The most familiar systems for counting defects are the Specialty Coffee Association (SCA) and Coffee Quality Institute (CQI) format and the Brazil/New York method. Using 300 grams of green coffee, a grader will pick and categorize different defects.
Quakers are identifiable only when the coffee has been roasted. Not all green coffee identified as underripe results in quakers, and vice versa. Both CQI and SCA recognize underripe as an allowable secondary defect, but the SCA defines specialty coffee with zero tolerance for quakers.
Even if coffee makes it all the way from picking to shipping with no problems, there are still risks for defects. Beetles are notorious pests, chewing their way through dried coffee and reproducing prolifically. Storage insect damage holes tend to be much larger than those from insect damage that occurs in the field. Coffee infested with beetles, or with moths or worms that eat the jute bags, must be quarantined and purged by freezing or oxygen removal.
Poor conditions are the other main culprit of storage-damaged coffee. Hot and humid conditions can exacerbate aging. In wet conditions, coffee may re-absorb water and fade in appearance as well as flavor. Black spots can occur if coffee has been poorly dried and pockets of water within the bean cause rot, and mold can develop on the surface of the coffee as well. Stable storage conditions will help prevent these defects. Dried coffee, whether in parchment or green, prefers environments near 65 degrees F/18 degrees C with moderately low (40 to 60 percent) relative humidity.
As both coffee quality and sustainability become increasingly important, there is growing interest in understanding how ecological quality affects coffee quality. Here we analyze, for the first time, the state of evidence that ecological quality, in terms of biodiversity and ecosystem functions, impacts the quality of Coffea arabica and C. canephora, based on 78 studies. The following ecosystem functions were included: pollination; weed, disease, and pest control; water and soil fertility regulation. Biodiversity was described by the presence, percentage, and diversity of shade trees. Coffee quality was described by the green bean physical characteristics, biochemical compounds, and organoleptic characteristics. The presence and diversity of shade trees positively impacted bean size and weight and reduced the percentage of rejected beans, but these observations were not consistent over different altitudes. In fact, little is known about the diversity of shade trees and their influence on biochemical compounds. All biochemical compounds varied with the presence of shade, percentage of shade, and elevation. Coffee beans from more diverse tree shade plantations obtained higher scores for final total organoleptic quality than simplified tree shade and unshaded plantations. Decreasing ecological quality diminished ecosystem functions such as pollination, which in turn negatively affected bean quality. Shade affected pests and diseases in different ways, but weeds were reduced. High soil quality positively affected coffee quality. Shade improved the water use efficiency, such that coffee plants were not water stressed and coffee quality was improved. While knowledge on the influence of shade trees on overall coffee quality remains scarce, there is evidence that agroecosystem simplification is negatively correlated with coffee quality. Given global concerns about biodiversity and habitat loss, we recommend that the overall definition of coffee quality include measures of ecological quality, although these aspects are not always detectable in certain coffee quality characteristics or the final cup.
One study also analyzed the interacting effects of post-harvest processing methods (dry and wet processing) and shade on coffee bean physical quality score of C. arabica (primary defects + secondary defects + odor; score over 40 points) in Ethiopia (Worku et al. 2018). These authors found that coffee beans grown unshaded had higher physical quality scores than coffee beans grown shaded. Moreover, they reported that coffee beans grown unshaded that were dry processed obtained higher scores on physical quality compared to wet processed coffee beans. However, bean physical quality scores of coffee beans grown under shade did not differ significantly between dry and wet processing. Worku et al. (2018) obtained unexpected results, since they hypothesized that shade and wet processing produce good quality coffee beans. They suggested further research using larger and repeated experiments to arrive at reliable conclusions regarding these interactions. 2b1af7f3a8