Methods for Analyzing Ghee Quality

Ghee is one of the most valued dairy products in India and across South Asia, used in cooking, religious practices, and traditional medicine for centuries. But with premium pricing and high consumer demand, ghee is also one of the most frequently adulterated food products in the market. Ensuring that a batch of ghee is pure, fresh, and of acceptable quality requires more than sensory observation – it demands standardized laboratory testing. Four key tests form the backbone of ghee quality analysis: moisture content determination, free fatty acid (FFA) measurement, butyro refractometer (BR) reading, and the Reichert-Meissl (RM) value. Each test evaluates a different aspect of ghee quality, and together they provide a comprehensive picture of whether a product meets regulatory and consumer standards.

Why ghee testing matters 🔗

Ghee quality testing is not optional for commercial producers – in India, it is governed by FSSAI (Food Safety and Standards Authority of India), which has defined specific physico-chemical limits for moisture, free fatty acids, BR reading, and RM value. Products graded under the Agmark system must meet even stricter tolerances. These standards exist to protect consumers from adulterated or spoiled ghee and to maintain fair trade practices. Testing is also important because the natural composition of ghee can vary depending on the milk source (cow, buffalo, or mixed), the season, and the region – making standardized test parameters essential reference points for quality assurance.

Moisture content determination 🔗

Moisture is the first and most fundamental parameter tested in ghee. Although ghee is a nearly anhydrous fat, even trace amounts of water can significantly affect its shelf life and safety. FSSAI regulations permit a maximum of 0.5% moisture in commercial ghee, while Agmark Special grade allows only up to 0.3%.

How the test is performed 🔗

Moisture content in ghee is measured as the loss in mass when a sample is heated in a hot air oven at 105 ± 1°C until it reaches a constant weight. A pre-weighed sample of ghee – typically 5 to 10 grams – is placed in a flat-bottomed dish and dried at this controlled temperature. The difference in weight before and after drying, expressed as a percentage of the original sample weight, gives the moisture content. The calculation is straightforward:

% Moisture = [(Weight before drying – Weight after drying) / Weight before drying] × 100

Accurate weighing both before and after drying is critical. The sample must cool in a desiccator before the final weighing to prevent it from absorbing atmospheric moisture, which would skew the result. Consistent oven performance – particularly temperature uniformity – is one of the most important factors in obtaining reliable and reproducible moisture readings.

Why moisture control is critical 🔗

Water in ghee creates conditions for microbial growth and promotes hydrolytic rancidity – the breakdown of fat molecules due to the reaction between water and triglycerides. Research from the Journal of Dairy Science has shown that ghee with added water deteriorates significantly faster, with a sharp rise in acid value (a measure of FFA) during storage. Keeping moisture within the prescribed limit is therefore directly linked to shelf life, safety, and flavor stability.

Free fatty acid (FFA) content 🔗

Free fatty acids are the direct products of fat breakdown. When ghee deteriorates – due to heat, moisture, microbial activity, or poor handling – its triglycerides break down and release individual fatty acids. These liberated acids are what cause the characteristic rancid smell and sharp, unpleasant taste associated with spoiled ghee. Measuring FFA content is therefore a direct indicator of freshness and quality.

Titration procedure 🔗

The standard method for FFA determination involves titration with 0.1N sodium hydroxide (NaOH). About 30 grams of melted ghee is dissolved in 50 ml of 95% ethyl alcohol. The mixture is then titrated against 0.1N NaOH using phenolphthalein as an indicator. The endpoint is reached when a faint pink color persists, indicating complete neutralization of the free acids. The FFA content is expressed as a percentage of oleic acid using the formula:

% FFA (as oleic acid) = Volume of 0.1N NaOH used × 2.82 / Weight of sample

The Agmark grading system classifies ghee into three grades based on FFA levels: Special grade (max 1.4%), General grade (max 2.5%), and Standard grade (max 3.0%). FSSAI’s general standard caps FFA at 3.0%. Higher values indicate poor raw material quality, inadequate processing, or deterioration during storage.

Butyro refractometer (BR) reading 🔗

The butyro refractometer (BR) reading measures the refractive index of ghee – essentially, how much light bends when it passes through the melted fat. Because different fats and oils have distinct refractive indices, this test is a quick and reliable frontline tool for detecting adulteration.

Procedure and interpretation 🔗

The test is conducted at a controlled temperature of 40°C. The prisms of the butyro refractometer are first cleaned with petroleum ether and allowed to dry. Water circulation through the instrument maintains the prism temperature at 40°C. A small drop of clarified (melted) ghee is placed between the prisms, and after allowing two minutes for the sample to equilibrate, the scale reading is noted through the eyepiece.

The BR reading is temperature-sensitive – a correction factor of 0.55 is added for each degree above 40°C or subtracted for each degree below 40°C to standardize the reading. According to FSSAI standards, the acceptable BR reading for standard ghee ranges between 40.0 and 44.0. A reading outside this range raises a flag for possible adulteration.

Most vegetable oils have a higher refractive index than pure milk fat. When vegetable oil is mixed into ghee, it pushes the BR reading above 44.0. The BR test can detect adulteration with a range of cheaper fats and oils, though it has limitations – coconut oil and palm oil, which have properties closer to milk fat, may not be reliably detected through BR reading alone. Modern digital butyro refractometers offer automatic temperature compensation, eliminating manual correction calculations and delivering faster, more consistent results.

Reichert-Meissl (RM) value 🔗

Of all the standard ghee tests, the Reichert-Meissl (RM) value is the most specific indicator of ghee authenticity. It measures the quantity of water-soluble volatile fatty acids present in the fat – primarily butyric acid (C4:0) and caproic acid (C6:0) – which are unique to milk fat and rarely found in vegetable or other animal fats. This makes the RM value a chemical “fingerprint” for genuine ghee.

How RM value is determined 🔗

The procedure begins with saponification – a 5-gram sample of ghee is treated with an alkaline solution (potassium hydroxide in glycerol) to convert the triglycerides into soap and release the fatty acids. The mixture is then acidified and subjected to steam distillation, which separates out the volatile water-soluble fatty acids. The distillate is collected and titrated against a standard alkali solution. The RM value is expressed as the number of milliliters of 0.1N alkali needed to neutralize the volatile fatty acids distilled from 5 grams of fat, with butyric acid accounting for roughly 75% of the RM value and caproic acid contributing about 25%.

Standard ranges and adulteration detection 🔗

As per current FSSAI standards, the minimum acceptable RM value for ghee is 24, applicable uniformly across India. For Agmark-graded ghee, the RM value must be at least 28. A low RM value is a strong indicator that non-dairy fats – such as vegetable oils or animal body fats – have been mixed in, as these fats contain little to no short-chain volatile fatty acids. The Consumer Affairs Ministry’s comparative study on commercial ghee brands confirmed that RM value is among the most reliable discriminators between pure and adulterated ghee.

It is worth noting that ghee produced in cotton tract areas – regions where cattlefeed includes cottonseed – naturally yields a lower RM value (minimum 21), because cottonseed feeding alters the short-chain fatty acid profile of milk fat. This regional variation has been recognized in regulatory standards, though recent FSSAI amendments have moved toward a uniform minimum of 24 nationwide.

Sample handling and the importance of accurate testing 🔗

All four tests depend heavily on how the sample is collected and prepared. Ghee separates into different layers on standing, so samples must be melted and thoroughly mixed before testing to ensure they are representative. Contamination of glassware, incorrect weighing, or temperature deviations during BR measurement can all introduce significant errors. Standardized procedures – such as those published in IS 3508 by the Bureau of Indian Standards – exist precisely to minimize these variables and ensure that results are comparable, legally defensible, and reliable across laboratories.

Modern laboratories increasingly complement these classical methods with advanced techniques like Gas Chromatography-Mass Spectrometry (GC-MS) and RP-HPLC, which can detect sophisticated forms of adulteration that the traditional tests may miss. Nevertheless, moisture determination, FFA titration, BR reading, and RM value remain the legally accepted, cost-effective, and practically robust standards for routine ghee quality assurance.

Bringing it all together 🔗

Each of these four tests targets a distinct quality dimension. Moisture content tells you about shelf life and safety. FFA levels reveal the freshness and integrity of the fat. The BR reading offers a quick purity check by measuring how light travels through the ghee. And the RM value confirms that what’s in the container is genuinely milk-fat derived ghee and not a blend with cheaper substitutes. Together, they form a systematic, evidence-based approach to quality assurance – one that protects consumers, supports fair market practices, and helps manufacturers maintain standards that generations of ghee users have come to expect.

What do you think? Given that adulteration is still widely reported in commercial ghee, do you believe current testing standards and enforcement are sufficient to protect consumers? And if you were a ghee producer, which of these four tests would you prioritize first in your quality control workflow – and why?

References

1. https://www.fssai.gov.in/
2. https://wdra.gov.in/web/wdra/ghee
3. https://www.academia.edu/25614403/Determination_of_Moisture_in_Ghee
4. https://adpi.org/methodsofanalysis/analytical-method-003-determination-of-moisture/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7774801/
6. https://safemilklabs.com/what-is-butyro-refractometer-br-reading-in-ghee/
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC9579228/
8. https://aurigaresearch.com/purity-of-ghee-accuracy-test-by-butyro-refractometer-br-meter/
9. https://consumeraffairs.gov.in/public/upload/admin/cmsfiles/consumer_products/Ghee_consumer_products.pdf
10. https://law.resource.org/pub/in/bis/S06/is.3508.1966.pdf