Subtopic: Processing of seeds, spices, fruits and vegetables
Question Statement:
In the processing of spices such as black pepper and cardamom, cryogenic grinding utilizing liquid nitrogen ($-196^\circ\text{C}$) is advantageous primarily because:
Options:
(A) It freezes the spice below its glass transition temperature, preventing loss of volatile essential oils and oily gumming of grinding surfaces
(B) It eliminates the requirement of sieving and grading the ground spice powder
(C) It bleaches the spice pigments to achieve pure white appearance
(D) It completely converts volatile terpenes into non-volatile fatty acids
Answer Key:
A
Step-by-Step Solution & Explanation
Conventional mechanical grinding dissipates heat, raising temperatures up to 80–90°C and vaporizing fragile volatile aromatic oils. Cryogenic grinding rapidly chills the spice below its glass transition temperature, causing brittle fracture without heating, conserving volatile oils and eliminating gumming on screens.