Question

Butter fat stored in Nitrogen would have good keeping quality when oxygen content is not more than

• A. 0.0 ppm
• B. 0.5 ppm
• C. 1.0 ppm
• D. 1.5 ppm

Hint:

Anhydrous Milk Fat (AMF) Storage: Dissolved Oxygen target under Nitrogen gas blanketing = $\mathbf{\le 0.5\text{ ppm}}$ to prevent lipid autoxidation.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Modified atmosphere storage and dissolved oxygen limits in anhydrous milk fat: Anhydrous Milk Fat (AMF Butteroil) sparged and blanketed under high-purity nitrogen gas maintains multi-year oxidative stability only when dissolved oxygen is strictly $\le 0.5 ext{ ppm}$ ($0.5 ext{ mg/kg}$).
Key Formula or Approach:
\[ \text{AMF Nitrogen Blanketing: Dissolved Oxygen } [\text{O}_2] \le \mathbf{0.5 \text{ ppm (mg/kg)}} \implies \text{Shelf Life } > 12 - 24\text{ Months at Ambient} \]

Step 2: Detailed Explanation:
In the technology, packaging, and shelf-life preservation of Anhydrous Milk Fat (AMF Butteroil Ghee):
- Liquid butterfat is highly susceptible to free-radical oxidative rancidity during storage, initiated by reaction with dissolved molecular oxygen.
- In commercial butteroil plants:
1. Molten butterfat ($45^\circ - 50^\circ ext{C}$) is passed through a vacuum deaerator and actively sparged with food-grade Nitrogen gas ($ ext{N}_2$) prior to sealing in hermetic drums.
2. To ensure superior Keeping Quality (Shelf Life $> 12 - 24$ months) without peroxide formation, the residual dissolved Oxygen content in butter fat stored under Nitrogen must NOT be more than 0.5 ppm (0.5 mg/kg) (B).

Step 3: Final Answer:
Hence, oxygen content should not be more than 0.5 ppm, matching option (B).