Green Bean Coffee faults

Green bean coffee faults
Green coffee bean faults or defects are usually caused by natural and human failures in the picking, processing, drying, sorting, storage, or transportation stages of the green coffee bean production. Further human failures can create coffee faults at the roaster and in the distribution and storage of the roasted coffee beans.

Apart from the sticks and stones often found in the coffee batch, the most common coffee fault in the green coffee bean is detected by the discoloration of the green bean. Here is what green beans should look like.
Discoloration in the green beans is created from the oxidation of the damaged areas of the bean and off-flavors will result. Discolored beans roast unevenly, age rapidly, and even just a few are capable of significantly reducing the overall coffee taste.

The most common discoloration is identified by the black, deep blue, or dark brown surface areas on the green bean. Green beans with more than 25% of this discoloration are known as Black Beans (on the New York Coffee Exchange) and are considered to have a significant detrimental effect on the coffee taste.

'Black Beans' and other types of discolorations are typically caused by:

• harvesting immature coffee cherries
• harvesting dead cherries that fell naturally from the trees.
• exposure to water and heat at the wrong time in the process
• wet processed beans that have been cut or bruised by the machinery during the pulping stage
• beans that were dried too rapidly causing them to fade in color
• faulty fermentation, improper washing, over drying, or by harvesting over-ripe coffee cherries creating a brown or rust color on the green coffee bean
• uneven drying during processing causing blotchy discolorations.
• green bean that have been left too long in the fermentation tanks under the natural fermentation method and have become discolored by putrefactive bacteria which attacks the proteins causing the beans to sour. These are often identified by their yellow or redish brown color.
• picking over ripe coffee cherries that become 'stinkers' and produce an unpleasant or even foul taste. One or two stinker beans can spoil a whole batch of coffee.

Common green bean defects caused by natural failures that can also produce poor tasting coffee include:

• insect-damage i.e. Coffee Berry Borer (CBB) is one of the most significant pest problems for coffee farmers.
• disease damaged coffee beans mostly caused by fungus (mold). i.e. Coffee Leaf Rust (CLR), Coffee Berry Disease (CBD)