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To extend its shelf life, glutinous corn is typically processed through freezing cold storage. The corn is first quick-frozen in an IQF (Individual Quick Freezing) cold room and then transferred to a preservation cold storage facility, which helps maintain its freshness, flavor, and quality for long-term storage. With the right cold chain process, sticky corn can be preserved for up to 12 months.
Steps for Proper Cold Storage of Glutinous Corn
1.Selection
Remove shriveled, diseased, or mechanically damaged corn cobs.
2.Cleaning
Wash the fresh corn thoroughly to reduce enzyme activity and preserve quality.
3.Packaging
Pack in high-barrier vacuum bags, remove air to create a vacuum environment, and seal tightly.
4.Sterilization
Sterilize the packed corn three times, then inspect under controlled temperature conditions before storage.
Pre-Cooling Process for Glutinous Corn
Immediately after harvesting, fresh corn should be transported to a pre-cooling cold storage facility and cooled for 1–2 hours. Pre-cooling helps reduce field heat, slows down respiration, and ensures better freezing results.
- Forced-air cooling: Temperature maintained at 0–5°C, relative humidity 85–90%, airflow 5 m/s. Once the core temperature of the corn cob reaches 5°C, the process is complete.
- Hydro-cooling (cold water cooling): Two methods include spraying cold water over the corn or immersing it in circulating chilled water. The water is cooled by refrigeration systems and can be reused.
Long-Term Cold Storage Conditions
After pre-cooling, corn should be transferred into a low-temperature cold room for corn storage. The recommended storage conditions are:
- Temperature: -18°C
- Relative Humidity: 95–98%
Under these conditions, glutinous corn can maintain its quality and nutritional value for up to 1 year.
Storage Time of Glutinous Corn Under Different Cold Storage Conditions
| Storage Method / Cold Room Type | Temperature Range | Relative Humidity | Typical Storage Time | Notes |
|---|---|---|---|---|
| Room Temperature (No Cold Storage) | 20–25°C | 60–70% | 2–3 days | Rapid quality loss, not recommended |
| Refrigerated Cold Storage | 0–5°C | 85–90% | 7–10 days | Suitable for short-term sales & distribution |
| Pre-Cooling Cold Room | 0–5°C | 85–90% | 1–2 days | Used before freezing to remove field heat |
| Frozen Cold Storage (IQF Freezing) | -18°C | 95–98% | 6–12 months | Best method for long-term preservation of sticky corn |
| Ultra-Low Temp Cold Storage | -25°C to -30°C | 95–98% | 12–18 months | Used in industrial cold chain logistics |