Storing parchment coffee (coffee beans still in their protective husk) and green coffee beans is a familiar yet critical step for farmers and coffee storage facilities. Improper storage can significantly affect both quality and market value.
Storing Parchment Coffee
Table of Contents
Key factors affecting storage:
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Moisture content of the coffee beans and the surrounding environment
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Temperature of the coffee mass and the surrounding air
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Air circulation inside the coffee mass
Common storage methods:
1. Dry storage
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Sun drying
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Hot air drying
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Dry air drying
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Using chemical desiccants such as H₂SO₄ or CaCl₂
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2. Active aeration storage
This method uses the natural porosity of the coffee mass by blowing dry, cool air through it multiple times to lower both temperature and moisture.
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Air must be evenly distributed throughout the coffee mass.
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Sufficient dry, cool air is needed to reduce temperature and moisture.
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Only ventilate when the outside air’s humidity is low, so that the bean moisture decreases.
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Outside air temperature must be lower than the coffee mass temperature.
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Low-temperature storage
At low temperatures, the metabolic activity of the beans, as well as microorganisms and insects, is greatly reduced.
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Cold, dry air is blown through the coffee mass.
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Due to coffee’s low thermal conductivity, the cool air remains for a long time, slowing biological activity and extending shelf life.
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In Vietnam’s climate, this is rarely applied, but farmers can take advantage of naturally cool, dry winter days.
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Hermetic (sealed) storage
This method stores coffee with little or no oxygen.
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In the absence of oxygen, respiration of living organisms nearly stops, shifting to anaerobic conditions.
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Microorganisms and pests—mostly aerobic—are suppressed or eliminated.
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Oxygen can be reduced by introducing carbon dioxide (CO₂) into the coffee mass. The remaining oxygen is consumed through the beans’ natural respiration.
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Storing Green Coffee Beans
Because the protective husk and silverskin have been removed, green coffee beans are more vulnerable than parchment coffee and require stricter control.
Methods
Storage in bags (jute or cloth sacks)
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Moisture content of green beans must be below 13%.
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Impurities should be minimal; for Grade I and II coffee, foreign matter should be less than 0.5%.
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Choose a well-insulated, dry warehouse.
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Clean and disinfect the storage area before stacking bags.
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Do not place bags directly on the floor or against the wall: keep 0.3 m off the floor and 0.5 m from the walls.
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To avoid compaction from the weight of upper layers, rotate or rearrange the bags every three weeks.
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Bulk storage in silos
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Coffee beans are stored loose in sealed silos made of sheet metal, concrete, or good-quality wood.
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This saves on packaging costs and allows longer storage time.
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It also optimizes warehouse space and prevents the coffee mass from compacting, which helps maintain the beans’ loose texture.
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Aromatic compounds and a slight release of nitrogen gas may occur naturally during storage.
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Properly following these guidelines helps preserve the flavor, aroma, and value of coffee beans for the export market.