Question

Cryogenic grinding improves the aroma of spices by minimizing the loss of essential oils of about ________.

• A. 3-10 %
• B. 10-15 %
• C. 15-43 %
• D. 30-50 %

Hint:

- Conventional grinding $\rightarrow$ High heat $\rightarrow$ Loses $30\text{--}50\%$ of volatile oils.
- Cryogenic grinding (using liquid $\text{N}_2$ at $-196\text{ }^\circ\text{C}$) $\rightarrow$ Extreme cold $\rightarrow$ Restricts oil loss to just $3\text{--}10\%$.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Spices contain delicate, volatile essential oils that are responsible for their characteristic aroma, flavor, and therapeutic properties.
Conventional grinding methods generate heat, which can degrade these heat-sensitive compounds.
Detailed Explanation:
- Conventional Grinding: The high-speed impact in hammer mills or pin mills raises temperatures up to $43\text{--}95\text{ }^\circ\text{C}$. This heat causes a significant loss of highly volatile essential oils (often up to $30\text{--}50\%$), reducing the quality and aroma of the ground spice.
- Cryogenic Grinding: Liquid nitrogen (operating at $-196\text{ }^\circ\text{C}$) is used to cool the spices before and during grinding.
- This cooling makes the spice extremely brittle, allowing it to fracture easily into a fine powder with minimal mechanical friction.
- The low operating temperature prevents thermal degradation and minimizes the loss of volatile essential oils to only $3\text{ to }10\%$ (A). This preserves the original aroma, color, and flavor of the spice.

Step 2: Final Answer:
Cryogenic grinding improves spice quality by minimizing the loss of essential oils to approximately 3-10 %.