soybean oil contains natural cis isomers that neutralise the trans fatty acids formed during hydrogenation when the two fats are blended

Full hydrogenation leaves almost no double bonds to isomerise, and interesterification only moves fatty acids among glycerol positions

One processor makes tomato ketchup and wants maximum consistency; another makes tomato juice and wants the freshest colour and flavour. Which choice of break suits both?

Hot break for the ketchup, because rapid heating inactivates pectic enzymes before they degrade pectin; cold break for the juice

Cold break for the ketchup, because pectin methylesterase activated near 65 °C thickens the pulp considerably; hot break for the juice

Hot break for both, because a cold break leaves polyphenol oxidase active, which blackens tomato products within hours

Hot break for the ketchup, because rapid heating inactivates pectic enzymes before they degrade pectin; cold break for the juice

Cold break for both, because a hot break destroys most of the lycopene, so ketchup and juice alike lose their red colour

Green tea and black tea can be made from the same tea shoots. Which processing difference explains why green tea retains most of its catechins?

Its leaves are steamed or pan-fired early, inactivating polyphenol oxidase before rolling ruptures the cells

It is fermented by yeasts for a longer period, and the yeasts convert the theaflavins back into catechins

It is made from older leaves that contain no polyphenol oxidase, unlike the bud and two leaves used for black tea

It skips withering, and withering is the step in which the catechins are converted to thearubigins

A food company needs a black-pepper extract that delivers both the aroma and the pungency of the spice. Which product should it choose, and why?

Pepper oleoresin, because solvent extraction carries the non-volatile pungent piperine along with the volatile oil

Pepper essential oil, because steam distillation recovers the piperine together with all the aroma compounds

Pepper essential oil, because the pungency resides in the volatile terpenes that steam distillation recovers and concentrates

Pepper oleoresin, because solvent extraction carries the non-volatile pungent piperine along with the volatile oil

Cryogenically ground pepper, because liquid nitrogen selectively extracts the piperine from the ground spice

Beef sides chilled to 2 °C within two hours of slaughter turn out much tougher than sides chilled slowly. Which measure applied at slaughter would best prevent this toughening while still allowing rapid chilling?

Electrical stimulation of the carcass, which speeds glycolysis and ATP depletion so rigor sets before the muscle is cold

Freezing the carcass at once to −20 °C, which locks the muscle in its relaxed pre-rigor state until it is cooked

Electrical stimulation of the carcass, which speeds glycolysis and ATP depletion so rigor sets before the muscle is cold

Injecting a nitrite brine, which binds myoglobin and so prevents the calcium release that makes chilled muscle contract

Holding the animals without feed or water for two days beforehand, so they reach slaughter with low muscle glycogen

Which of the following statements about milk products are correct?

Chymosin in rennet cleaves κ-casein, destabilising the casein micelles so that they coagulate in the presence of calcium

Churning converts an oil-in-water emulsion (cream) into a water-in-oil emulsion (butter)

Chymosin in rennet cleaves κ-casein, destabilising the casein micelles so that they coagulate in the presence of calcium

Churning converts an oil-in-water emulsion (cream) into a water-in-oil emulsion (butter)

Paneer is coagulated with rennet and then ripened for several weeks to develop its flavour

Homogenisation enlarges the fat globules so that the cream rises faster and can be skimmed off easily

The “fishy” odour that develops in marine fish stored too long in ice is mainly due to which compound?

Trimethylamine, formed when spoilage bacteria reduce the trimethylamine oxide present in the flesh

Histamine, formed when lactic acid bacteria decarboxylate the free histidine present in all marine fish

Hydrogen sulphide, formed when the lipids of the fish are oxidised by atmospheric oxygen during storage

Ammonia, formed when the muscle glycogen of the fish is broken down anaerobically after death

Trimethylamine, formed when spoilage bacteria reduce the trimethylamine oxide present in the flesh

In a HACCP plan for HTST pasteurisation of milk, the requirement that the milk be held at not less than 72 °C for 15 s is an example of which element?

A critical limit, the criterion that separates acceptable from unacceptable at a critical control point

A prerequisite programme, a general hygiene condition that applies across the whole of the processing plant

A verification activity, the periodic check confirming that the HACCP plan is working as it was intended

A corrective action, the step taken when monitoring shows that control at the CCP has been lost

Which of the following statements about food-plant sanitation and cleaning in place (CIP) are correct?

In dairy CIP, a hot alkali wash removes fat and protein, and an acid wash removes mineral deposits such as milkstone

CIP cleans closed equipment by circulating rinses and detergent solutions through it without dismantling it

In dairy CIP, a hot alkali wash removes fat and protein, and an acid wash removes mineral deposits such as milkstone

Chlorine sanitisers work best when applied before cleaning, because the organic soil protects them from decomposition

CIP cleans closed equipment by circulating rinses and detergent solutions through it without dismantling it

Once the detergent concentration is fixed, raising the cleaning temperature has no effect on cleaning efficiency

The Food Safety and Standards Act, 2006 is significant for Indian food regulation chiefly because it:

consolidated earlier laws and orders, such as the PFA Act and the Fruit Products Order, under one authority, FSSAI

created the Agmark grading scheme for agricultural produce and at the same time abolished the Bureau of Indian Standards

consolidated earlier laws and orders, such as the PFA Act and the Fruit Products Order, under one authority, FSSAI

made Codex Alimentarius standards directly binding on Indian food businesses in place of any national standards

introduced the Fruit Products Order for the first time, making a licence compulsory for fruit processors

Food Products Technology: Cereals, Oils, Fruits, Plantation Crops, Milk, Meat, Waste Utilisation and Food Standards

This chapter completes Section XL5.3, “Food Products Technology”, of XL5 Food Technology by answering its commodity items: “Cereal processing and products” with “Meat Analogue and Plant-based milk alternatives”, “Oil Processing”, “Fruits and Vegetables Processing”, “Plantation crops processing and products”, “Milk and Milk Products Processing”, “Processing of animal products”, “Waste Utilization”, and “Food standards and Quality Maintenance: FPO, PFA, A-Mark, HACCP, food plant sanitation and cleaning in place (CIP). FSSAI, BIS, Codex Alimentarius, ISO, Food Safety and Management System (FSMS).” For each commodity it follows the process line and asks why each step is there. The numericals are milling yield, oil recovery, the sugar balance of jam, milk standardisation by the Pearson square and ice-cream overrun.

1. Milling of rice, wheat, maize and pulses; parboiling

Rice milling: cleaned paddy is dehusked, mostly by a rubber-roll sheller (two rolls at different speeds shear the husk off); husk is roughly a fifth of paddy mass. The brown rice is whitened in abrasive or friction polishers that remove bran and germ. Milled rice is graded into head rice (whole kernels, or pieces commonly at least three-quarters of a kernel) and brokens; head rice yield, as a percentage of paddy, decides the mill’s income. Parboiling (soaking, steaming, drying, then milling) gelatinises the starch, which seals cracks and fuses the endosperm, so breakage falls and head rice yield rises; water-soluble vitamins such as thiamine migrate inward from the bran, so milled parboiled rice is more nutritious; the grain becomes harder, slightly darker and slower to cook, and its bran richer in oil. Hot soaking shortens soaking and avoids the off-odour of long cold soaks.

Wheat is cleaned and conditioned (water added, then rested), which toughens the bran so it comes off in large flakes and mellows the endosperm. Corrugated break rolls open the kernel and scrape endosperm from bran, sifters and purifiers grade and clean the stock, and smooth reduction rolls grind it to flour. White flour (maida) is typically about 70–75% of the wheat (the extraction rate); chakki atta keeps nearly the whole grain, and suji is coarse endosperm. Maize is dry-milled after degermination into grits, meal and flour, or wet-milled: kernels are steeped in warm water with SO₂, which loosens the protein matrix around the starch and checks unwanted fermentation, and then germ (for oil), fibre, gluten (for feed) and starch (for syrups) are separated. Pulses are dehulled and split (dal milling) after oil and water treatments and drying loosen the husk; gum-bound pigeon pea husk is the hardest.

2. Bread, biscuits, extruded foods, breakfast cereals, meat analogues and plant-based milks

Bread needs strong flour: on mixing, gliadins (extensibility) and glutenins (elasticity) form the gluten network that traps the CO₂ of yeast fermentation. After fermentation, moulding and proofing, baking expands the gas (oven spring), gelatinises starch and sets the crumb, while Maillard reactions and caramelisation brown the crust. Staling is mainly retrogradation of amylopectin, not drying: it is fastest at refrigerator temperatures, reversed briefly by reheating, slowed by emulsifiers and maltogenic amylase, and stopped by freezing. Calcium propionate checks mould and rope (Bacillus). Biscuits use soft, low-protein flour with much sugar and fat, which limit gluten development, chemical leavening (sodium or ammonium bicarbonate) and baking to a few per cent moisture.

Extrusion cooking forces moist starchy or protein-rich material through a heated screw barrel and a die; shear, heat and pressure gelatinise starch, denature proteins and destroy enzymes and many anti-nutrients within a minute or two. At the die the pressure drops suddenly, superheated water flashes to steam and the melt puffs into an expanded snack. Ready-to-eat breakfast cereals are flaked (cooked maize grits rolled into flakes and toasted), gun-puffed (sudden release of pressure), shredded or extruded. Meat analogues texturise soy, pea or wheat proteins: low-moisture extrusion gives spongy, dried textured vegetable protein for rehydration, while high-moisture extrusion through a long cooling die aligns protein into muscle-like fibres; binders such as methylcellulose, fat and colour complete them. Plant-based milks are made by soaking, wet grinding, filtering, formulating, homogenising and UHT treatment. Soybeans are ground hot to inactivate lipoxygenase and reduce beany flavour, and cooking destroys trypsin inhibitors; oat drinks are treated with amylase to thin and sweeten the starch. Except soy, most carry far less protein than cow milk and are fortified with calcium and vitamins B₁₂ and D.

3. Oil processing: expelling, solvent extraction, refining and hydrogenation

Oilseeds are cleaned, dehulled where useful, flaked and cooked, then expelled in a continuous screw press, which leaves a cake still holding several per cent oil. Solvent extraction with food-grade hexane leaves under about 1% in the meal, so low-oil seeds such as soybean and rice bran are extracted directly, while high-oil seeds (groundnut, sunflower, mustard) are pre-pressed and then extracted. Hexane is recovered from the miscella by distillation and from the meal by desolventising and toasting. Hydrogenation adds hydrogen across C=C bonds over a nickel catalyst at high temperature, lowering the iodine value and raising melting point and oxidative stability, so liquid oils become plastic fats such as vanaspati and shortening. Partial hydrogenation also isomerises remaining double bonds from cis to trans, and trans fat raises LDL cholesterol, so regulators, FSSAI among them, now limit it. Fully hydrogenated fat has almost no double bonds left, and interesterification (chemical or lipase-catalysed) rearranges fatty acids on glycerol to adjust melting without creating trans isomers.

Steps of chemical refining of crude oil
Step	Removes	How
Degumming	Phospholipids (gums), recovered as lecithin	Water or dilute acid
Neutralisation	Free fatty acids, as soapstock	Dilute NaOH (physical refining steam-strips FFA instead)
Bleaching	Pigments, traces of soap and metals	Adsorption on activated earth or carbon
Deodorisation	Volatile odour compounds and residual FFA	Steam stripping at high temperature under high vacuum
Winterisation	Waxes and high-melting glycerides	Slow chilling, then filtration

4. Fruit and vegetable products

Juice is extracted by crushing and pressing, with pectinase raising the yield. For a clear juice (apple, grape), pectinase depectinises it so cloud particles flocculate, then fining, centrifugation and filtration follow. A cloudy juice (orange) is heated early to inactivate pectin methylesterase, which would otherwise de-esterify pectin and let calcium pectate settle the cloud. Juice is concentrated in vacuum evaporators after its aroma is stripped and recovered (or by freeze concentration or reverse osmosis) and packed hot-filled, aseptically or frozen.

Jam is fruit pulp boiled with sugar to about 68 °Brix. A high-methoxyl pectin gel needs roughly 0.5–1% pectin, sugar above about 55% to draw water from the pectin, and pH around 3 to suppress the charge on its carboxyl groups; low-methoxyl pectin gels through calcium bridges and suits low-sugar products. The end point is judged by refractometer, boiling point (about 105 °C) or sheet test. Too little acid or pectin gives a runny set, excess acid gives syneresis (weeping), and too little inversion of sucrose lets it crystallise. Jelly is set from a clear, strained extract; marmalade is a citrus jelly with suspended shreds of peel. Squash is a juice-based concentrate diluted before drinking and preserved with KMS or benzoate. Candied fruit is steeped in syrup of gradually rising concentration (strong syrup at once shrivels it), drained, then glazed or crystallised.

Tomato products start with a hot break (crushed tomatoes heated rapidly to about 85–95 °C), which inactivates pectin methylesterase and polygalacturonase before they degrade pectin and so gives the high consistency wanted in paste and ketchup; a cold break (about 60–70 °C) keeps fresher colour and flavour but gives a thinner product, suited to juice. Pulp freed of skins and seeds is purée, concentrated further to paste; ketchup and sauce add sugar, salt, vinegar and spices. Potato chips need tubers high in dry matter and low in reducing sugars: storage near 4 °C causes cold-induced sweetening, so chips fry dark and form more acrylamide (from asparagine and reducing sugars), which reconditioning at about 20 °C reduces. Pickles rely on salt (which favours lactic fermentation), vinegar or an oil layer that excludes air.

5. Tea, coffee, cocoa, spices, essential oils and oleoresins

Black tea: shoots (two leaves and a bud) are withered to lose moisture and become flaccid, then rolled (orthodox) or cut by CTC (crush–tear–curl) machines to rupture cells. In “fermentation”, which is enzymatic oxidation and not microbial, polyphenol oxidase oxidises catechins to theaflavins and thearubigins; hot-air firing then stops the enzymes. Green tea is steamed or pan-fired first, so the enzymes die and catechins stay unoxidised; oolong is partly oxidised. Coffee cherries are processed dry (whole cherries sun-dried, then hulled) or wet (pulped, the pectin-rich mucilage removed by natural fermentation, washed and dried as parchment, then hulled to green beans). Roasting at roughly 200–240 °C builds colour and aroma through Maillard reactions, caramelisation and pyrolysis and releases CO₂; instant coffee is a spray- or freeze-dried extract.

Cocoa beans are fermented with their pulp in heaps or boxes for several days: yeasts and then lactic and acetic acid bacteria work on the pulp, and the acid and heat kill the bean and let its enzymes form flavour precursors (peptides, amino acids, sugars) that react on roasting. Dried beans are roasted and winnowed to nibs, ground to cocoa liquor and pressed into cocoa butter and cake for powder. Chocolate is refined, conched (long mixing that drives off volatile acids and smooths texture) and tempered so cocoa butter crystallises in its stable form V, giving gloss and snap; poor tempering or warm storage causes fat bloom. Spices lose volatile oil to grinding heat, so cryogenic grinding with liquid nitrogen preserves aroma. Essential oils, the volatile aroma fraction, are obtained by steam distillation; oleoresins by solvent extraction and removal of the solvent, so they carry the volatile oil plus non-volatile pungent and colouring principles such as piperine of pepper, capsaicin of chilli, gingerols of ginger and curcumin of turmeric.

6. Milk and milk products

Cow milk is roughly 87% water, 4% fat, 3.3% protein (mostly casein) and 4.8% lactose; buffalo milk is richer in fat. At the dairy, milk is chilled, clarified, separated in a centrifugal separator (by Stokes’ law, separation speed rises with the square of globule diameter), standardised, homogenised (forced through a narrow valve at high pressure so globules fall to about 1 µm and no cream line forms) and heat-treated: pasteurised (63 °C/30 min or 72 °C/15 s) or UHT-treated and aseptically packed.

🧠 Pearson square

To mix milk of fat A% with milk of fat B% to reach C% (A > C > B), take (C − B) parts of the first and (A − C) parts of the second. For 6.0% buffalo milk and 0.1% skim milk to give 4.5%: 4.4 parts to 1.5, so 100 kg of buffalo milk takes 100 × 1.5/4.4 = 34.1 kg skim.

Butter: cream is pasteurised, aged cold to crystallise fat and churned, which breaks globule membranes so fat clumps into grains; this is a phase inversion from an oil-in-water emulsion (cream) to a water-in-oil one (butter, about 80% fat), and buttermilk drains away. Ghee is made by heating butter or cream to about 110–120 °C, which drives off water and browns the milk solids (the residue) to give its flavour; it is nearly pure fat. Ice cream mix (fat, milk solids-not-fat, sugar, stabiliser, emulsifier) is pasteurised, homogenised, aged near 4 °C, frozen in a scraped-surface freezer while air is whipped in, and hardened well below −20 °C. Overrun = (volume of ice cream − volume of mix) ÷ volume of mix × 100; for equal volumes it equals (mass of mix − mass of ice cream) ÷ mass of ice cream × 100. Cheese: rennet’s chymosin cleaves κ-casein at the Phe105–Met106 bond, the destabilised micelles clot with calcium, and the curd is cut, cooked, drained, salted, pressed and ripened; paneer, in contrast, is coagulated by acid and heat and not ripened. Milk powder is made by vacuum evaporation and then spray drying or roller drying (more heat damage, lower solubility).

7. Meat, poultry and fish processing

Slaughter runs: rest in lairage (to restore muscle glycogen), ante-mortem inspection, stunning, bleeding, skinning or dehairing, evisceration, post-mortem inspection and chilling. After death ATP runs out and actin and myosin lock in rigor mortis; glycolysis lowers the pH from about 7 to an ultimate pH near 5.5, and ageing then tenderises by proteolysis (calpains). Stress before slaughter depletes glycogen, leaving a high ultimate pH and DFD (dark, firm, dry) meat that spoils fast; a very rapid pH fall while the carcass is still hot, typical of stress-susceptible pigs, gives PSE (pale, soft, exudative) meat. Chilling beef or lamb below about 10 °C before rigor causes cold shortening and toughness; electrical stimulation speeds glycolysis so that rigor sets before the muscle is cold. Poultry are stunned, killed, bled, scalded in hot water to loosen feathers, defeathered, eviscerated and chilled in cold water or air.

Curing uses salt, nitrite (or nitrate reduced to it), sugar and ascorbate: nitrite releases NO, which forms pink nitrosyl myoglobin, gives cured flavour, retards rancidity and inhibits C. botulinum; ascorbate speeds colour formation and limits nitrosamines. Smoking dries and flavours: smoke phenols are antioxidant and antimicrobial and carbonyls brown the surface; cold smoking does not cook, hot smoking does, and polycyclic aromatic hydrocarbons such as benzo[a]pyrene are the hazard. Fish spoils fastest: little glycogen leaves a high post-mortem pH, bacteria reduce TMAO to fishy TMA, highly unsaturated lipids go rancid, and in tuna and mackerel temperature abuse converts histidine to histamine (scombroid poisoning). Fish is iced, frozen (plate or blast, then glazed with a thin ice layer), canned with a full low-acid process, dried or salted, smoked, or made into ready-to-eat surimi products (washed mince with sugar and sorbitol as cryoprotectants, set into gels); meat likewise gives frozen, canned, dried and ready-to-eat products (sausages, hams, nuggets).

8. Waste utilisation

Pectin is extracted from citrus peel and apple pomace with hot dilute acid, precipitated with alcohol, washed, dried and milled; controlled de-esterification turns high-methoxyl into low-methoxyl grades. Rice milling by-products are husk (boiler fuel; its silica-rich ash goes into cement and insulation), bran (heat-stabilised quickly because its lipase soon raises free fatty acids, then extracted for rice bran oil, the de-oiled bran going to feed) and broken rice (flour, starch, snacks, brewing). Edible films and coatings are made from by-product biopolymers such as whey protein, gelatin from skins and bones, zein from maize, chitosan from crustacean shells (also antimicrobial), starch and pectin, plasticised with glycerol or sorbitol; they are good oxygen barriers but poor moisture barriers unless lipid is added. Bagasse, areca-leaf and starch-based or PLA materials replace some plastic packaging.

9. Food standards, HACCP, sanitation and CIP

India’s earlier food laws included the Prevention of Food Adulteration (PFA) Act, 1954 and the Fruit Products Order (FPO), 1955, whose FPO mark was compulsory on processed fruit and vegetable products, among other orders. The Food Safety and Standards Act, 2006 consolidated these laws and orders into one system administered by the Food Safety and Standards Authority of India (FSSAI), which sets standards, licenses food businesses and expects them to run a food safety management system (FSMS) plan built on good hygiene and manufacturing practices. Agmark, under the Agricultural Produce (Grading and Marking) Act, 1937, certifies grades of agricultural commodities such as pulses, spices, ghee and honey. The Bureau of Indian Standards (BIS) is the national standards body whose ISI mark certifies conformity to Indian Standards. Internationally, the Codex Alimentarius Commission of FAO and WHO issues food standards and codes of practice, and ISO 22000 specifies an FSMS combining HACCP, prerequisite programmes and management-system requirements.

HACCP is preventive: instead of testing finished products it controls biological, chemical and physical hazards (and allergens) where they arise. Its seven principles:
(1) conduct a hazard analysis;
(2) determine the critical control points (CCPs), steps where control is essential to prevent, eliminate or reduce a hazard to an acceptable level;
(3) set critical limits (for example 72 °C for 15 s);
(4) monitor;
(5) set corrective actions;
(6) verify;
(7) keep records. Sanitation first removes soil (cleaning) and then reduces microbes to safe levels (sanitising); chlorine is quickly used up by organic soil, so it works only on clean surfaces. Cleaning depends on time, mechanical action, chemical concentration and temperature. Cleaning in place (CIP) circulates solutions through closed equipment without dismantling it, at turbulent velocity: water pre-rinse, hot alkali (NaOH) for fat and protein, rinse, acid (nitric or phosphoric) for mineral scale such as milkstone, final rinse, then sanitising with hot water, chlorine or peracetic acid.

Key takeaways

Rice: husk is about a fifth of paddy, and parboiling raises head rice yield by gelatinising starch. Wheat is conditioned, broken on corrugated rolls and reduced on smooth ones.
Bread stales by amylopectin retrogradation, fastest when chilled; extruded snacks expand as superheated water flashes; high-moisture extrusion makes fibrous meat analogues.
Expelling leaves several per cent oil, hexane under 1%; refining is degumming, neutralisation, bleaching and deodorisation; partial hydrogenation makes trans fat, interesterification does not.
High-methoxyl pectin gels above about 55% sugar near pH 3; jam is finished near 68 °Brix; hot break thickens tomato paste. Tea “fermentation” is PPO oxidation; oleoresins carry pungency, essential oils only aroma.
Pearson square: (C − B) parts of richer to (A − C) of leaner milk. Churning inverts cream to butter; chymosin cuts κ-casein. Electrical stimulation prevents cold shortening; fishy odour is TMA.
The FSS Act, 2006 consolidated the PFA Act, the FPO and other orders under FSSAI. HACCP has seven principles; CIP runs rinse, alkali, rinse, acid, rinse, sanitise.

Practice questions (18)

Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.

A rice mill processes 1000 kg of paddy. The husk is 20% of the paddy mass, the bran and polish removed in whitening are 9% of the brown rice, and broken grains make up 12% of the milled rice. The head rice yield as a percentage of the paddy (to one decimal place) is ____.
Numerical answer — type the value.
Show answer
Answer: 64.1
Brown rice = 1000 × 0.80 = 800 kg. Milled rice = 800 × (1 − 0.09) = 728 kg. Head rice = 728 × (1 − 0.12) = 640.64 kg, i.e. 64.06% ≈ 64.1% of the paddy. Subtracting all the percentages from 100 (100 − 20 − 9 − 12 = 59%) is the usual slip, because each loss is a fraction of a different stream.
Parboiled paddy usually gives a higher head rice yield on milling than raw paddy of the same variety. Which change during parboiling is chiefly responsible?
1. Soaking dissolves the proteins binding the husk, so the husk comes off without stressing the grain in the sheller
2. Starch gelatinises during steaming and, on drying, seals cracks and binds the endosperm into a hard, tough kernel
3. Thiamine and other vitamins migrate from the bran into the endosperm, where they strengthen the starch granules
4. Steaming removes most of the bran oil, so the grain needs much less polishing to reach the required whiteness
Show answer
Answer: B — Starch gelatinises during steaming and, on drying, seals cracks and binds the endosperm into a hard, tough kernel
Gelatinised starch flows into fissures and sets on drying, so the kernel becomes translucent and hard and resists breakage in shelling and whitening. Vitamin migration is a real effect of parboiling, which makes that distractor tempting, but it improves nutrition, not strength. Parboiled bran is in fact richer in oil, and husk removal is not what reduces brokens.
Sliced white bread kept in a refrigerator at 4 °C firms faster than the same bread kept at 25 °C, although it loses less moisture. What best explains this?
1. Amylopectin retrogradation, the main cause of crumb firming, proceeds faster at refrigerator temperatures than at room temperature
2. Gluten proteins keep cross-linking in the cold through disulphide bonds formed by residual yeast activity in the crumb
3. Moisture migrates from crumb to crust much faster at 4 °C, so the crumb dries out even though the total moisture is retained
4. At 4 °C the fat in the bread forms large crystals, and this, rather than any change in the starch, is the main cause of the firming
Show answer
Answer: A — Amylopectin retrogradation, the main cause of crumb firming, proceeds faster at refrigerator temperatures than at room temperature
Staling is mainly the recrystallisation of amylopectin in gelatinised starch; it is faster at chill temperatures than at room temperature and negligible in the frozen state, which is why bread stales fastest in the refrigerator and keeps well frozen. Crumb-to-crust moisture migration does occur, but it is not faster in the cold and cannot explain firming without moisture loss; the yeast is killed in baking, and fat crystallisation is at most a minor contributor.
Which of the following statements about extruded foods, meat analogues and plant-based milks are correct?
1. High-moisture extrusion through a long cooling die aligns plant proteins into a fibrous, meat-like structure
2. The expansion of an extruded maize snack at the die is caused by superheated water flashing to steam as the pressure drops
3. Soybeans are ground in cold water so as to preserve lipoxygenase, which removes the beany flavour of soy milk
4. Oat- and almond-based drinks naturally contain more protein than cow milk and so are not fortified
Show answer
Answer: A — High-moisture extrusion through a long cooling die aligns plant proteins into a fibrous, meat-like structure; B — The expansion of an extruded maize snack at the die is caused by superheated water flashing to steam as the pressure drops
Cooling the protein melt in a long die while it flows aligns it into fibres, the basis of whole-cut meat analogues, and snack expansion comes from the sudden flashing of superheated water at the die. Lipoxygenase produces the beany flavour, so soybeans are ground hot to inactivate it. Oat and almond drinks carry far less protein than cow milk and are commonly fortified with calcium and vitamins.
An oilseed contains 40% oil, the rest being oil-free solids (ignore moisture). Expelling alone leaves a cake containing 7.0% oil, whereas solvent extraction leaves a meal containing 1.0% oil, both on the mass of the cake or meal. Assuming all oil-free solids end up in the cake or meal, the additional oil recovered per 1000 kg of seed by solvent extraction compared with expelling (kg, to one decimal place) is ____.
Numerical answer — type the value.
Show answer
Answer: 39.1
Oil-free solids = 600 kg. Cake: residual oil x satisfies x/(600 + x) = 0.07, so x = 0.07 × 600/0.93 = 45.16 kg. Meal: x = 0.01 × 600/0.99 = 6.06 kg. Extra oil recovered = 45.16 − 6.06 = 39.10 ≈ 39.1 kg. Taking 7% and 1% of the 1000 kg of seed (70 − 10 = 60 kg) is the common slip, since the percentages refer to the cake and meal.
A fat manufacturer replaces partially hydrogenated soybean oil with a blend made by interesterifying fully hydrogenated soybean oil with liquid soybean oil. Why does the new fat contain far less trans fatty acid?
1. Interesterification converts trans double bonds back to the cis form through the action of the lipase used as the catalyst
2. The nickel catalyst of full hydrogenation adds hydrogen to cis bonds but cannot act on trans bonds, so these are removed in refining
3. Liquid soybean oil contains natural cis isomers that neutralise the trans fatty acids formed during hydrogenation when the two fats are blended
4. Full hydrogenation leaves almost no double bonds to isomerise, and interesterification only moves fatty acids among glycerol positions
Show answer
Answer: D — Full hydrogenation leaves almost no double bonds to isomerise, and interesterification only moves fatty acids among glycerol positions
Trans isomers form when a double bond is partly hydrogenated and re-forms in the trans configuration; fully hydrogenated stock is essentially saturated, so it has almost none. Interesterification randomises fatty acids on glycerol, softening the hard stock with liquid oil, without touching the double bonds, so no new trans isomers form. It does not convert trans bonds to cis, and blending cannot cancel isomers already present.
A jam batch is made from 60 kg of fruit pulp of 12 °Brix and 54 kg of sucrose and is boiled until it reaches 68 °Brix. Treating all soluble solids as coming from the pulp and the sucrose and ignoring other losses, the mass of water evaporated (kg) is ____.
Numerical answer — type the value.
Show answer
Answer: 24
Soluble solids = 60 × 0.12 + 54 = 7.2 + 54 = 61.2 kg, and they are conserved. Final jam = 61.2/0.68 = 90.0 kg. Initial mass = 60 + 54 = 114 kg, so water evaporated = 114 − 90 = 24 kg. Forgetting the solids of the pulp gives 54/0.68 = 79.4 kg of jam and a wrong 34.6 kg.
One processor makes tomato ketchup and wants maximum consistency; another makes tomato juice and wants the freshest colour and flavour. Which choice of break suits both?
1. Cold break for the ketchup, because pectin methylesterase activated near 65 °C thickens the pulp considerably; hot break for the juice
2. Hot break for both, because a cold break leaves polyphenol oxidase active, which blackens tomato products within hours
3. Hot break for the ketchup, because rapid heating inactivates pectic enzymes before they degrade pectin; cold break for the juice
4. Cold break for both, because a hot break destroys most of the lycopene, so ketchup and juice alike lose their red colour
Show answer
Answer: C — Hot break for the ketchup, because rapid heating inactivates pectic enzymes before they degrade pectin; cold break for the juice
Heating crushed tomatoes quickly to about 85–95 °C inactivates pectin methylesterase and polygalacturonase before they break down pectin, so the product keeps its viscosity, which suits paste and ketchup. A cold break (about 60–70 °C) lets these enzymes act, giving a thinner product, but it is gentler on colour and fresh flavour, which suits juice. In tomato pulp pectin methylesterase prepares pectin for breakdown by polygalacturonase, so it thins rather than thickens; lycopene is fairly heat-stable, and polyphenol oxidase browning is not what limits tomato products.
Green tea and black tea can be made from the same tea shoots. Which processing difference explains why green tea retains most of its catechins?
1. Its leaves are steamed or pan-fired early, inactivating polyphenol oxidase before rolling ruptures the cells
2. It is fermented by yeasts for a longer period, and the yeasts convert the theaflavins back into catechins
3. It is made from older leaves that contain no polyphenol oxidase, unlike the bud and two leaves used for black tea
4. It skips withering, and withering is the step in which the catechins are converted to thearubigins
Show answer
Answer: A — Its leaves are steamed or pan-fired early, inactivating polyphenol oxidase before rolling ruptures the cells
In black tea, rolling or CTC brings polyphenol oxidase into contact with catechins, which are oxidised to theaflavins and thearubigins during “fermentation”. Steaming or pan-firing green tea first kills the enzyme, so rolling does not trigger oxidation. Tea “fermentation” is enzymatic, not microbial, and the oxidation follows rolling rather than withering.
A food company needs a black-pepper extract that delivers both the aroma and the pungency of the spice. Which product should it choose, and why?
1. Pepper essential oil, because steam distillation recovers the piperine together with all the aroma compounds
2. Pepper essential oil, because the pungency resides in the volatile terpenes that steam distillation recovers and concentrates
3. Pepper oleoresin, because solvent extraction carries the non-volatile pungent piperine along with the volatile oil
4. Cryogenically ground pepper, because liquid nitrogen selectively extracts the piperine from the ground spice
Show answer
Answer: C — Pepper oleoresin, because solvent extraction carries the non-volatile pungent piperine along with the volatile oil
Piperine, the pungent principle, is non-volatile, so it stays behind in steam distillation; the essential oil has the aroma but little bite. Solvent extraction followed by removal of the solvent gives an oleoresin carrying both the volatile oil and the non-volatile pungent resin. Cryogenic grinding is a way of grinding that keeps volatile oil, not an extraction method.
A dairy wants to standardise 400 kg of buffalo milk containing 6.5% fat to 3.0% fat by adding skim milk containing 0.1% fat. Using the Pearson square (a fat balance), the mass of skim milk to be added (kg, to one decimal place) is ____.
Numerical answer — type the value.
Show answer
Answer: 482.8
Parts of buffalo milk = 3.0 − 0.1 = 2.9; parts of skim milk = 6.5 − 3.0 = 3.5. Skim milk = 400 × 3.5/2.9 = 482.76 ≈ 482.8 kg. Check: fat = 26.0 + 0.48 = 26.48 kg in 882.8 kg, which is 3.0%.
A 2.0 L cup filled with ice-cream mix weighs 2.20 kg (net), and the same cup filled with the frozen ice cream made from that mix weighs 1.16 kg (net). The overrun (%, to one decimal place) is ____.
Numerical answer — type the value.
Show answer
Answer: 89.7
For equal volumes, overrun = (mass of mix − mass of ice cream)/mass of ice cream × 100 = (2.20 − 1.16)/1.16 × 100 = 89.7%; equivalently, a given mass of mix occupies 2.20/1.16 = 1.897 times its volume after freezing. Dividing by the mass of the mix (giving 47.3%) is the usual error.
Beef sides chilled to 2 °C within two hours of slaughter turn out much tougher than sides chilled slowly. Which measure applied at slaughter would best prevent this toughening while still allowing rapid chilling?
1. Freezing the carcass at once to −20 °C, which locks the muscle in its relaxed pre-rigor state until it is cooked
2. Electrical stimulation of the carcass, which speeds glycolysis and ATP depletion so rigor sets before the muscle is cold
3. Injecting a nitrite brine, which binds myoglobin and so prevents the calcium release that makes chilled muscle contract
4. Holding the animals without feed or water for two days beforehand, so they reach slaughter with low muscle glycogen
Show answer
Answer: B — Electrical stimulation of the carcass, which speeds glycolysis and ATP depletion so rigor sets before the muscle is cold
Pre-rigor muscle chilled below about 10 °C releases calcium while ATP is still present and contracts strongly: cold shortening. Electrical stimulation exhausts ATP quickly, so rigor is complete before the muscle becomes cold. Immediate freezing invites thaw rigor, which is worse; nitrite has no effect on calcium release; and depleting glycogen yields DFD meat rather than preventing shortening.
Which of the following statements about milk products are correct?
1. Chymosin in rennet cleaves κ-casein, destabilising the casein micelles so that they coagulate in the presence of calcium
2. Churning converts an oil-in-water emulsion (cream) into a water-in-oil emulsion (butter)
3. Paneer is coagulated with rennet and then ripened for several weeks to develop its flavour
4. Homogenisation enlarges the fat globules so that the cream rises faster and can be skimmed off easily
Show answer
Answer: A — Chymosin in rennet cleaves κ-casein, destabilising the casein micelles so that they coagulate in the presence of calcium; B — Churning converts an oil-in-water emulsion (cream) into a water-in-oil emulsion (butter)
Chymosin cuts κ-casein at Phe105–Met106, removing the hairy layer that keeps micelles apart, and calcium then clots them. Churning damages globule membranes so fat clumps and the emulsion inverts from oil-in-water to water-in-oil. Paneer is set by acid and heat and eaten fresh, not ripened, and homogenisation breaks globules down to about 1 µm precisely so that cream does not rise.
The “fishy” odour that develops in marine fish stored too long in ice is mainly due to which compound?
1. Histamine, formed when lactic acid bacteria decarboxylate the free histidine present in all marine fish
2. Hydrogen sulphide, formed when the lipids of the fish are oxidised by atmospheric oxygen during storage
3. Ammonia, formed when the muscle glycogen of the fish is broken down anaerobically after death
4. Trimethylamine, formed when spoilage bacteria reduce the trimethylamine oxide present in the flesh
Show answer
Answer: D — Trimethylamine, formed when spoilage bacteria reduce the trimethylamine oxide present in the flesh
Marine fish contain TMAO, which spoilage bacteria such as Shewanella use as an electron acceptor, reducing it to volatile, fishy-smelling TMA, a standard spoilage index. Histamine is the scombroid toxin of histidine-rich fish such as tuna and mackerel under temperature abuse, not the usual cause of fishy odour; lipid oxidation gives rancid, not sulphide, odours; and glycogen breakdown gives lactic acid, not ammonia.
In a HACCP plan for HTST pasteurisation of milk, the requirement that the milk be held at not less than 72 °C for 15 s is an example of which element?
1. A critical limit, the criterion that separates acceptable from unacceptable at a critical control point
2. A prerequisite programme, a general hygiene condition that applies across the whole of the processing plant
3. A verification activity, the periodic check confirming that the HACCP plan is working as it was intended
4. A corrective action, the step taken when monitoring shows that control at the CCP has been lost
Show answer
Answer: A — A critical limit, the criterion that separates acceptable from unacceptable at a critical control point
Pasteurisation is a CCP, and the time–temperature combination that must be met there is its critical limit. Prerequisite programmes are plant-wide hygiene conditions, not a step-specific criterion; verification (for example, calibrating the thermometer or reviewing charts) checks the system; corrective action (diverting under-heated milk) is what happens when the limit is breached.
Which of the following statements about food-plant sanitation and cleaning in place (CIP) are correct?
1. In dairy CIP, a hot alkali wash removes fat and protein, and an acid wash removes mineral deposits such as milkstone
2. Chlorine sanitisers work best when applied before cleaning, because the organic soil protects them from decomposition
3. CIP cleans closed equipment by circulating rinses and detergent solutions through it without dismantling it
4. Once the detergent concentration is fixed, raising the cleaning temperature has no effect on cleaning efficiency
Show answer
Answer: A — In dairy CIP, a hot alkali wash removes fat and protein, and an acid wash removes mineral deposits such as milkstone; C — CIP cleans closed equipment by circulating rinses and detergent solutions through it without dismantling it
Alkali saponifies fat and dissolves protein, acid dissolves calcium phosphate scale, and CIP does all this by circulation through closed lines and vessels. Chlorine reacts with organic matter and is used up, so surfaces must be cleaned before they are sanitised. Cleaning efficiency depends jointly on time, mechanical action, concentration and temperature, so temperature matters even at fixed concentration.
The Food Safety and Standards Act, 2006 is significant for Indian food regulation chiefly because it:
1. created the Agmark grading scheme for agricultural produce and at the same time abolished the Bureau of Indian Standards
2. consolidated earlier laws and orders, such as the PFA Act and the Fruit Products Order, under one authority, FSSAI
3. made Codex Alimentarius standards directly binding on Indian food businesses in place of any national standards
4. introduced the Fruit Products Order for the first time, making a licence compulsory for fruit processors
Show answer
Answer: B — consolidated earlier laws and orders, such as the PFA Act and the Fruit Products Order, under one authority, FSSAI
The FSS Act, 2006 replaced and consolidated the Prevention of Food Adulteration Act, 1954, the Fruit Products Order, 1955 and other food orders, and created FSSAI to set standards and license food businesses. Agmark rests on the Agricultural Produce (Grading and Marking) Act, 1937 and BIS continues as the national standards body; the FPO dates from 1955 and was one of the orders the Act replaced; FSSAI frames its own standards rather than adopting Codex wholesale.