Step 1: Understanding the Concept:
Ghee residue is the byproduct obtained after the clarification of ghee. It consists of charred or denatured milk proteins, water, and trapped fat. It has significant nutritional and industrial value.
Step 2: Detailed Explanation:
- Statement (A): Research has shown that the fat trapped in the residue (the lipids) tends to be higher in PUFAs compared to the bulk ghee. This is because phospholipids, which are concentrated in the residue, contain more unsaturated fatty acids. A value of $\approx$ 4.4% higher is a reported characteristic. Correct.
- Statement (B): RM (Reichert-Meissl) and Polenske values measure volatile fatty acids. These values are actually lower or similar in the residue compared to ghee. The residue fat doesn't preferentially trap these volatile acids. Incorrect.
- Statement (C): This is the most significant attribute of ghee residue. Phospholipids from the fat globule membrane are polar and bind to the denatured proteins, staying in the residue rather than dissolving into the non-polar ghee. Correct.
- Statement (D): The method (Direct Cream vs. Creamery Butter vs. Pre-stratification) determines how much protein is present and how long the heat is applied, which directly affects how many phospholipids are retained in the residue. Correct.
Therefore, A, C, and D are correct.
Step 3: Final Answer: (2) (A), (C) and (D) only.