STiR coffee and tea magazine

Volume 4, Number 1

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40 STiR tea & coffee industry international O By Katrina Ávila Munichiello Detecting Defects ptical sorting equipment has played a valuable role in the coffee industry for decades. These machines have the critical job of identifying a wide array of defective coffee beans and extracting them with a precision that reduces unnecessary losses of quality product. Producers are experiencing a moment when drought and coffee leaf rust have been impacting some of the most important coffee- producing regions while at the same time, beans are commanding some of the highest prices to date. The cleanest and best quality samples of beans will receive the highest financial reward. But how are the current optical sorting machines able to help coffee sellers achieve this goal? Rooting out the problems There are several types of defects commonly found in coffee beans. There are color defects in which a bean is the wrong hue because it has been impacted by mold, fungus, or poor development. Other coffee plants produce harvests that have been damaged by insects. Some beans simply do not mature or grow properly, leaving them too light or shriveled. With roasted beans, producers may find that they have under-roasted or over-roasted the product, ruining its quality. There can also be foreign objects mixed in with the beans, including sticks, metallic particles, and rocks. Coffee leaf rust has become a sizeable problem. Rust is an infection that begins to emerge on the leaves of coffee trees as small yellow spots. Over time the spots become larger and orange lesions develop on the bottom of the leaves. The fungus causes the leaves to drop too soon, and because the urediniospores that have developed can sur- vive six weeks, new leaves are likely to also become infected. The disease can be further spread by wind and rain. Coffee leaf rust has caused great harm to coffee trees, making them susceptible to damage by insects called coffee berry borers or Broca. Whether arising from biology or from poor handling of the product during harvest or processing, any of these defects can ruin the quality of a cup of coffee. "Any kind of stress on the trees will increase the number and types of defects found in the green coffee," says Johanna Bot, sales director at Satake USA. "Both the increasing demand for specialty coffees, as well as the challenges of cli- mate change, mean that high quality optical sorters will continue to be of great value to coffee exporters." A Xeltron optical sorter (above) separating the good beans from bad One of Delta Technology's TCS-2 optical sorters culling beans to add value at Urbina's coffee processing plant in Matagalpa, Nicaragua.

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