The quality and authenticity of ghee are commonly assessed using the Reichert-Meissel (R.M.) value and Polenske value (P.V.), which are important physicochemical constants of milk fat. These parameters are based on the unique fatty acid composition of milk fat and are widely used for detecting adulteration and evaluating the purity of ghee. Unlike most vegetable oils and animal fats, milk fat contains significant quantities of short-chain volatile fatty acids that contribute to its characteristic flavour and aroma.

The Reichert-Meissel (R.M.) value is defined as the number of millilitres of 0.1 N aqueous alkali required to neutralize the water-soluble volatile fatty acids obtained from 5 g of ghee. It primarily reflects the concentration of lower fatty acids such as butyric (C4:0) and caproic (C6:0) acids. Since these fatty acids are present in relatively high amounts in milk fat and only in negligible quantities in most other fats and oils, the R.M. value serves as an important indicator of the genuineness of ghee. A decrease in the R.M. value may indicate adulteration with non-milk fats or vegetable oils.

The Polenske value (P.V.) is defined as the number of millilitres of 0.1 N aqueous alkali required to neutralize the water-insoluble volatile fatty acids obtained from 5 g of ghee. It is associated mainly with fatty acids such as caprylic (C8:0) and capric (C10:0), which are volatile but only sparingly soluble in water. The Polenske value complements the R.M. value and provides additional information regarding the composition and origin of milk fat. Generally, cow ghee exhibits a higher Polenske value (2–3) than buffalo ghee (1–1.5), whereas the R.M. value of pure ghee is typically around 28 or higher.

Together, the R.M. and Polenske values provide a characteristic fingerprint of milk fat and are extensively used in dairy quality control laboratories for assessing the purity, authenticity, and quality of ghee. These constants are particularly valuable for identifying adulteration, as substitution with vegetable oils or other animal fats significantly alters the proportion of volatile fatty acids and consequently affects both R.M. and Polenske values.