Harvesting and post-harvest coffee are important stages that determine the quality of the coffee beans before they are served in the cup. The harvesting process is usually carried out selectively, by picking coffee cherries that are fully ripe to ensure optimal taste.
After that, stage postharvest includes various important processes such as peeling, fermentation, washing and drying. Each step must be carried out carefully because small mistakes, such as excessive fermentation or uneven drying, can reduce the quality of the coffee beans. With proper handling, Indonesian coffee beans are able to produce a distinctive taste that is in demand in local and international markets.
1. Coffee Harvest Time
Coffee plants have a flowering period that is not simultaneous, occurring 3-4 times a year. This cycle includes preliminary, mid (main) and late flowering, depending on the type of coffee and climatic conditions. Some coffee plants even flower all year round.
This irregularity in flowering causes the coffee harvest to take place in stages, consisting of preliminary, main and final harvests. The type of coffee also determines the duration of the harvest; Robusta is generally harvested 8โ11 months after flowering, while Arabica requires 6โ8 months.
Accurate harvest time is very important to maintain coffee quality. Coffee berries that are ready to harvest are marked with a bright red color, indicating the optimal level of ripeness. Proper harvest management ensures high quality and competitive coffee yields.
2. Guide to Harvesting Coffee
The correct coffee harvesting process is an important step to ensure the quality of the coffee produced. The following are four commonly used methods of collecting coffee harvests:
- Selective Picking: This method only picks coffee cherries that are truly ripe. Fruit that is still green is left on the tree for 1-2 weeks until it is ready to be harvested at the next session. In this way, the harvest is of high quality because only ripe fruit is processed.
- Semi-Selective Picking: In this method, picking is done on fruit dompolan which is mostly ripe. After that, other ripe dompolan are picked in the next session. This approach maintains fruit quality without neglecting time efficiency.
- Careful Picking: This method refers to collecting coffee cherries that are too old and have fallen naturally because they were harvested too late. Lelesan fruit is usually dry, but the quality tends to be lower than fruit that is picked directly when it is ripe.
- Knitted Picking: In this method, all the coffee cherries are picked at once, including the berries that are still green. This kind of picking is generally done at the end of the harvest, when no further picking sessions are planned. After picking, the coffee berries are sorted to separate dry fruit (lelesan), ripe fruit and green fruit. This sorting aims to optimize the post-harvest process so that each category of fruit can be processed according to its characteristics.
3. Processing of Coffee Products
Coffee processing must be done immediately after harvesting to maintain its quality. Typically, the coffee traded is in the form of dry beans without the fruit flesh and parchment skin, known as green coffee. There are two main methods of coffee processing: dry processing and wet processing.
In dry processing, freshly harvested coffee cherries are dried under the sun for 10-14 days, being turned regularly to ensure even drying. Alternatively, the fruit skin can be removed using a pulper machine before drying. Once dry, the coffee is stored as parchment coffee, and the husk and parchment are removed when ready to sell. Good quality coffee from dry processing should have a moisture content of no more than 12%, foreign matter (like stones, twigs, and dirt) up to 0.5%, and should be free from bad smells, mold, mildew, or live insects.
In wet processing, the coffee fruit is peeled using a pulper machine or manually. The beans are then cleaned from mucilage through fermentation, which can be either wet or dry.
In wet fermentation, the beans are soaked overnight and then washed with running water until smooth. In dry fermentation, the beans are piled in a tank and covered with a burlap sack for 36-48 hours before being washed clean.
After fermentation, the beans are dried and then separated from the parchment and husk. Good quality coffee from wet processing should have a moisture content of no more than 13%, foreign matter up to 5%, and should be free from bad smells, mold, mildew, or live insects, with no more than 1% passing through a 3 x 3 mm sieve, or 5.6 x 5.6 mm for larger beans.
4. Storage
Storing coffee beans is a crucial stage in maintaining the quality of the harvest. Each type of coffee bean quality is separated according to its classification and put into clean and safe sacks.
The sacks are then stored in a dry place, with good air circulation, and protected from exposure to direct sunlight or excess humidity. This step aims to prevent damage to the beans due to mold, pests or quality degradation, so that the coffee’s distinctive aroma and taste is maintained until it is ready for further processing.