Milk Adulteration Detection & FSSAI Standards | Auriga

Milk adulteration is one of India’s most persistent food safety challenges. With the dairy sector being a Rs 11 lakh crore industry and milk being a daily staple for hundreds of millions of Indians — particularly children and the elderly — adulteration poses serious public health risks that go far beyond economic fraud.

FSSAI’s national milk quality surveys have consistently found alarming rates of adulteration across Indian states. A 2011 FSSAI study found that 68.4% of milk samples tested across India were non-conforming — primarily due to dilution and addition of substances that compromise quality, safety, or both.

This blog post explores the technical dimensions of milk adulteration: what adulterants are added, how they are detected, and what FSSAI standards govern milk quality in India. For an accessible consumer-focused guide to checking milk adulteration at home, see our companion page how to check milk adulteration.

Why Milk Is a Target for Adulteration

Milk’s high value per liter, liquid nature, and complex composition make it a particularly vulnerable commodity:

• High-value commodity: Premium milk products command significant price premiums — creating incentives to substitute or dilute
• Short shelf life: Rapid turnover limits the time window for authorities to test and act on adulterated product
• Complex composition: Natural variability in milk composition (fat, protein, lactose, SNF) can mask the addition of certain adulterants
• Long supply chain: Milk moves from farm to collection center to processing plant to retailer, with multiple handoff points where adulteration can occur
• Testing historically limited: While FSSAI has scaled up surveillance, testing capacity relative to the volume of milk in the market remains a challenge

Common Milk Adulterants and Their Health Risks

Water

The most common adulterant — diluting milk with water reduces costs for the seller while increasing apparent volume. Health risk is low directly, but water addition:

• Reduces nutritional value (protein, fat, vitamins, minerals per serving)
• May introduce microbiological contamination if non-potable water is used (particularly serious in rural areas)
• Reduces economic value for consumers paying for nutrients they are not receiving

Detection: Lactometer (milk hydrometer) measures specific gravity. Pure milk has specific gravity 1.028-1.032. Added water reduces specific gravity. Simple, rapid, but imprecise.

Modern method: Cryoscopy (freezing point depression). Pure cow milk has a freezing point of -0.512 to -0.550 degrees C. Water addition raises the freezing point toward 0 degrees C. Cryoscopy is the most accurate and sensitive method for water detection, detecting as little as 2-3% added water. BIS and ISO reference methods for milk authenticity use cryoscopy.

Detergent and Soap

Detergent is added to stabilize emulsions (making adulterated or diluted milk appear creamier) and to neutralize acidity in spoiling milk. Detergents are toxic at relevant concentrations — causing digestive irritation, liver and kidney damage with chronic exposure.

Detection:

• Methylene blue reduction test (MBRT) / Resazurin test: Detergents interfere with dye reduction by bacteria — positive result indicates detergent presence
• Surface foam test: Detergent produces persistent foam when milk is shaken; fresh pure milk produces foam that quickly dissipates
• Chemical test: Bromocresol purple indicator in milk — detergent changes color from yellow to purple/violet
• Quantitative method: HPLC or spectrophotometric methods for quantification of specific detergent classes

Urea

Added to increase apparent protein content (since urea contains nitrogen, which standard protein tests measure as total nitrogen). Also used to neutralize acidity and preserve milk that is beginning to spoil. Urea is non-toxic at low levels but its use is deliberate fraud to misrepresent protein content.

Detection:

• Urease test (qualitative): Urease enzyme converts urea to ammonia; Nessler’s reagent detects ammonia — yellow-brown color indicates urea
• p-Dimethylaminobenzaldehyde (DMAB) test: DMAB reacts with urea to produce a yellow color
• Quantitative: Diacetyl monoxime method for accurate urea quantification at mg/L levels

Natural milk contains a small amount of urea (up to 30 mg/100 mL) — detection methods must distinguish added urea from naturally occurring levels.

Starch and Cereal Adulterants

Starch, flour, and other cereal starches are added to increase apparent total solids (SNF — solids not fat). They increase viscosity and appear to improve quality on simple density tests.

Detection:

• Iodine test: Classic, simple, and reliable. Iodine solution produces blue-black color in the presence of starch. Pure milk shows yellow-brown color with iodine. Blue-black indicates starch addition.
• Microscopic examination: Starch granules are visible under microscope
• Enzymatic method: Glucoamylase digestion followed by glucose measurement for quantification

Glucose and Sugar

Sucrose, glucose, or other sugars are added to increase SNF readings on basic tests without using more expensive milk solids.

Detection:

• Barfoed’s test (for glucose/reducing sugars): Glucose reduces copper sulfate in Barfoed’s reagent — positive result (red precipitate) indicates added reducing sugars
• Lactase-glucose test: Lactose is the primary natural sugar in milk. Added glucose is detected by enzymatic assay
• HPLC: Definitive quantification of glucose, sucrose, lactose, and other sugars in a single chromatographic run

Formalin (Formaldehyde)

Formaldehyde preserves milk by inhibiting bacterial growth — allowing adulterated or low-quality milk to appear fresh for longer. Formalin is a probable human carcinogen and is highly toxic. There is no acceptable level of formaldehyde addition to milk.

Detection:

• Hehner’s test: Formalin in milk, when treated with concentrated sulphuric acid carefully, produces a violet ring at the junction
• Phenylhydrazine hydrochloride test: Yellow crystalline precipitate in formalin-adulterated milk
• Colorimetric assay: Chromotropic acid reacts with formaldehyde to produce a distinctive purple color
• Quantitative GC-MS: Definitive method for formaldehyde quantification at mg/L levels

Hydrogen Peroxide

Added as a preservative in spoiling milk. Hydrogen peroxide is an oxidizing agent that kills bacteria but also destroys vitamins (particularly vitamin C and some B vitamins) and degrades milk proteins.

Detection:

• Peroxidase test: Raw milk naturally contains peroxidase enzyme. Added H2O2 converts normally peroxidase-negative (pasteurized) milk to an apparent peroxidase positive
• Vanadium pentoxide test: V2O5 in H2SO4 — pink color indicates H2O2 presence
• Titanium sulfate test: Titanium sulfate produces yellow color with H2O2

Neutralizers (Sodium Carbonate, Sodium Bicarbonate)

Added to neutralize acid in souring milk — masking natural acidity that would indicate spoilage and extending apparent shelf life of low-quality milk.

Detection:

• Titratable acidity test: Abnormally low acidity (below 0.15% as lactic acid) indicates neutralizer addition
• pH measurement: Pure milk pH is 6.4-6.8. Neutralizer raises pH above 7.0
• Rosalic acid test: Sodium carbonate turns milk pink with rosalic acid indicator
• Quantitative: Turbidity test after addition of alcohol — neutralizers change precipitation pattern

Melamine

The most notorious modern adulterant — melamine was added to milk powder in the 2008 China melamine scandal, causing kidney failure and deaths in thousands of infants. Melamine is a nitrogen-rich compound that artificially increases apparent protein content in routine Kjeldahl protein analysis.

FSSAI standards set zero tolerance for melamine in liquid milk and a maximum limit of 1 ppm in solid food products (formula excluded). For infant formula, the limit is 1 mg/kg (1 ppm).

Detection:

• ELISA (Enzyme-Linked Immunosorbent Assay): Immunological screening method — sensitive and specific for melamine; suitable for large-scale screening
• LC-MS/MS: Definitive quantification at the ppb level. Required for confirmation of positive ELISA results and for regulatory compliance testing
• GC-MS: Alternative confirmatory method

Auriga’s HPLC and LC-MS/MS platforms support melamine testing at FSSAI-required sensitivity levels as part of our food testing capabilities.

FSSAI Standards for Milk Quality

FSSAI’s Food Safety and Standards (Food Products Standards and Food Additives) Regulations 2011 set compositional standards for milk by species:

Cow Milk

Parameter	Minimum Standard
Fat content	Min 3.5%
Total Solids (TS)	Min 8.5% (Solids Not Fat)
Protein (Nx6.38)	Min 3.0% (approx.)

Buffalo Milk

Parameter	Minimum Standard
Fat content	Min 5.0%
Solids Not Fat (SNF)	Min 9.0%

Toned Milk

Parameter	Minimum Standard
Fat content	Min 3.0%
Solids Not Fat (SNF)	Min 8.5%

Double Toned Milk

Parameter	Minimum Standard
Fat content	Min 1.5%
Solids Not Fat (SNF)	Min 9.0%

Microbiological Standards (Pasteurized Milk)

Parameter	Limit
Total Plate Count	Max 30,000 CFU/mL
Coliform Count	Max 10 MPN/mL
E. coli	Absent
Salmonella	Absent in 25 mL
Listeria monocytogenes	Absent in 25 mL

Veterinary Drug Residues

FSSAI sets maximum residue limits (MRLs) for veterinary drugs (antibiotics, hormones) in milk. Key limits:

• Antibiotics (penicillin, tetracyclines, sulphonamides): FSSAI adopts Codex Alimentarius MRLs for most
• Aflatoxin M1 (mycotoxin): Maximum 0.5 ppb (0.5 microgram/kg) in liquid milk
• Pesticide residues: Various compounds with limits per FSSAI contaminant regulations

Modern Laboratory Testing Approach

A comprehensive dairy testing panel at Auriga for regulatory compliance includes:

Compositional analysis: Fat (Gerber or Rose-Gottlieb method / AOAC methods), protein (Kjeldahl or Dumas), total solids (gravimetric), SNF (calculated), lactose, moisture.

Adulteration screen: Freezing point (cryoscopy), specific gravity, acidity, pH, neutralizers, starch, glucose/sucrose, urea, formalin, hydrogen peroxide, detergent.

Contaminants: Aflatoxin M1 (ELISA screening, HPLC confirmation), melamine (LC-MS/MS), veterinary drug residues (multi-class LC-MS/MS), pesticide residues, heavy metals.

Microbiological: Total plate count, coliforms, E. coli, Salmonella, Listeria, Staphylococcus aureus, Brucella (for certain regulatory purposes).

Visit our food testing page to learn more about our dairy testing capabilities, or request a quote for a customized testing package aligned with your FSSAI compliance requirements.

Conclusion

Milk adulteration is a scientifically tractable problem — for every adulterant added, there is an analytical method capable of detecting and quantifying it. The challenge is systematic, regular testing across the supply chain: at farm collection points, processing facilities, and final product stage.

FSSAI’s expanding surveillance programs and the increasing capability of accredited private laboratories mean that adulteration is both more detectable and more consequential than ever. For dairy processors, retailers, and brands, proactive testing is both a regulatory requirement and a consumer trust investment. For the industry as a whole, consistent enforcement of FSSAI standards is the path to a safer, more transparent dairy sector.