To preserve scallions for a long time, it's necessary to control several aspects. This includes pre-treatment, pre-cooling, cold storage environment, stacking management, and daily inspection. The entire process is critical for high-quality scallions cold storage.
1. Control Preprocessing of scallions cold storage
A. When harvesting scallions, prioritize plants that are healthy, free from rot, insect infestation, and mechanical damage. Avoid harvesting on rainy days, as moisture can negatively affect scallions during cold storage.
B. After harvesting, trim away dry, yellow, rotten leaves and soil. Do not remove the outer protective skin; avoid washing. This is because water contact can easily cause rot and mold, making them unsuitable for scallions cold storage success.
C. Then spread them out in a cool, well-ventilated place to dry for 2-3 days to remove excess surface moisture. The scallions are ready when the skin softens. In addition, do not expose them to direct sunlight, as this will cause the white part of the scallion to lose moisture and become mealy. Proper drying is a foundation for scallions’ optimal condition in cold storage later on.
2. Pre-cooling treatment and Cold storage environment
Before storing scallions, pre-cooling treatment is essential. Air cooling should be used to quickly lower the scallion temperature to around 0°C. This prevents residual heat from the field from entering the cold storage and causing overheating and yellowing. The cold storage temperature should be stably controlled between -1°C and 0°C. It should not fall below -3°C to avoid frost damage. Relative humidity should be maintained between 85% and 95%. Too low humidity will cause the scallions to shrivel and become hollow. In contrast, too high humidity will promote mold growth and leaf rot. The cold storage air conditioner should be set to a gentle airflow setting. Moreover, the cold air should not be blown directly onto the scallion pile to prevent dehydration and drying. Effective scallions cold storage depends heavily on these environmental controls.
3. Stacking management
The stacking method determines the shelf life. Use breathable plastic or bamboo baskets to hold scallions, leaving ventilation gaps between baskets; avoid directly sealing them in plastic bags. Stack them in layers, leaving air ducts between stacks. Furthermore, maintain a 20-30cm gap between the stack and walls or air conditioning units to ensure smooth air circulation and prevent heat buildup in the center of the stack. This is also essential for proper scallions cold storage management.
In daily management, minimize the frequency of opening the cold storage door, as outside heat can easily cause condensation. Check the scallions periodically. Remove any that are soft, moldy, or frostbitten to prevent the spread of pathogens throughout the stack. During storage, strictly prevent temperature fluctuations. This is because frequent temperature increases will cause scallions to sprout new shoots and soften the white part. This routine is crucial for maintaining the quality of scallions in cold storage.
For long-term storage, you can also use perforated plastic wrap for ventilation. This can lock in humidity while allowing respiration heat to escape. With proper environmental control, the shelf life of scallions in cold storage can reach 2-3 months. This gives you optimal scallions cold storage results.
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