The moisture content of green beans is a very important factor in the definition of quality coffee. Moisture content determines the taste of the coffee, the quality of the roast and even how much the producer earns. Green coffee beans that are ready for the coffee roasting process may appear dry, but they still contain moisture. A typical unprocessed mature coffee bean should contain roughly 45-55% moisture after being picked. Processing and drying processes will then reduce the moisture content to 10-12%. A good moisture content ensures a good tasting score, balanced acidity and a good aroma. According to the International Coffee Organization, green coffee should have a moisture content of 10-12%. During the transportation of green coffees, moisture loss may occur due to some climatic conditions and changes. There is no real threat of moisture loss unless condensed water droplets fall on the bag of coffee. The moisture content of green coffees will remain constant in the bean until the roasting time

QUALITY CONTROL IN THE DRYING PHASE

Coffee fruits tend to ripen irregularly. In many 3rd generation plantations, crops are inspected at multiple points during harvest and only picked when ripe. It is important that farmers do not mix beans with different moisture contents. Otherwise, these beans will result in an inconsistent roast. As a result, the roaster will not buy this coffee again. There are many ways to dry coffee. Mechanical dryers, terraces (Patios), awnings and field beds are different ways of drying coffee. Drying in a good climate with air flow around the coffee is very important to prevent fermentation and mold. Although field beds are generally preferred for drying, the use of terraces (patios) offers advantages at low temperatures. The reason is that the heat from the ground helps the coffee to dry. Stirring and mixing the coffee is very important as there is no air flow

EFFECTS OF UNDER-DRYING

Only beans with a moisture content of 12.5% or less can be traded. When trading coffee, the moisture content of the bag determines how much money can be made. Any deviation from the standards will greatly affect the supplier’s sales in the future. A broker who thinks that the moisture content of the shipped product is too high can cut ties with the plantation. Hygiene is also very important. Fungus and mold can form when there is too much moisture and such defects can affect the entire roast. For example, a premium AA Coffee may come at an expensive price, but may have a bad taste due to poor drying. Keeping the coffee clean and properly stored reduces the risk of mold. However, the kernels must be well dried in order to eliminate them completely

EFFECTS OF OVER-DRYING

As with under-drying, over-drying has a big impact on costs. Farmers put more coffee in each sack to compensate for the weight loss due to over-drying. Since moisture is also lost during transit, farmers pack the bags very tightly. This is both a kind gesture and to help sell more bags in the future. Too much drying also affects the quality and taste of the coffee. At 9% moisture content, a loss of aroma and freshness is expected. If the moisture content drops below 8%, the roasted beans will have no flavor. As mentioned above, a bean with a moisture content below 8% cannot be supplied and should not be sent to the consumer. Moisture content is very important when roasting coffee. Since water conducts heat, the moisture in the bean provides a way for the heat to transfer to the center of the bean. In beans with low humidity, the outside of the bean roasts very quickly while the inside does not cook, giving us flavors of herbs and grass. The roaster temperature can be set for slow roasting because of the poor thermal insulation of low moisture beans. However, slow roasting gives us bread-like and cooked flavors.