Very bad coffee: defects in green coffee beans
Where do bean defects come from?
Coffee is an extremely delicate raw material: roasters and other coffee professionals repeat this like a mantra. Those tough-looking dark beans are actually easily damaged, and a small oversight can spoil their distinctive aroma. When assessing beans' potential and value, Q graders often detect defects caused by harvesting mistakes, poor processing or unsuitable storage. There are many opportunities to spoil coffee long before it reaches a roastery. Do not believe us?
In practice, green beans can be damaged at any stage. If a worker harvesting by stripping puts a few unripe cherries in the basket, the seeds inside may turn out to be underdeveloped. During processing, a seed might remain in contact with the pulp too long, begin fermenting and acquire the bouquet of a very, very young wine. Finally, someone might carelessly leave the morning's catch beside the coffee sacks in a warehouse, giving the beans the familiar aroma of mountain trout and upsetting a Q grader once again. As you can see, defects are easily created and may prevent a product from winning approval.
A short list of major mistakes
When assessing bean quality and value, the tester identifies green-coffee defects and records them on a special SCA, Specialty Coffee Association, form. To make the assessment transparent, every defect detected in a 350-gram sample is recorded in a table. More than five secondary defect points, or even one primary defect, means the beans do not qualify as specialty coffee.
Which flaws can reduce a bean's value? Fermented, cracked or unripe beans certainly can: their flavour would spoil every sip of morning espresso. As soon as these are detected, the sample is rejected and drops to a lower category in the Q grader's assessment. Foreign material can also disqualify a coffee. Bits of twigs, stones or even small insects introduced through poor storage would hardly improve a little black coffee.
What can be forgiven?
Smaller defects are permitted in specialty coffee; nobody is perfect. But remember, a sample aspiring to that status can have no more than five. For comparison, “off” coffee, the lowest fifth grade common on discount shelves, may have as many as 86. The Q grader examines the sample carefully for small chips, cracks, water damage, insect marks, uneven surfaces or insufficiently ripe beans. Every defect is diligently recorded, and the final penalty total determines the coffee's grade.
Defects in coffee are not the end of the world. Yet the ease with which small production oversights can damage beans often leads to a multiplication of seemingly innocent flaws. Despite the strictness of Q graders' assessments, this quality control is worthwhile. After all, none of us wants a fresh grasshopper leg in a morning coffee lazily dripping through a brand-new Chemex, do we?