Thursday, September 17, 2009

Does processing method impact coffee flavor?

It makes sense, right? Processing affects the final flavor. Many things can go wrong between cherry and dried green coffee, most of which can be tasted in the cup. We all know this step is important. Nearly every source available says that the type of processing affects the final flavor. Most green bean suppliers pay homage to this general notion by providing processing information with their product. The Coffee Research Institute claims, “The processing method used on a coffee is usually the single largest contributor to the flavor profile of a coffee.” K.C. O’Keefe’s coffee quality formula puts processing at 10 percent of the creation step and lists processing and drying at a combined total of 55 percent of the conservation step.

So, if we all know it has an impact, what is the impact? How do we describe it? The Coffee Research Institute attributes nutty, sweet flavors to dry-processed Brazilian coffees when compared to wet-processed coffees from the same region. This agrees with the general sentiment about dry and natural processed coffees. But do we know this, or do we just feel it? Is there data?

I gathered cupping scores from Sweet Maria’s Latin American and African offerings and compared the averages of the dry-, natural-, and wet-processed coffees. The graph at the top shows those averages. Surprisingly, the wet processed coffees were sweeter on average, and dry-processed coffees were no more complex than wet coffees. Does this mean that any given coffee would be sweeter if processed wet than if it were processed dry or natural? Not at all. This only demonstrates the lack of good information.

The problem is that every location is different in climate, soil, management practices, and varieties grown, so even coffees from the same region are very different before processing. So when a taster tastes the coffee and says one is sweeter than the other it’s impossible to tell whether the sweetness comes from the processing or from the climate, soil, or variety. I have not found a single academic study that compared the various methods side-by-side. If anyone has solid information, let me know.

Over the next few months I’ll be gleaning what I can from the flavor literature, looking at what the possible impacts might be based on what scientific knowledge we do have. This is probably the biggest gap in current understanding of knowledge of quality along the coffee supply chain. Processing is an essential component of coffee quality, and the coffee world needs to know the different impacts the various methods have on flavor components.

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