Q90: Enzymatic phase of rennet action is: - Livestock Production Management & Livestock Products Technology - ICAR AIEEA PG 2024 - Animal Sciences | Agrigyan

Rennet coagulation of milk occurs in two distinct phases: (1) Primary (enzymatic) phase, where chymosin cleaves kappa-casein at Phe105-Met106; this phase has a very low temperature coefficient ($Q_{10} \approx 1.3-1.5$) and can proceed even at cold temperatures ($0-5^\circ\text{C}$), functioning virtually independently of temperature compared to the secondary coagulation phase. In contrast, the secondary phase is strongly temperature-dependent ($Q_{10} \gt 15$) and requires calcium ions. NTA officially keyed Option 1 as correct.