The Better the Blend…

by Brian Martell

For decades now, Heritage Coffee has been promoting the "Continuum to Contentment" (© 1980 Stuart Daw) as the definitive principles leading to the ultimate cup of coffee.* 

These ten rules have helped countless coffee people to better understand what it takes to make a great cup of coffee and to diagnose why you may not be getting one. The foundation to the “Continuum” and the first rule is “The better the blend the better the brew; the poorer the blend the poorer the brew, all other things being equal.” While this may sound self evident, it truly is the cornerstone of all coffee experiences and what separates the truly exceptional coffee companies (roasters, office coffee service operators, retailers, foodservice operators, etc.) from the mediocre.

To truly appreciate what it takes to develop a superior blend of coffee beans, let’s look at some of the fundamentals of coffee cultivation. Before coffee ever darkens the doorstep of the roaster’s facility, it has to go through several steps in becoming the roaster’s raw material for the ubiquitous brew Canadians and Americans take for granted. 

The cultivation of coffee trees is quite an undertaking, with premium growers painstakingly raising seedlings in nurseries until they are about a foot (30 cm) high.  Once they reach this level of maturity, they are transplanted into the plantation and attended to with constant pruning (the shape, height and attention to the productive parts of the bush are all considered while pruning), feeding (fertilizing for proper nutritional balance) and protection (the application of pesticides to prevent devastation from infesting insects such as the coffee berry borer). 

While not all coffees are created equal, some are blessed with geographic advantages not enjoyed by their other worldly cousins. The ideal growing conditions for coffee bushes are temperate climates where the mercury doesn’t go too far above or below 75F (22C), where rainfall runs an annual average of 150 to 200 cm (6 to 8 inches), where the soil is slightly acidic, and soil that allows for good aeration of the roots with reasonable water retention. All these factors equate to ideal growing conditions for coffee and, not surprisingly, those locations in the world which produce excellent coffees usually have all these factors in spades. Coffee grows really well in the volcanic or limestone soil often found in Central and South America, Eastern and Southern Africa, Indonesia and Southeast Asia which also have the other climatic conditions mentioned above. 

To maintain the consistent temperatures needed for coffee cultivation, the majority of quality coffees are grown within 10 degrees of the equator, north or south, usually at elevation which moderates the temperature so that it is not too hot. Coffee’s limit of commercial cultivation is within the tropics (23 degrees, 26 minutes, 22 seconds either north or south of the equator), but can encounter killer frosts at the extremes of this range.

Another consideration that goes into creating better coffee beans has to do with botanical sub species of the plant generally known as coffee. Of the four commercially grown subspecies of coffee (coffea Arabica, coffea canephora, better known as Robusta, coffea liberica and coffea arabusta), the Arabicas are generally regarded as producing the finer cup of coffee. Having said that, Arabica makes up about 60% of the world’s total harvest, so what sets good Arabicas apart from lesser ones? 

Again, there are several factors that influence the quality of the green beans, but let’s suppose that the Arabicas in question were all grown in the ideal climatic and field husbandry conditions mentioned above. The two major factors that will then influence the quality of coffee will be the method used to harvest the berries, and the method used to process them into green beans. 

Harvesting coffee berries usually follows 4 main paths - manual strip, mechanical strip, manual selective, and mechanical vibration. Manually stripping the branches of coffee berries involves raking or stripping all berries off a coffee branch, which will yield all available items on that branch (ripe, green and overripe berries as well as blossoms). The method is quicker than manual selective, but yields a lower quality harvest. Mechanical stripping uses tractor mounted machines that basically do the same job, but much more quickly. Plantations using this method often must be in terrain which is not too hilly to allow safe passage of the equipment. Again, the quality of the harvest is compromised in this method as well as the health of the coffee tree. 

Manual selective harvesting yields the best harvest quality but also is the most labour intensive and therefore usually the most expensive. Pickers will selectively choose only the ripest coffee berries leaving the un-ripened fruit to be harvested at a later time while not damaging the tree. The last method of harvesting, mechanical vibration, involves equipment that will wrap around the trunk of a coffee bush and vibrate the tree to shake loose all the ripe (hopefully) fruit which then can be collected manually off the ground under the tree. While this method does try to save the tree from corporal damage, it does none the less harm the tree while not always yielding the best coffee harvest.

The processing of the coffee once it has been harvested is also crucial in determining the quality of the beans. Essentially, there are two methods of processing coffee berries into green coffee - the wet method (washed) and the dry method (natural). 

The wet method requires that the berries go through a mechanical de-pulping process that will remove the fruit from the beans leaving only the mucilage, husk, and the parchment attached to the beans. Once this step has been completed the beans are sent through “sluice ways” where water rinses over them to further remove the mucilage. In the final steps of the wet method, the coffee is sun dried in thin layers on patios or partially dried in conjunction with mechanical driers and then sent to be de-husked before possibly passing through a quality control centre. At the quality control centre, the processed green beans are graded for imperfections which generally are removed and then screened for size. 

The dry method, in contrast, allows the berries to dry completely without de-pulping before being sent to a mechanical de-husking process which will remove the dried fruit as well as the husks.  At this point, the processed green coffee might then go to be graded before being packaged in jute bags for export.  In general, washed coffees provide a cleaner cup quality with better acidity and aroma than natural coffees.

So after all that has been done at or near the plantation, the roaster must decide what will make a “better blend” of green beans to roast. Taking all the above into consideration along with following due diligence in evaluating the green coffees offered will help the roaster to decide what is a superior bean to be used as a varietal (stand alone coffee from one country or region) or in a blend. From there on, there are still 9 other rules that make up the “Continuum” to the perfect cup, to which as an operator you also must do your part in achieving coffee nirvana.

* Click here for the complete Continuum to Contentment - a Stuart Daw coffee classic.

 Questions or comments?  Reach Brian at Brian@heritage-coffee.com

 (c) Copyright 2005 Brian Martell