Quality Control

• Physiological Zero in Embryology:
• The physiological zero temperature for avian eggs is defined as the temperature below which embryonic cell division (blastoderm development) is suspended in physiological arrest:

• Hatching eggs awaiting incubation are stored at $15 - 18^\circ\text{C}$ (well below physiological zero) to maintain dormancy. If eggs are stored between physiological zero ($24^\circ\text{C}$) and incubator temperature ($37.5^\circ\text{C}$), abnormal embryonic development occurs, causing early embryonic mortality.
• nalysis:
• (24 °C): Correct standard physiological zero temperature.

Correct option: (3) 24°C

• Bulgarian Buttermilk $\to$ (III) L. bulgaricus: High-acid fermented milk produced by monoculture inoculation of Lactobacillus delbrueckii subsp. bulgaricus, producing up to $2.0\text{--}4.0\%$ lactic acid.
• Kumiss $\to$ (IV) L. acidophilus and L. bulgaricus: Traditional fermented mare's milk involving both lactic acid bacteria (L. bulgaricus, L. acidophilus) and lactose-fermenting yeasts (Kluyveromyces marxianus) producing lactic acid and alcohol ($1\text{--}2.5\%$).
• Kefir $\to$ (II) Streptococcus lactis and Betabacterium caucasicum: Effervescent fermented milk prepared using symbiotic kefir grains containing lactic streptococci, lactobacilli (Betabacterium caucasicum / L. kefir), and yeasts.
• Yoghurt $\to$ (I) L. bulgaricus and Streptococcus thermophilus: Classic symbiotic 1:1 starter culture producing acetaldehyde, diacetyl, and lactic acid.

Correct option: (2) (A) - (III), (B) - (IV), (C) - (II), (D) - (I)

• Assertion (A) is True: In a centrifugal disc-bowl cream separator, the less dense cream migrates towards the central axis of rotation and discharges through the inner/upper cream outlet, whereas skim milk discharges through the outer/lower nozzle.
• Reason (R) is False: The specific gravity of milk fat is $0.93$, which is lower than the specific gravity of skim milk ($1.036$). Because milk fat is lighter, centrifugal force drives denser skim milk to the bowl periphery while fat globules displace inwards towards the center.
• Conclusion: (A) is true, but (R) is false.

Correct option: (3) (A) is true but (R) is false