China cold storage solution provider
Storing onions effectively is crucial for maintaining quality and extending shelf life. Among the many available methods, Controlled Atmosphere (CA) cold storage has proven to be the most effective for long-term preservation of onions.
By adjusting the levels of oxygen, carbon dioxide, and humidity inside the cold room, CA storage significantly slows down onion respiration and decay, ensuring freshness for extended periods. This method also allows farmers and distributors to store in-season and sell off-season, maximizing economic value.
✅ Key Steps for Onion Storage in CA Cold Rooms
1. Harvesting
Onions should be harvested on dry, sunny or cloudy days. Avoid harvesting during rainy weather to prevent excess surface moisture, which can lead to rot during storage.
2. Sorting & Grading
After harvesting, onions must be graded by size and quality. Remove damaged, diseased, or underdeveloped bulbs to reduce the risk of spoilage.
3. Pre-cooling
Pre-cooling helps reduce respiration and slows down decay. Use forced-air cooling or directly place onions into a pre-cooled cold room. The faster the cooling, the better the storage performance.
4. Storage Conditions
- Temperature: Optimal storage temperature is 0~1°C, with a fluctuation margin of ±1°C. Avoid rapid temperature changes exceeding 2°C.
- Humidity: Maintain relative humidity at 80% to preserve moisture and flavor. If humidity is too high, controlled ventilation is needed.
- Oxygen: Maintain O₂ levels between 3%–5%
- Carbon Dioxide: Keep CO₂ concentration between 8%–12%
These conditions slow down metabolism and microbial activity, ensuring minimal weight loss and decay.
Controlled Atmosphere (CA) cold storage device
✅ Proven Results
Tests show that after 90 days in CA storage, onions retain their original color, aroma, and flavor, with a marketable yield of over 90%. This makes controlled atmosphere storage one of the most reliable solutions for large-scale onion preservation.