Dairy Chemistry

Step 1: Understanding the Concept:
The question asks about the application of a Butyro-refractometer in the context of dairy products. A refractometer is an instrument that measures the refractive index of a substance.
Step 2: Detailed Explanation:
Let's analyze the given uses:
A. Purity of ghee: Ghee (clarified butterfat) has a specific range for its refractive index. The Butyro-refractometer measures this value, known as the BR reading. If ghee is adulterated with other fats or oils (like vanaspati or vegetable oil), its refractive index will change. Thus, the instrument is a primary tool for checking the purity of ghee. This statement is correct.
B. B R reading of ghee: This is the direct measurement taken by the instrument. "BR reading" stands for Butyro-refractometer reading. This statement is inherently correct.
C. Fat content in milk: The fat content in milk is typically measured using methods like the Gerber method (centrifugation) or electronic milk analyzers, not a Butyro-refractometer. This statement is incorrect.
D. Vitamin content in milk: Vitamin content is measured using more sophisticated chemical analysis techniques like chromatography (HPLC), not by a refractometer. This statement is incorrect.
Therefore, the Butyro-refractometer is used to measure the BR reading of ghee, which in turn is used to determine its purity.
Step 3: Final Answer:
Statements A and B are correct. This corresponds to option (D).

Step 1: Understanding the Concept:
The question asks to identify the correct compositional and quality parameters for butter oil. Butter oil, also known as anhydrous milk fat (AMF), is a product made by removing almost all the water and non-fat solids from butter or cream, resulting in nearly pure milk fat.
Step 2: Detailed Explanation:
Let's analyze each parameter according to food standards (like FSSAI or Codex):
A. Butter fat - 99.5 to 99.8%: This is correct. The defining characteristic of butter oil/AMF is its extremely high fat content, typically mandated to be a minimum of 99.8%. The given range is representative of high-quality butter oil.
B. Moisture - 0.1 to 0.3%: This is correct. The removal of water is a key part of the manufacturing process. The legal maximum moisture content is very low, usually around 0.1% to 0.2%, so this range is acceptable.
C. Acidity (oleic) - 0.2 to 0.5%: This represents the free fatty acid (FFA) content, which is an indicator of hydrolytic rancidity. For good quality butter oil, the FFA content should be low, typically below 0.5%. This range is a standard quality specification.
D. Peroxide value - 0.0 to 0.1%: Peroxide value (PV) measures the initial stages of oxidative rancidity. For fresh, high-quality butter oil, the PV should be very low, ideally close to zero. The given range is indicative of a fresh product.
All four statements accurately describe the standard composition and quality specifications for butter oil.
Step 3: Final Answer:
Statements A, B, C, and D are all correct. Therefore, the correct option is (C).

Step 1: Understanding the Concept:
A "platform test" is a rapid test performed at the milk reception platform (dock) to quickly assess the quality of incoming raw milk and make a decision to accept or reject it. These tests must be fast and simple.
Step 2: Detailed Explanation:
Let's analyze the options:
(A) Sediment test: This is a rapid platform test where a standard volume of milk is filtered through a cotton disc to visually check for insoluble dirt and foreign matter.
(B) Turbidity test: This test is used to check the efficiency of sterilization in milk. It works on the principle that sterilization denatures whey proteins. If the sample is properly sterilized, adding a reagent will not cause turbidity. This is a laboratory test for processed milk, not a rapid platform test for raw milk.
(C) Alcohol test: This is a rapid platform test where an equal volume of alcohol (usually 68-72% ethanol) is mixed with milk. If the milk coagulates, it indicates high developed acidity or disturbed salt balance, meaning it will not withstand heat processing.
(D) Smell and colour: This is part of the organoleptic or sensory evaluation, the very first and most basic platform test performed by the milk grader.
Step 3: Final Answer:
The Turbidity test is a laboratory test for sterilized milk and is not a platform test for raw milk reception.

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.