Livestock Products Technology- ICAR JRF/SRF 2024

• Foaming Capacity of Egg White (Albumen):
• Egg white proteins (primarily ovalbumin, ovotransferrin, and globulins) possess remarkable amphiphilic surfactant properties.
• Upon mechanical whipping, proteins rapidly unfold and orient at the air-water interface, coagulating slightly to form a viscoelastic film that traps air bubbles into a stable foam.
• Meringues and Angel Food Cake:
• Meringues rely entirely on the volume and thermal stability of whipped egg white foams sweetened with sucrose.
• In contrast, mayonnaise and salad dressings rely on egg yolk lecithin for emulsion stabilization; scrambled eggs rely on thermal protein coagulation.

Correct option: (1) Meringues

• Nisin Production and Biology:
• Nisin (E234) is an internationally approved ribosomally synthesized antimicrobial peptide (bacteriocin / Class I lantibiotic) containing unusual amino acids (lanthionine and $\beta$-methyllanthionine).
• Produced naturally by the food-grade lactic acid bacterium Lactococcus lactis subsp. lactis.
• Mode of Action: Binds to lipid II in Gram-positive bacterial cell walls, forming stable trans-membrane pores that cause rapid leakage of ions and ATP, effectively inhibiting foodborne pathogens such as Listeria monocytogenes and Clostridium botulinum spores.

Correct option: (3) Lactococcus lactis

• Biochemical Differentiation of Horse Meat (Chevaline):
• Iodine Value of Fat: Horse fat has a characteristically high iodine value ($80\text{ to }95$) due to abundant polyunsaturated fatty acids, whereas beef and mutton fat have low iodine values ($35\text{--}50$).
• Muscle Glycogen Content: Equine skeletal muscle stores exceptionally high levels of resting glycogen ($\gt 0.5\text{ to }1.5\%$, detectable via the classic Trommer's or iodine test), compared to $\lt 0.1\%$ in post-rigor beef or mutton.
• Linoleic / Linolenic Acid: Horse fat uniquely contains $15\text{--}20\%$ linolenic acid ($C_{18:3}$), compared to $\lt 1\%$ in bovine tallow.
• Marbling (C): Horse meat is characteristically lean with virtually absent marbling (intramuscular fat).
• Conclusion: Statements (A), (B), and (D) are correct.

Correct option: (1) (A), (6) and (D) only.