Maharashtra HSC Food Products Technology (Vocational) cheat sheet

Water activity (aw) limits: most bacteria stop growing below 0.90, most yeasts below 0.88, most moulds below 0.80; Clostridium botulinum is inhibited below aw 0.93 in anaerobic foods.

Maillard browning needs a reducing sugar plus an amino group and is fastest at aw 0.6–0.8 and pH 6–8; caramelisation instead needs temperatures above about 120°C and no amine.

Casein precipitates at its isoelectric point pH 4.6; whey proteins remain soluble there and are denatured by heating above about 65°C.

Lipid oxidation is measured by peroxide value (meq active oxygen per kg fat, primary products) and by TBA or anisidine value (secondary products); iodine value measures unsaturation.

Starch gelatinises in the 60–70°C range; on cooling, amylose retrogrades and firms the gel, which is the chemistry behind staling of cooked rice and bread.

Enzymatic browning of cut fruit is caused by polyphenol oxidase acting on phenols in the presence of oxygen; ascorbic acid, citric acid, heat or exclusion of oxygen slows it.

Chlorophyll turns olive-brown when heat or acid replaces its magnesium with hydrogen (pheophytin); anthocyanins act as pH indicators, red in acid and blue-green in alkali.

Henderson–Hasselbalch: pH = pKa + log([A−]/[HA]); it sets the pH of an acid–salt buffer such as citrate or acetate used in food systems.

D value = time at a fixed temperature for a 1-log (90%) reduction; z value = the temperature rise that cuts D tenfold, typically about 10°C for bacterial spores.

The 12-D concept for low-acid canned foods targets 12 log reductions of Clostridium botulinum spores, equivalent to F0 ≈ 2.5 min at 121°C.

Homofermentative LAB such as Lactobacillus delbrueckii give almost only lactic acid; heterofermentative Leuconostoc also produce CO2, ethanol and acetic acid.

Idli and dosa batters ferment through Leuconostoc mesenteroides plus yeasts; CO2 from heterolactic fermentation raises the batter and lactic acid lowers pH to about 4.5.

Dahi or curd sets when Lactobacillus bulgaricus or acidophilus and Streptococcus thermophilus lower milk pH to 4.6, the isoelectric point of casein.

Moulds in food fermentation: Aspergillus oryzae for soy sauce and miso, Penicillium roqueforti for blue cheese, Rhizopus for tempeh.

Saccharomyces cerevisiae converts hexose to ethanol and CO2 (C6H12O6 → 2C2H5OH + 2CO2) and is inhibited above about 14–15% ethanol.

Spoilage groupings by temperature: psychrotrophs grow at 0–7°C, mesophiles at 20–45°C, thermophiles at 45–65°C; thermoduric organisms survive heating but do not grow after it.

LTLT pasteurisation = 63°C for 30 min; HTST = 72°C for 15 s; UHT = 135–150°C for 2–5 s followed by aseptic packaging.

Commercial sterility of low-acid canned food is achieved at 115–121°C in a retort; acid foods (pH below 4.6) need only about 100°C.

Blanching at 90–100°C for 1–3 min inactivates peroxidase and polyphenol oxidase; a negative peroxidase test indicates adequate blanching.

Freezing to −18°C stops microbial growth but not all enzyme or chemical change; quick freezing gives small ice crystals and less drip loss on thawing.

Water activity is lowered by drying, salt or sugar addition; the sorption isotherm relates moisture content to aw at constant temperature.

Chemical preservatives: sodium benzoate works below pH 4.5, potassium sorbate over a wider pH range, and sulphur dioxide also controls browning but is residue-limited.

Irradiation doses: 0.05–0.15 kGy for sprout inhibition in potato and onion, 0.15–0.5 kGy for insect disinfestation, up to 10 kGy for some shelf-life extension.

Hurdle technology combines mild factors (chilling, aw, pH, preservative, modified atmosphere) so that no single factor must be severe.

Jam standard: 68% total soluble solids; jelly 65%; marmalade 65%; these FPO limits are checked with a refractometer at 20°C.

A pectin gel needs 0.5–1.0% pectin, 65–68 °Brix and pH 3.0–3.5; high-methoxyl pectin sets with sugar and acid, low-methoxyl pectin sets with calcium.

Squash and cordial need at least 25% fruit juice; squash carries 40–45% TSS and cordial at least 30% TSS with permitted preservative.

Maturity indices include TSS, titratable acidity, firmness, starch–iodine staining and days from anthesis; they decide harvest date and processing quality.

Lye peeling uses 1–2% hot sodium hydroxide; after peeling, fruits are rinsed and dipped in dilute acid to neutralise residual alkali.

Tomato products: juice or puree about 4–5% solids, paste 25–30%, ketchup about 25–28% TSS with 1.0–1.5% salt and 0.5% acetic acid.

Sulphur dioxide from burning sulphur or metabisulphite prevents browning in dried fruits and vegetables but is restricted by FSSAI residue limits.

Canning of fruits uses sugar syrup of 20–40 °Brix; because fruit pH is usually below 4.6, a boiling-water or atmospheric exhaust process is sufficient.

Cow milk ≈ 87% water, 3.5% fat, 8.5% SNF; buffalo milk ≈ 83% water, 6.5–7% fat, 9–10% SNF, so buffalo milk gives higher paneer and ghee yield.

Milk tests: phosphatase for pasteurisation efficiency, MBRT for microbial quality, clot-on-boiling and alcohol test for heat stability, specific gravity 1.026–1.032.

Cream is separated by centrifuge, standardised by Pearson square, and homogenised at 150–200 bar to reduce fat globules below 2 µm.

Butter churning converts cream (35–40% fat) into butter with about 80% fat and 16% moisture; ice cream overrun = (volume of ice cream − volume of mix) × 100 / volume of mix.

Cheddar cheese: rennet coagulates casein, whey is drained, curd is cheddared, milled, salted and pressed; ripening at 5–10°C develops flavour.

Spray drying: milk concentrate at 45–50% solids is atomised into hot air at 150–200°C inlet; outlet air at 80–90°C gives powder below 4% moisture.

Adulteration tests: iodine for starch, rosolic acid for detergent, urease–phenol red for urea, and the Gerber method for fat.

FSSAI milk standards: cow milk minimum 3.5% fat and 8.5% SNF; buffalo milk 6.0% fat and 9.0% SNF, with state rules sometimes stricter.

Ghee is clarified butterfat with not more than 0.5% moisture; Reichert–Meissl value and Butyro-refractometer reading are used to check purity.

Wheat milling separates bran, germ and endosperm; extraction rate = flour weight × 100 / wheat weight; maida is refined flour while atta is whole wheat flour.

Bread flour needs 12–14% protein for gluten strength; biscuit and cake flours use weaker wheat of about 8–10% protein.

Straight-dough bread per 100 kg flour: 60–65 kg water, 1.5–2 kg yeast, 1.5–2 kg salt, 2–4 kg sugar, 2–4 kg fat; ferment 2–3 h at 27–30°C, bake at 220–230°C.

Rice parboiling: soak paddy, steam, dry, then mill; it gelatinises starch, reduces breakage and retains thiamine and riboflavin.

Dal milling removes husk and splits the pulse; pretreatments include soaking, oil or water application and drying to loosen the husk.

Oil extraction by expeller leaves 5–8% oil in cake; solvent extraction with hexane recovers the rest; refining steps are degumming, neutralisation, bleaching and deodorisation.

Hydrogenation raises the melting point and converts liquid oil into vanaspati; it also forms trans fatty acids, which FSSAI limits to 2% of total fat.

Sugar confectionery: crystallisation is controlled by adding invert sugar or glucose syrup; fondant is a supersaturated sucrose solution with fine crystals; caramel is heated sugar without amines.

Anti-nutritional factors: trypsin inhibitor in soybean, phytate in cereals and pulses, tannin in sorghum; soaking, germination, roasting and fermentation reduce them.

Post-mortem pH falls from about 7.0 to 5.5–6.0 as glycogen converts to lactic acid; rigor mortis peaks in 6–24 h and resolves during ageing.

Cold shortening occurs when carcasses are chilled below about 10°C before rigor; PSE meat has a rapid pH fall while warm, DFD meat has a high ultimate pH from pre-slaughter stress.

Curing uses salt, nitrite (typically 120–150 ppm in the product), sugar and ascorbate; nitrite gives cured colour and inhibits Clostridium botulinum.

Fish freshness: ATP degrades to inosine and hypoxanthine; TVB-N above about 30 mg/100 g indicates spoilage; histamine above 50 ppm in scombroid fish causes poisoning.

Egg quality: Haugh unit from thick albumen height, yolk index, and candling to detect cracks, blood spots and staleness; store at 10–13°C and 70–80% RH.

Poultry processing: bleeding, scalding at 52–60°C, plucking, evisceration, pre-chilling to below 4°C within 4 hours, then packaging.

Freezer burn is moisture loss from the surface of frozen meat by sublimation; it causes dry grey patches and is prevented by tight packaging.

Surimi is washed, minced fish myofibrillar protein; added cryoprotectants such as sorbitol and polyphosphate keep it stable at −20°C for kamaboko.

Packaging functions: containment, protection from mechanical, moisture, oxygen, light and microbial hazards, compatibility, convenience and communication.

MAP gas mixtures: red meat 60–80% O2 + 20–40% CO2; poultry and fish 30–60% CO2 with N2; fresh produce 2–5% O2 + 3–8% CO2.

Retort pouches are multilayer laminates (PET/aluminium foil/CPP) able to withstand 121°C; aseptic packaging fills sterilised product into sterilised packs.

Barrier terms: OTR (oxygen transmission rate) and WVTR (water vapour transmission rate) in g/m²/day; aluminium foil and EVOH are high barriers.

Storage systems: cold store 0–4°C, frozen store −18 to −20°C, controlled atmosphere 1–3% O2 and 1–5% CO2 for apples; MA storage uses plastic films.

FIFO and FEFO stock rotation; stacking rules keep 30–45 cm between stacks and walls for air circulation and inspection.

Refrigerated transport (reefer) must maintain the cold chain; fruits and vegetables need ventilation to remove ethylene, while meat and dairy need tight temperature control.

HACCP seven principles: hazard analysis, determine CCPs, set critical limits, monitor, establish corrective actions, verify, and keep records.

A CCP is controlled by a measurable limit such as 72°C for 15 s, pH ≤ 4.6, aw ≤ 0.85 or a metal-detector setting; monitoring records prove control.

Pre-requisite programmes: GMP, GHP, SSOP, pest control, water quality, supplier approval, calibration, traceability and recall.

FSSAI licensing: basic registration up to ₹12 lakh turnover, state licence ₹12 lakh–₹20 crore, central licence above ₹20 crore or for importers and large exporters.

FSSAI label requirements: FSSAI logo and licence number, veg/non-veg mark, ingredient list, nutrition information, net quantity, lot, best-before, storage and allergen declaration.

Indicator organisms: coliforms and E. coli signal hygiene failure; Salmonella, Listeria and Staphylococcus aureus are pathogens tested against FSSAI limits.

Cleaning sequence: dry clean, rinse, detergent wash, rinse, sanitise (chlorine 100–200 ppm or hot water), final rinse; CIP is used for pipelines and tanks.

Personal hygiene: hand washing, clean protective clothing, head covering, no jewellery, medical screening and training of food handlers; illness reporting is mandatory.

Break-even quantity = fixed cost ÷ (selling price per unit − variable cost per unit); break-even sales = break-even quantity × selling price.

Project appraisal uses NPV (positive is viable), IRR (above the cost of capital), payback period, and benefit–cost ratio above 1.

MSME classification uses investment and turnover; PMFME and PMEGP provide subsidised loans, and FSSAI, GST, Udyam and factory licences are needed before food production.

Process equipment: pulper for fruit pulp, pulveriser for spices and grains, plate heat exchanger for pasteurisation, retort for canning, spray or freeze dryer, centrifuge, chiller.

Proximate analysis: moisture by oven at 105°C, ash in muffle furnace at 550°C, fat by Soxhlet, protein by Kjeldahl (N × 6.25), crude fibre, carbohydrate by difference.

Quality measurements: TSS by refractometer in °Brix, titratable acidity by titration with 0.1 N NaOH, pH by meter calibrated with pH 4 and pH 7 buffers.

Laboratory safety: autoclave at 121°C and 15 psi for 15 min, incubator at 37°C for bacterial plates, laminar flow for sterile work, and a fume hood for acids.