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Golden pear storage and preservation technology
1. Storage Technology Points
1.1 Timely Harvesting of Golden Pears in North China
The optimal harvesting period for golden pears in North China is between September 20 and 30. At this time, the fruit has fully matured, accumulated nutrients, and exhibits the best storage stability. Harvesting too early (before September 10) can lead to a higher rate of rotting during storage, as well as brown discoloration of the peel. On the other hand, late harvesting (around early October) increases the risk of brown scald, with reported rates reaching up to 18.94%. During the harvesting process, it's crucial to handle the fruit carefully to avoid bruising, which can significantly reduce quality and shelf life.
1.2 Grading of Golden Pears
Grading is essential to ensure product standardization. In China, there are four grading standards: national, industry, local, and corporate. Currently, golden pears are mainly graded by weight using manual selection rather than automated sorting machines. This method lacks efficiency and may not consistently meet quality requirements.
1.3 Packaging Methods
Packaging includes both outer and inner layers. The outer packaging typically consists of sturdy, moisture-proof cartons that hold 15–20 kg of fruit. These containers are designed to be lightweight, durable, and cost-effective. For inner packaging, fruits are often wrapped in materials such as fresh-keeping paper or plastic bags. Experiments have shown that using 0.013mm thick polyethylene film bags for individual fruit packaging reduces natural loss and rot, while maintaining good preservation. However, thicker films can lead to black heart disease, so it’s important to use the correct thickness for optimal results.
1.4 Precooling
After harvest, golden pears are usually at high temperatures. If stored in cellars without proper cooling, they will spoil quickly. Therefore, precooling is essential to remove field heat and extend storage life. It is recommended to cool the fruit as quickly as possible at low temperatures, while protecting it from direct sunlight and rain. Studies show that golden pears can tolerate rapid precooling, allowing them to be placed directly into cold storage after harvest.
1.5 Storage Period Management
1.5.1 Disinfection and Pest Control
Disinfecting the storage area one month before and after storing golden pears helps reduce microbial infections and fruit rot. Common disinfectants include sulfur, formaldehyde, bleach, and sodium hypochlorite. Additionally, rodent control is critical—sealing holes, using traps, and applying poison baits can help prevent infestations.
1.5.2 Stacking and Arrangement
Fruits should be neatly stacked in the cold storage to allow for proper air circulation and space utilization. A sleeper should be placed at the bottom of each stack, with a gap of 2–5 cm between boxes. The height of the stack depends on the box’s strength, but there should be about 60 cm of clearance from the ceiling. Also, leave at least 30 cm from walls and air vents, and ensure clear pathways for easy access.
1.5.3 Temperature Control
Thermometers should be placed in different areas of the storage facility to monitor temperature variations. The ideal storage temperature for golden pears is between 0°C and 2°C, with minimal fluctuations to maintain quality.
1.5.4 Humidity Management
Relative humidity should be maintained between 85% and 90%. If humidity is too high, dry sawdust or quicklime can be used to absorb excess moisture. When humidity is low, water sprinkling, wet sawdust, or wet grass curtains can help increase it.
1.5.5 Gas Composition Control
In modified atmosphere storage, controlling carbon dioxide and oxygen levels is crucial. Using 0.01–0.02 mm thick polyethylene bags for individual fruit packaging prevents issues like black skin and carbon dioxide toxicity, resulting in excellent storage performance.
1.5.6 Ventilation
Proper ventilation is necessary to remove heat, harmful gases, and excess carbon dioxide. It also helps replenish oxygen and ensures even temperature distribution. Ventilation should be done when the temperature difference between inside and outside the warehouse is minimal to avoid large fluctuations.
2. Main Storage Diseases and Prevention
2.1 High COâ‚‚ and Low Oâ‚‚ Damage
Golden pears are highly sensitive to carbon dioxide due to their high water content and strong physiological activity. Long-term storage in high COâ‚‚ or low Oâ‚‚ environments can cause damage. Maturity level and storage temperature also influence the likelihood of COâ‚‚ injury. To prevent this, COâ‚‚ levels should be kept below 3%, and oxygen levels between 5% and 8%.
2.2 Cold and Frost Damage
Golden pears can withstand 0°C storage, but if the temperature drops below -5°C, the fruit may freeze. Rapid cooling upon entering the cold storage can also cause internal browning, known as black heart disease, which is a form of cold injury.
2.3 Peel Browning
The peel of golden pears is prone to browning due to its high phenolic content and polyphenol oxidase (PPO) activity. During storage, dehydration and membrane damage can lead to increased permeability and oxidation, causing browning. To reduce this, consider:
- Harvesting at the right time to improve maturity
- Storing at low temperatures to minimize moisture loss
- Applying calcium treatments before or after harvest
- Using protective bags during the growing season
- Avoiding mechanical damage during handling and packaging