Butter, ghee and cheese

In short

Butter, ghee and cheese are the three classical concentrated milk products: butter is an inverted (water-in-oil) fat emulsion (minimum 80% milk fat), ghee is almost anhydrous clarified milk fat (minimum 99.5% fat, not more than 0.5% moisture) and cheese is the protein-fat curd obtained by coagulating milk with rennet or acid and draining whey. India is the world's largest ghee market, and butter and cheese demand grows with QSR and bakery chains, so these unit operations dominate dairy plant operations. Examinations test composition standards under the FSS (Food Products Standards and Food Additives) Regulations, 2011, the process flow sheets, overrun and yield calculations, and defect diagnosis. Placement interviews at Amul (GCMMF/district unions), Mother Dairy, Britannia, Nestlé India, Schreiber Dynamix, Parag, Hatsun, Heritage and Dodla ask directly on churning control, ghee RM value and cheese make procedure.

Explained

Butter: definition, types and composition

• Butter (FSSR definition): a fatty product derived exclusively from milk or products obtained from milk, principally in the form of a water-in-oil emulsion. Legal standard: milk fat not less than 80% (table/creamery butter), moisture not more than 16%, common salt not more than 3% (salted), milk solids-not-fat not more than 1.5%; no added colouring except annatto/carotene, curcumin and beta-apo-8'-carotenal as permitted.
• Types: *creamery (table) butter* - made in a dairy from pasteurised cream; *desi/cooking butter* - from indigenous dahi cream (makkhan), not a standardised product for sale as table butter; *salted vs unsalted*; *sweet-cream vs ripened-cream (cultured) butter*; *continuous vs batch-churned*; *whey butter* from cheese whey cream.
• Structure: butter is an inverted emulsion - continuous fat phase (part liquid, part crystalline) enclosing dispersed moisture droplets, air and intact fat globules. Fine, uniformly dispersed moisture (droplets <10 µm) gives keeping quality; coarse free moisture invites microbial growth and "leaky" butter.
• Phase volume: of the 100 g, roughly 80-82 g fat, 15-16 g moisture, 0.5-1 g SNF, 0-2.5 g salt.

Butter manufacture - step by step

1. Cream receiving and grading: separate milk at 35-40 °C; cream for butter standardised to 33-40% fat (batch churn) or 40-45% (continuous, Fritz type). Judge flavour, acidity and neutralise high-acid cream with lime/NaOH to about 0.10-0.12% LA if needed.
2. Pasteurisation: high-temperature treatment, 90-95 °C for 15 s or 85-90 °C/15 s in a plate/tubular pasteuriser - destroys pathogens, inactivates lipase and peroxidase, removes volatile off-flavours (vacreation for weed taints).
3. Cooling and ageing (crystallisation): cool to 5-10 °C and hold 8-16 h so that enough fat crystallises; the classic Alnarp treatment (8-19-16 °C) manipulates hard/soft fat ratio with season. Insufficient ageing → greasy, leaky butter and high fat loss in buttermilk.
4. Ripening (optional): inoculate 1-2% starter (*Lc. lactis* subsp. *lactis*/*cremoris* for acid, *Lc. lactis* subsp. *lactis* biovar *diacetylactis* and *Leuconostoc* for diacetyl flavour) at 18-21 °C.
5. Churning: fill churn to about 1/3-1/2 capacity, churn at 20-35 rpm at 7-13 °C (winter higher, summer lower). Air-bubble/foam theory: globules concentrate at air interfaces, membranes rupture, liberated liquid fat cements globules into grains the size of wheat grains in 30-45 min.
6. Draining buttermilk and washing: drain buttermilk (fat loss should be ≤0.5-0.7%); wash grains 1-2 times with chilled potable water 1-2 °C below churning temperature to remove residual buttermilk solids.
7. Salting and working: add dry salt (1.5-2.5% on butter) or brine; work the butter to disperse moisture and salt, control final moisture and expel air. Over-working → greasy, dark butter; under-working → mottled, free moisture.
8. Packing and storage: pack in parchment/laminate or 500 g blocks and bulk 20 kg cartons; store at 5 °C for short term, −18 to −25 °C for months.
9. Continuous butter making (Fritz/Contimab type): cream enters a fast cylindrical churning cylinder with beater (1,400-3,000 rpm) → grains and buttermilk separate in the separating section → two-stage augered working section with vacuum and brine/moisture injection → continuous ribbon of butter. Capacity 500-10,000 kg/h, lower manpower, closer moisture control; Ammix/NIZO and Cherry-Burrell Gold'n'Flow are concentrate/re-combination processes.

Butter defects and quality control

• Flavour defects: rancid (lipolysis - raw-cream lipase or psychrotroph lipase), oxidised/metallic/tallowy (Cu, Fe contact, light), fishy (trimethylamine from lecithin in salted, high-acid butter), cheesy/putrid (proteolysis), flat (low diacetyl), feed/weed.
• Body and texture defects: greasy, sticky, crumbly/brittle (too much hard fat or over-cold working), sandy (undissolved salt), leaky (free moisture).
• Colour defects: mottled (uneven moisture/salt), streaky, surface discolouration/mould.
• Tests: moisture by oven/Kohman method or moisture balance, fat by Gerber/Mojonnier, salt by Mohr titration (AgNO₃), curd by difference; standard plate count, coliform, yeast and mould; peroxide value and Kreis test for oxidation. Butter is scored on a 100-point scale (flavour 45, body & texture 25, colour 15, salt 10, package 5 - weightings vary with the scoring card used).

Ghee: definition, methods and standards

• Ghee (FSSR): the pure clarified fat derived solely from milk, curd or desi butter or cream, to which no colouring matter or preservative is added. Moisture not more than 0.5%, milk fat not less than 99.5%; free fatty acid not more than 3.0% as oleic acid. Butyro-refractometer (BR) reading at 40 °C and Reichert-Meissl (RM) value limits are prescribed region-wise (e.g. Maharashtra/Gujarat RM ≥ 28, most other regions ≥ 28 with lower limits ≥ 23-24 for some hill/other states) - the exact state-wise table is in the regulation and is revised periodically, so quote it from the current FSSR Appendix rather than memory.
• Methods of manufacture:
  1. Desi (indigenous) method: whole milk → boil → cool → set to curd (dahi) with starter → churn curd → desi butter (makkhan) → clarify at 110-120 °C. Highest flavour, smallest scale, highest fat loss.
  2. Creamery butter method: the standard plant route - unsalted creamery/cooking butter is melted at 60-80 °C, fed to a steam-jacketed open ghee kettle, heated to 110-120 °C until moisture is driven off and the residue turns golden brown; settled 20-30 min; ghee siphoned, residue removed.
  3. Direct cream method: cream (50-60% fat) is heated directly in the kettle - continuous in large plants, saves butter-making, but flavour is milder and cream serum must be well removed.
  4. Pre-stratification method: melt butter at 80-85 °C, hold undisturbed 20-30 min so it forms three layers - top floating curd/denatured protein, middle fat, bottom buttermilk serum; remove top and bottom, clarify only the fat layer at 110-120 °C. Saves steam and time, gives low FFA, but slightly less of the typical cooked flavour.
  5. Continuous ghee making: cream/butter is pumped through a scraped-surface heat exchanger/vacuum flash chamber - uniform quality, high capacity.
• Flavour chemistry: the typical ghee flavour comes from free fatty acids, carbonyls (lactones, methyl ketones, aldehydes) and a trace of protein-degradation products produced at the clarification temperature; higher clarification temperature (120 °C+) → stronger flavour and better keeping quality (antioxidant phospholipids and SH-groups released from the residue) but risk of burnt flavour.
• Granulation: slow cooling with a seed of granular ghee gives the prized grainy texture; fast cooling gives a smooth/greasy body. Buffalo-milk ghee is whiter (no carotene; cow ghee is golden-yellow).
• Ghee residue: 5-8% of the butter weight, containing 35-55% fat and the bulk of the protein - used in sweets, chocolates, bakery fillings and animal feed; a real by-product value question in interviews.
• Adulteration and tests: Baudouin (furfural) test detects sesame oil - mandatory tracer in vanaspati, so a positive Baudouin indicates vanaspati/ til oil adulteration; Halphen test for cottonseed oil; BR reading, RM value, Polenske value, saponification value, iodine value for animal body fat/vegetable fat; opacity/phytosterol acetate test for vegetable fat. Agmark grading of ghee (AGMARK "Special/General" grades under the Agricultural Produce (Grading and Marking) Act, 1937) uses BR, RM, FFA and moisture.

Cheese: classification, make procedure and chemistry

• Cheese (FSSR): the ripened or unripened soft/semi-hard/hard product obtained by coagulating milk, skimmed milk, partly skimmed milk, cream, whey cream or buttermilk with rennet or other suitable coagulating agents and partially draining the whey.
• Classification:
  • By moisture/firmness: very hard (Parmesan, <35% moisture), hard (Cheddar, Edam), semi-hard (Gouda, blue), soft (Camembert, Mozzarella, paneer/cottage).
  • By ripening agent: bacterial-ripened interior (Cheddar, Swiss), surface mould (Camembert), interior mould (Roquefort/blue), surface smear (Limburger), unripened (paneer, cream cheese, mozzarella).
  • By coagulation: rennet-coagulated (Cheddar), acid-coagulated (cottage), acid+heat (paneer, ricotta), concentration/heat.
  • Processed cheese (FSSR): blend of one or more cheeses comminuted, melted with emulsifying salts (citrates, phosphates) at 70-85 °C - minimum milk fat 40% on dry basis and moisture not more than 47% for processed cheese (block); processed cheese spread has higher moisture and lower fat. Processed cheese keeps better, slices/melts uniformly and is the bulk of Indian retail cheese.
• Cheddar make procedure (the exam standard):
  1. Milk selection and standardisation to casein:fat about 0.68-0.70 (fat ≈ 3.2-3.5%), pasteurise 63 °C/30 min or 72 °C/15 s, cool to 31 °C.
  2. Starter addition: 1-2% mesophilic *Lc. lactis* subsp. *lactis*/*cremoris*; ripening 30-45 min to raise acidity by about 0.02-0.03% LA. Add CaCl₂ up to 200 mg/kg and annatto colour if used.
  3. Renneting: add standardised rennet (chymosin) 2-3 g/100 L; coagulum in 25-30 min. Chymosin cleaves κ-casein at Phe₁₀₅-Met₁₀₆, removing the glyco-macropeptide hair layer so para-casein micelles aggregate with Ca²⁺ bridges.
  4. Cutting with horizontal/vertical knives into 6-8 mm cubes; stand 5 min.
  5. Cooking/scalding: raise to 37-39 °C over 30 min with gentle stirring - expels whey (syneresis), controls moisture.
  6. Whey drainage at about 0.20-0.22% LA (pH ≈ 6.1-6.2); curd matted into slabs.
  7. Cheddaring: turn and pile slabs for 1.5-2 h at 36-38 °C until acidity 0.5-0.6% LA, pH about 5.2-5.3; the curd becomes fibrous (chicken-breast texture).
  8. Milling into 1.5-2 cm fingers; dry salting at 2-3% of curd weight in three applications.
  9. Hooping and pressing at 1.4-1.8 kg/cm² overnight; dressing/waxing or vacuum film packing.
  10. Ripening/curing at 4-10 °C and 85-90% RH: mild 2-3 months, medium 4-6 months, sharp 6-12 months. Residual chymosin, plasmin, starter and NSLAB enzymes hydrolyse casein → peptides and amino acids (flavour and smooth body); lipolysis gives FFA notes.
• Mozzarella/pizza cheese: thermophilic starter (*S. thermophilus* + *Lb. delbrueckii* subsp. *bulgaricus*), coagulate at 35-37 °C, cook to 41-45 °C, stretch (pasta filata) in hot water/brine at 70-80 °C → the parallel para-casein fibres give the stretch and melt; direct acidification with citric/acetic acid is used industrially.
• Paneer (the Indian benchmark): standardise milk to fat:SNF of about 1:1.65 (buffalo milk, 5.8-6% fat), heat to 82-90 °C/5 min, cool to 70 °C, coagulate with 1-2% citric acid solution to pH 5.3-5.4, drain through muslin, press 1-2 kg/cm² for 15-20 min, cube and chill in 4-6 °C water, pack. Yield about 18-21% from buffalo milk; buffalo milk gives firmer paneer than cow milk because of higher casein and calcium. Shelf life 6 days at refrigeration; FSSR permits the name "paneer" only for a milk-fat product - the vegetable-fat analogue must be labelled an analogue.
• Cheese defects: bitter (excess rennet, proteolytic starter), sour/acid (over-acid development), rancid, fruity/fermented; gassy/open texture and blowing (coliforms early, *Clostridium tyrobutyricum* late blowing), mouldy rind, pink discolouration, mealy/corky body. Control = good-quality milk, correct starter activity, hygiene, salt and temperature control.

Standards, regulators and plant practice

• Food Safety and Standards Act, 2006 with the FSS (Food Products Standards and Food Additives) Regulations, 2011 - compositional standards for butter, ghee, cheese, processed cheese and paneer; FSS (Licensing and Registration) Regulations, 2011 for plant licence; FSS (Packaging) and (Labelling and Display) Regulations, 2018/2020 for pack declarations.
• FSSAI Schedule 4 Part III (hygiene for milk and milk products) governs dairy GMP/GHP; Hazard Analysis and Critical Control Point (ISO 22000 / FSSC 22000) systems are standard in export plants. CCPs: pasteurisation, metal detection, foreign matter, moisture in butter, pH/acidity in cheese.
• BIS: specifications exist for butter, ghee and hard cheese, and IS 1479/IS 1224 series methods for chemical analysis of milk and milk products; several older IS numbers have been revised or withdrawn, so verify the current number and year before quoting it in a specification.
• Other applicable instruments: Agmark grading for ghee and butter, Legal Metrology (Packaged Commodities) Rules, 2011 for net quantity, Milk and Milk Product Order (MMPO) functions now subsumed under FSSAI, and the four Labour Codes in force from 21 November 2025 which replaced the Factories Act for plant safety, hours and welfare obligations. GST under the 5%/18%/40% structure effective 22 September 2025: butter, ghee and cheese moved from 12% to 5%, and pre-packaged, labelled paneer to nil - check the current rate notification before invoicing.

Key points

• Butter standard - not less than 80% milk fat, not more than 16% moisture, not more than 3% salt, not more than 1.5% MSNF.
• Inverted emulsion - butter is water-in-oil; fine moisture dispersion (<10 µm) is the key to keeping quality.
• Cream for churning - 33-40% fat batch, 40-45% continuous; higher fat cream churns faster with less buttermilk fat loss.
• Ageing/crystallisation - 5-10 °C for 8-16 h; Alnarp treatment adjusts the solid-fat ratio seasonally.
• Churning temperature - 7-13 °C; too high gives greasy butter and high fat loss, too low gives slow churning and crumbly body.
• Overrun in butter is small and legally bounded (moisture + salt added to fat), unlike ice cream's air overrun.
• Ghee standard - not less than 99.5% milk fat, not more than 0.5% moisture, FFA not more than 3.0% as oleic acid.
• Clarification temperature - 110-120 °C; raising it strengthens flavour and keeping quality but risks a burnt note.
• Pre-stratification - three-layer separation at 80-85 °C before clarification; saves energy, lowers FFA.
• RM value - Reichert-Meissl value measures water-soluble volatile fatty acids (mainly butyric); high RM is characteristic of milk fat, low RM signals vegetable-fat adulteration.
• Baudouin test - positive means sesame oil, hence vanaspati, in ghee; Halphen indicates cottonseed oil.
• Ghee residue - 5-8% of butter weight, 35-55% fat; a saleable by-product, not waste.
• Rennet action - chymosin splits κ-casein at Phe₁₀₅-Met₁₀₆; para-casein aggregates with calcium bridges.
• Cheddaring and milling - slab piling to pH 5.2-5.3 and salting at 2-3% of curd define Cheddar's fibrous body.
• Pasta filata - hot stretching aligns para-casein fibres, giving mozzarella its stretch and melt.
• Paneer - acid+heat coagulation at pH 5.3-5.4 after 82-90 °C/5 min heating; yield about 18-21% from buffalo milk.
• Processed cheese - emulsifying salts (citrates/phosphates) peptise casein so fat does not leak on melting; block type minimum 40% fat on dry basis.
• Cheese yield depends on casein and fat retention - the Van Slyke formula is the examined calculation.

Formulas and examples

Example 1 - Butter yield and overrun. 1,000 kg of cream at 40% fat is churned. Buttermilk obtained = 180 kg testing 0.5% fat. Butter has 80.5% fat.

• Fat in cream = 1,000 × 0.40 = 400 kg.
• Fat lost in buttermilk = 180 × 0.005 = 0.9 kg.
• Fat in butter = 400 − 0.9 = 399.1 kg.
• Butter weight = 399.1 / 0.805 = 495.8 kg.
• Overrun = (495.8 − 400)/400 × 100 = 23.95%.
• Fat loss = 0.9/400 × 100 = 0.225% of fat - well within the 0.5-0.7% norm.

Example 2 - Ghee yield from butter. 500 kg of unsalted white butter testing 82% fat is clarified; ghee contains 99.5% fat; fat lost in ghee residue is 2.5% of the fat in butter.

• Fat in butter = 500 × 0.82 = 410 kg.
• Fat lost in residue = 410 × 0.025 = 10.25 kg → fat available = 399.75 kg.
• Ghee obtained = 399.75 / 0.995 = 401.76 kg.
• Yield on butter = 401.76/500 × 100 = 80.35%.
• If the plant sells residue at ₹120/kg and gets 35 kg of residue, by-product realisation = ₹4,200 per batch.

Example 3 - Van Slyke cheese yield. Milk with 3.6% fat and 2.5% casein; Cheddar moisture 37%.

• 0.93 F = 0.93 × 3.6 = 3.348; add C = 2.5 → 5.848; subtract 0.1 → 5.748.
• × 1.09 = 6.265; ÷ (1 − 0.37) = 6.265/0.63 = 9.94 kg cheese per 100 kg milk.
• So 10,000 L (≈10,300 kg) of such milk yields about 1,024 kg of Cheddar, and about 9,000 kg of whey for processing.

Example 4 - Cream standardisation for butter (Pearson square). A dairy has 2,000 kg cream at 48% fat and must bring it to 40% for churning, using skim milk at 0.1% fat.

• Let x kg skim milk be added: (2,000 × 48 + x × 0.1) = (2,000 + x) × 40.
• 96,000 + 0.1x = 80,000 + 40x → 16,000 = 39.9x → x = 401.0 kg skim milk.
• Final cream = 2,401 kg at 40% fat (fat = 960.1 kg ≈ 2,401 × 0.40 ✓).

Example 5 - Acidity and neutralisation check. 10 mL cream (density ≈ 1.0) needs 1.8 mL of 0.1 N NaOH to the phenolphthalein end point.

• % LA = (1.8 × 0.009 × 100)/10 = 0.162% - too acid for churning sweet-cream butter, so neutralise to about 0.11% LA before pasteurisation.

Where it is used

• Cooperative and private dairy plants: Amul/GCMMF and district unions, Mother Dairy, Nandini (KMF), Aavin, Verka, Saras, Hatsun, Heritage, Dodla - butter, ghee and cheese lines with continuous butter makers and ghee kettles/continuous clarifiers.
• Cheese and processed-cheese manufacture: Amul, Britannia, Go (Gowardhan/Parag), Schreiber Dynamix (supplies pizza chains), Flanders/ACMA - mozzarella and processed cheese for Domino's, Pizza Hut and QSR chains.
• Job roles: production/shift officer (butter-ghee section), QA/QC chemist (moisture, fat, FFA, RM value, BR reading, Baudouin test), R&D product developer, FSSAI-recognised food analyst, procurement and milk-field officer, plant maintenance for churns, CIP and SSHEs.
• Regulatory and testing laboratories: FSSAI NABL-accredited labs and state food testing labs for ghee adulteration surveillance; Agmark grading laboratories.
• Sweets, bakery and HORECA supply: ghee for mithai and ghee-based sweets, butter for bakery and table use, ghee residue into chocolate and burfi; paneer for institutional catering and retail packs.
• Export and by-products: AMF/butter oil and ghee exports to West Asia and the Indian diaspora (APEDA facilitated), whey powder and WPC plants added to cheese units.

Interview questions

• Q: Why is butter called an inverted emulsion? A: Milk and cream are oil-in-water emulsions; in butter the phases invert, so fat becomes the continuous phase with water droplets dispersed in it.
• Q: What happens if cream is churned without proper ageing? A: Too little fat is crystallised, so grains do not form cleanly - churning is slow, fat loss in buttermilk rises and the butter is greasy and leaky.
• Q: Why is butter washed after draining buttermilk? A: To remove residual buttermilk solids (lactose, protein) that feed spoilage organisms, and to adjust grain temperature and firmness before working.
• Q: Why is cream for butter pasteurised at a higher temperature than milk? A: Fat protects microbes, so 90-95 °C/15 s is used to destroy pathogens, inactivate lipase and peroxidase and strip volatile off-flavours.
• Q: What gives ghee its characteristic flavour? A: Free fatty acids, carbonyls (lactones, methyl ketones, aldehydes) and protein-degradation products generated at 110-120 °C during clarification.
• Q: What is the advantage of the pre-stratification method? A: Removing the curd and serum layers before clarification saves steam and time and gives ghee with lower FFA and better keeping quality.
• Q: How would you detect vanaspati in ghee? A: The Baudouin test detects sesame oil, which is a statutory tracer in vanaspati; a positive colour reaction, with a low RM value and abnormal BR reading, confirms adulteration.
• Q: Why is buffalo-milk ghee white while cow ghee is yellow? A: Buffaloes convert carotene to colourless vitamin A, so buffalo milk fat has essentially no carotene pigment.
• Q: Where does chymosin act on casein? A: It hydrolyses κ-casein at the Phe₁₀₅-Met₁₀₆ bond, removing the hydrophilic glyco-macropeptide so para-casein micelles aggregate in the presence of calcium.
• Q: What is cheddaring and why is it done? A: Piling and turning matted curd slabs at 36-38 °C until pH falls to about 5.2-5.3; it develops acidity, expels whey and gives the characteristic fibrous texture.
• Q: Why do emulsifying salts work in processed cheese? A: Citrates and phosphates sequester calcium and peptise casein into an effective emulsifier, so fat stays emulsified and the product melts smoothly instead of oiling off.
• Q: Why does buffalo milk give firmer paneer than cow milk? A: Higher casein and calcium content produces a denser, more cohesive coagulum with better yield and a firmer body.
• Q: What causes late blowing in cheese? A: *Clostridium tyrobutyricum* spores from silage-fed milk ferment lactate to butyric acid, CO₂ and H₂ during ripening, cracking the block.

Common mistakes

• Treating butter overrun like ice-cream overrun - butter has no air incorporation worth counting; the gain is moisture, salt and curd.
• Ignoring the fat lost in buttermilk or ghee residue in yield calculations, which overstates yield.
• Quoting ghee moisture as "not more than 0.5%" but then claiming fat is "100%" - the standard is milk fat not less than 99.5%.
• Using a single RM value limit for all of India; the FSSR prescribes region-wise RM and BR limits, which are revised from time to time.
• Confusing acid-coagulated paneer with rennet-coagulated cheese, or calling a vegetable-fat analogue "paneer" or "cheese" - prohibited by FSSR labelling rules.
• Omitting the moisture term in the Van Slyke formula, or using casein as total protein - casein is about 78-80% of milk protein.
• Reporting a pasteurisation temperature for cheese milk without noting that over-pasteurisation denatures whey protein, slows renneting and gives a weak, moisture-retaining curd.
• Mixing up Polenske and Reichert-Meissl values (water-insoluble vs water-soluble volatile fatty acids).

Related topics

Fermented milk products · Ice cream and frozen desserts · Milk chemistry and composition · Cream separation and standardisation · Dairy plant sanitation and FSSAI food safety management · Condensed and dried milk products