It’s very important to remove defect beans before roasting for better results. Each green coffee defect beans effect the roasting process and causing a bad taste in the cup.
The effects of green coffee on roasting
Coffee plant species and type, annual harvest quality, picking and stripping method, shipping and storage conditions, defects and moisture are the factors affecting coffee roasting quality.
Each type of green coffee beans should be roasted in a different way. Different roast profiles should be applied to different beans with different roasting time, charge and drum temperature, etc.
A good roast master takes all these features into consideration. He records every information referring to the specifications of green coffee he roasts for the first time, the reactions occurring during roasting, roasting conditions, and the final specifications, and aroma.
So, when he roasts a green coffee from the same origin later, he practices the previously recorded roast profile. Dissimilar results such as different specifications and aroma indicate a problem regarding the origin or the growing conditions of the coffee. In order to obtain the required coffee specifications, roast profile should be revised then.
Shortly, when a new green coffee arrives for roasting it should definitely be tested and the defects should be controlled before roasting.
Green coffee beans’ defects
The major factor affecting the quality is the defects in coffee beans.
These defects are classified as follows in 5 groups :
- Foreign matter contamination related defects,
- Defects of the fruit, not the bean,
- Irregularities of green coffee beans,
- Visual disorders of green coffee beans,
- Taste and flavor faults.
Defects in green coffee beans cause weight and sensory loss.
Every defect has a value in international coffee standards, depending on how much the defects affect the specifications of roasted coffee :
- Green Coffee Grading, used by the New York Board of Trade (NYBOT) and Brazil
- ISO 10470 – 1993 Assessment
- ISO 10470 – 2004 Assessment
- TCVN 4193 (Vietnam)
- Indonesia Standard
- LIFFE Gradings System