ICAR AIEEA PG Dairy Science 14 July 2023 Shift-1 Paper

Regulatory evaluations under FSSAI regulations:

• Statement (I) is true: Under FSS (Advertising and Claims) Regulations, 2018, skim milk (containing not more than $0.5\%$ fat) qualifies for nutritional claims including 'fat-free' (maximum $0.5\text{ g}$ fat per $100\text{ ml}$), 'cholesterol-free', and 'low in saturated fat'.
• Statement (II) is false: Under the previous Prevention of Food Adulteration (PFA) Rules, 1954, milk standards varied state-by-state. However, under the modern Food Safety and Standards Regulations (FSSR, 2011), the standards for species-identified milk (cow, buffalo, goat, sheep, camel) have been completely harmonized into uniform, single pan-India national standards, eliminating state-wise variations.
  
  Option analysis:
• Both Statement (I) and Statement (II) are true: Incorrect.
• Both Statement (I) and Statement (II) are false: Incorrect.
• Statement (I) is true but Statement (II) is false: Correct answer.
• Statement (I) is false but Statement (II) is true: Incorrect.

Heat stability of milk and influencing factors:

• Statement (I) is true: Homogenization subdivides fat globules into minute droplets, increasing the lipid surface area 4- to 10-fold. Casein micelles from the serum phase rapidly adsorb onto this new fat interface. During subsequent sterilization heating, cross-linking between adsorbed caseins on adjacent fat globules induces fat-protein clustering, significantly reducing the Heat Coagulation Time (HCT) / heat stability of whole milk.
• Statement (II) is true: Stabilizing mineral salts (citrates and phosphates) sequester ionic $Ca^{2+}$, restoring colloidal balance, while natural urea decomposes at high temperatures to buffer acidity and modify protein cross-linking, markedly improving heat stability at $140^\circ\text{C}$.
  
  Option analysis:
• Both Statement (I) and Statement (II) are true: Correct.
• Both Statement (I) and Statement (II) are false: Incorrect.
• Statement (I) is true but Statement (II) is false: Incorrect.
• Statement (I) is false but Statement (II) is true: Incorrect.

Buffalo ghee possesses a distinctly harder, firmer texture and higher melting point ($32\text{ to }38^\circ\text{C}$) compared to cow ghee ($28\text{ to }34^\circ\text{C}$) because buffalo milk fat contains a significantly larger proportion of high-melting, long-chain saturated fatty acids—notably palmitic acid ($C_{16:0}$, $\sim 32\%$ vs $\sim 27\%$) and stearic acid ($C_{18:0}$, $\sim 15\%$ vs $\sim 11\%$)—and a lower proportion of unsaturated oleic acid ($C_{18:1}$). The high concentration of these high-melting long-chain saturated acyl chains increases solid fat content at ambient temperatures, making buffalo ghee visibly harder.

Option analysis:

• Larger proportion of long chain saturated fatty acids: Correct. Explains the higher solid fat content and harder consistency of buffalo ghee.
• Larger proportion of short chain triglycerides: Incorrect. Short-chain triglycerides have lower melting points and would soften fat.
• Smaller proportion of long chain saturated fatty acids: Incorrect.
• Smaller proportion of short chain triglycerides: While buffalo ghee has slightly less butyrate than cow ghee, the primary direct cause of hardness is the larger proportion of high-melting long-chain saturated fatty acids.