Question

The RM value of ghee generally varies between

• A. 20-25
• B. 28-32
• C. 13-18
• D. 9-12

Hint:

Memorize the two most important chemical constants for ghee purity: {RM Value:} Minimum 28. Measures short-chain fatty acids. {BR Reading:} 40-44 at 40°C. Measures refractive index. These are very common questions for quality control.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The RM value, or Reichert-Meissl value, is a chemical constant used to assess the purity of butterfat (ghee). It specifically measures the quantity of volatile, water-soluble short-chain fatty acids (like butyric acid), which are uniquely abundant in milk fat compared to other fats and oils.
Step 2: Detailed Explanation:
A high RM value is a characteristic signature of pure ghee. Adulteration with vegetable oils, vanaspati, or animal body fats, which lack these short-chain fatty acids, will drastically lower the RM value.
Food laws (like FSSAI in India) set a minimum legal limit for the RM value of ghee to prevent adulteration.
Let's analyze the options:
(A) 20-25: This is below the legal minimum for most types of ghee and indicates probable adulteration.
(B) 28-32: This is the classic and expected range for pure ghee from cows or buffaloes. The legal minimum is generally 28 (or 26 in some areas).
(C) 13-18 & (D) 9-12: These values are extremely low and would indicate gross adulteration.
Step 3: Final Answer:
The normal RM value for pure ghee varies between 28 and 32.