Understanding coffee bean density

Understanding coffee bean density

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Coffee bean density is a crucial knowledge level for roasters, inexperienced coffee patrons, and merchants alike. It is usually considered as a easy marker of high quality, however there’s far rather more to it than that.

To actually perceive coffee density, you should recognize what makes coffees kind of dense, how they’re graded and categorised, and the way density impacts the method of roasting and the ultimate cup profile.

To study extra, I spoke to trade professionals from Kenya and Colombia. Read on to see what they informed me, and to study why coffee density is such an vital metric.

You can also like our article on the right way to roast laborious & mushy beans.

different types of coffee beans

What is bean density?

Density is the diploma of compactness of a substance. You calculate it by dividing the mass of an object by its quantity. In essence, coffee density is the load of a coffee bean proportional to its quantity.

Typically, denser beans may be recognized simply by taking a look at them. If the fissure line (the crack down the center of a bean) is near straight and solely barely open, the bean might be much less dense. Conversely, if the fissure line is crooked and closed, the bean might be extra dense.

For coffee professionals around the globe, bean density is recognised as an vital metric for grading and sorting inexperienced coffee by high quality. Harder, denser beans are typically prized by patrons around the globe, and producers usually obtain a better value for them in consequence.

green coffee beans

What makes coffee kind of dense?

Altitude is among the important elements that impacts the density of coffee beans. At increased altitudes coffee cherries mature and ripen extra slowly, leading to beans which are extra dense. Denser beans additionally comprise increased ranges of sugar, leading to extra advanced and sweeter cup profiles – which is why they’re extra fascinating.

The cherries mature for longer as a result of increased altitudes usually supply persistently cool temperatures all yr spherical. This is vital, because the arabica plant grows optimally at temperatures between 18 and 21°C (64 and 69°F). Outside of this vary, the fruit will mature too rapidly.

The ripening of coffee fruit is brought on by one thing referred to as the Krebs cycle. The course of converts acetate (which is derived from the carbohydrates, proteins, and fat within the cherry) into carbon dioxide. The Krebs cycle happens extra slowly at increased altitudes, which is why coffee cherries ripen extra slowly.

But altitude and temperature should not the one elements that play a task in bean density. Variety, rainfall, and even nutrient distribution all have an element to play.

Bourbon beans, for instance, are typically accepted as being comparatively dense, as are rarer and extra unique varieties like Geisha and Wush Wush. 

Peter Gakuo is a inexperienced coffee high quality management skilled based mostly in Kenya, and a employees author at Perfect Daily Grind. He explains that the distribution of vitamins inside a coffee plant may also have an effect on bean density. 

He says: “It’s quite common for coffee cherries on the finish of a department to be much less dense than coffee cherries nearer to the trunk, as a result of vitamins are centrally distributed by means of the center of the tree. They due to this fact have a tougher time reaching the top of the department.” 

Certain illnesses (equivalent to coffee berry illness, for example) and pests may also have an effect on the cherry maturation section of a coffee plant’s growth, and may trigger bean density to fall.

green coffee beans

Measuring coffee density

The important metric utilized by coffee professionals to grade and measure bean density is “hardness”. Bean hardness is usually break up into a couple of completely different classes, based mostly on a coffee’s altitude. However, the precise metrics and terminology used do differ from nation to nation.

For occasion, the phrases Soft Bean (SB) and Strictly Soft Bean (SSB) typically check with coffees grown at altitudes of beneath 1,200 m.a.s.l. or 4,000 ft. 

At these elevations, the much less secure temperatures and better oxygen ranges imply the cherries develop extra rapidly. The beans are due to this fact much less dense, and have a tendency to have a rounded flavour with much less sweetness and acidity.

After that, you may have Hard Bean (HB) or High Grown (HG) beans, that are coffees grown between 1,200 and 1,370 m.a.s.l. (round 4,000 to 4,500 ft).

At these altitudes, the upper elevation and corresponding low-oxygen environment causes the fruit to develop slowly, leading to tougher, denser beans with extra advanced and fascinating cup profiles.

Above 1,370 m.a.s.l., it begins to get slightly extra complicated, because the “greatest” elevation will really rely upon the area and origin in query. Ultimately, coffee grown at these sorts of heights may be known as Strictly Hard Bean (SHB) or Strictly High Grown (SHG), which is usually used as a designation for the highest-altitude coffees out there.

You may also establish bean density by wanting on the bodily traits of your coffee bean. The bean’s construction performs a key position in figuring out density; the extra ‘open’ its construction, the softer the bean, and the extra compact, the tougher the bean. 

roasting coffee

Roasting for bean density

Bean density can also be an vital parameter for roasters to maintain monitor of. If you roast beans of various sizes or density, they are going to develop in another way by means of the roast. For true consistency, it’s vital to separate them and roast them individually.

Peter says: “For pattern roasting and cupping functions, I might advocate finishing up inexperienced grading and separating completely different bean densities and bean sizes. The roasting course of requires uniformity.” 

Even when your beans are all largely uniform, it’s vital to do not forget that tougher and softer beans will behave in another way in the course of the roast. To adapt your profile accordingly, it’s best to have a look at two important elements: cost temperature and airflow.

Softer or much less dense beans, for instance, comprise extra air. This slows warmth switch all through the bean, which means that at a better cost (or beginning) temperature, you danger “scorching” the skin of the bean (often known as tipping). The resolution is usually to begin with a decrease cost temperature.

Conversely, for tougher or denser beans, begin at a better temperature to account for the shortage of air and the extra compact construction of the bean. 

Daniel Morales Espitia is an impartial coffee high quality advisor in Colombia. He notes that alongside cost temperature and airflow, density additionally impacts how sugars develop in the course of the roast. As such, he says that denser beans require extra of a deal with growth time.

He provides: “It’s additionally vital to think about the exterior surroundings of roasting, such because the altitude and temperature, as a result of these will have an effect on how the coffees react within the roaster.” 

Denser beans additionally usually have increased moisture ranges. Daniel says that it’s vital to account for this, and recommends roasting in smaller batches if you wish to maximise precision. 

Ultimately, preserving monitor of coffee density and understanding how beans of various density behave within the roaster will probably be essential when dialling in a roast profile for various coffees. Leveraging your information of density will ensure you can deliver the perfect out of every bean.

Proper storage can also be essential to preserving bean high quality. It’s vital to keep up fixed humidity ranges round inexperienced beans, as exterior temperature and humidity can have an effect on high quality.

Peter says: “Storing inexperienced beans very rigorously is essential, as a result of if they’re uncovered to excessive temperatures, coffees can dry out. If they’re uncovered to moisture, it could possibly additionally destroy the standard of the inexperienced bean and even trigger mould.”

light roast coffee beans

Bean density is a fancy subject, and simply considered one of a variety of metrics used to broadly assess high quality, nevertheless it’s an vital parameter for roasters to maintain monitor of.

By understanding how beans turn into kind of dense, what influences density, and what this implies for the roast, coffee roasters will have the ability to adapt their profile accordingly and be higher ready than ever to dial in every new lot they purchase.

Enjoyed this? You’ll take pleasure in our information to fluid mattress coffee roasters.

Photo credit: Nick Castellano, Pixabay

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