Evaluation of green coffee grade 1 Arabica
With a sample of 350g a physical analysis starts as follows: First the humidity and density of the coffee is measured, the humidity of imported green coffee is meant to be between 10-12%. “wet hulled” green coffee sometimes can have a slightly higher moisture content. The continuous control of the humidity during storage is important to gain knowledge of the water activity and therefore the aging of the coffee.
The green coffee samples will be inspected and the impression of the beans regarding color, consistency of the coloring and odor evaluated. The color palette ranges from blue-green to pale yellow and brownish depending on origin and age of the coffee.
Subsequently a screening will take place to evaluate the size of the beans. In order to do this, sieves with various sizes will be stacked on a device that gives electronic impulses. The result is not supposed to vary more than 5% of the contracted specifications (measured with the common procedure of the sieving). The size and conformity of the beans is as important as the humidity to determine the roasting process and the roast profile.
In the sample of the green beans no defects of category 1 and only 5 defects of category 2 are allowed. The rating of the grading will be done according to the following table explaining the “value” of the different defects.
If there are two or more defects in one bean, the defect with the biggest impact on the taste and aroma in the cup will be selected.
For the roasting process it is important to specify an individual roast profile to unfold the complex aroma of the coffee. A sample of 100g will be sample roasted and then the conformity will be evaluated. A grad 1 coffee allows no “quaker”. For the sensory analysis the coffee will be valuated during a professional cupping session. The following attributes will be evaluated: aroma, taste, after taste, acidity and body. The coffee has to be free of any odd or off taste.