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Harvesting and Understanding SCAA Defects

Coffee....  is a fruit. 

It's easy to forget that when we strip the flesh from it, roast it, grind it and extract liquor from it.  Have you ever tasted the difference between a perfectly ripened peach and one picked too early in order to export it overseas?  The difference is astounding!  The sweet, juicy, crisp peach satisfies your tastebuds like nothing else.   Why would we expect differently from coffee?  Harvesting cherries at the wrong time could be what makes your coffee amazing or what gives you the same indistinct coffee as everyone else.

According to the Specialty Coffee Association of America’s (SCAA) “Arabica Green Coffee Defect Handbook,” improper harvesting of coffee cherries influences seven potential defects.

Picking an unripe cherry could potentially give you an immature, broken, chipped, cut, or quaker bean. Picking an overripe cherry could give you either a full or partially sour bean, as well as a full or partially black bean.

Two of the defects listed in the handbook, both “Cherry Pod” and fungus, are potentially created by harvesting cherries from the ground. The remaining five defects potentially develop from picking the cherries from the tree at the wrong time.

Because there is a direct correlation between bean quality and cup quality, it is safe to say that each one of these listed defects above impacts the quality and flavor of the cupped coffee in a negative way. Easily stated, properly picked cherries produce a better quality of coffee as compared to improperly picked cherries.

The SCAA Arabica “Green Coffee Defect Handbook” states the following about cup quality of each of the defects:

  • Immature/Quaker beans generally impart grassy, straw-like or greenish flavors and is the main source of astringency in coffee. (Like eating any other unripe fruit, you will taste more of the structural material of the fruit and not the perfectly developed sugars and acids that people love)

  • Broken/Chipped/Cut beans can cause earthy, dirty, sour, or fermented beans. (This is due to the bacteria growth that takes place in and on the cracks and chips)

  • Dried Cherry/Pods/Fungus bean imperfections can cause fermented, moldy, or phenolic taste. (What a harvester might see as a opportunity not to waste, the barista see's as a road block to a clean cup)

  • Full/Partial Sour and Full/Partial Black bean imperfections can produce sour, fermented, or even a stinker taste. (Allowing coffee cherries, aka the fruit, to over-ripen on the tree has dire consequences to flavor of the cup)

  • Immature beans can be filtered out systematically during the washed method of processing coffee by removing the floaters when the coffee is submersed in water. While this is an effective method, it is not necessarily efficient due to the large amounts of beans that are removed. It is also not extensive in removing all defects. In order to produce a washed coffee efficiently or a high value natural coffee, proper picking remains imperative.

While improving harvesting may be as simple as declaring each bean as either ripe or not ripe, implementing high harvest standards can be very complex due to the fact that all specialty coffee is harvested by manual labor. Thus, improving harvesting requires a highly compensated and well trained work force in order to achieve higher standards. 

Having a good understanding and enough knowledge about the particular variety that is being harvested is crucial for harvesting ripe cherries. Each and every variety has its own color profile at full maturity. Below is a photo that clearly shows the differing colors of different coffee varieties from immaturity to full maturity. 

Additional ways to consider for improving coffee harvesting are:

  • Compensating harvesters based on the quality of cherries that they deliver to the mill. The quality can be measured with a cherry ripeness board in order to establish a sample percentage of their delivery, grading how much is ripe versus unripe.

  • Display color charts in several locations around the coffee farm or receiving bay of the mill, in order to clearly show the color of your coffee varieties ripeness color.

  • Do not mix or interplant different varieties of coffee in the same field.

  • Harvest a particular tree/field more often in order to pick the cherries as they ripen.

  • When harvesting, double check the color of the cherry closest to the stem as it is the last section of the branch to change color.

  • Twist cherries off the stem with ease. If they will not twist off easily, they are not ready to be harvested.

Article written by Zachary Price, Torch Farmer Network Director