In this article, we will focus on the physical size of the green grain and its effect on two components:
Taste
roasting
In every country that supplies coffee beans for export, the beans go through a sorting stage. There are cellular sieves of different diameters that allow you to separate the coffee beans by size. Sieving - selection of coffee beans for size and shape. This is often one of the last stages of green grain processing before it is packaged and sent for export.
Sorting is performed by large machines representing multi-level tables placed one above the other with a slight downward slope. When the machine is turned on, the coffee is poured from above, and under the influence of gravity, the grains pass through the sieve. Each sieve is equipped with metal sheets with holes of a certain diameter. Usually bags are kept under the machine to catch the coffee flow. Multiple passes through the device can improve calibration accuracy.
Sieve openings are measured in inches. A screen is equal to 1/64 inch or 0.04 cm. You can convert the display to centimeters using the formula: divide the grain display by 1/64 and multiply by 2.54. So 16 frets equals 0.64 cm.
This measurement system has been adopted by most countries. The only difference is that the name of the display range is different for exporting countries.
Curiously, Brazil uses the name Strictly Soft, which does not mean coffee grown at high altitudes or physically strong. This designation is an indication of the highest degree. East Africa and all of India still use the British letter designation grading system. The terms SHB and SHG in Central America refer to beans grown in the mountains. Colombia has long been known for its coffees called Supremo and Excelso. As a result, there is no universal classification system for green coffee beans.
Some people traditionally assume that taste depends on size. This is far from the case, because many parameters affect the taste: genetics, terroir, processing, etc. and there is absolutely no point in relating it. But many companies have a different perspective. It can be seen that Kenya AA is priced significantly higher in the market than Kenya AB. This example is the result of the “plus-size mentality” dictated by the International Trade Center (ITC) and the International Coffee Organization (ICO). These organizations argue that size-based classification is the right approach, as coffee at higher altitudes becomes denser and larger than coffee produced at lower altitudes. Similarly, coffee develops more slowly at higher altitudes and generally has better flavor profiles. After all,
In the above examples, we omitted Ethiopia, one of the most important coffee producers. In this country, on the contrary, the screen is a secondary factor in the choice of coffee beans - this is one of the features of Ethiopia, where coffee is not sorted by size. Attention is paid to the most important parameters such as grain density, number of defects and processing method. All parameters correspond to a certain degree, and there are only 8 of them. For example, grades 1 and 2 - premium coffee, mostly washed processing, but not necessarily - there is also a small number of high-grade natural processing. Grades 3 to 8 are natural processing, characterized by a greater number of defects. Coffee below the 6th grade is not exported and can only be used in the domestic market.
Q-graders are engaged in the professional evaluation of coffee. In this case, the size of the grains in the test sample is evaluated regardless of the taste assessment. Them. There is no relationship between the size and taste of coffee in the grading system.
In the example of the batches, you will show that the physical size of the grain does not directly affect the taste.
We have a very unusual coffee in our product range. This is very much from Wagner Ferrero - Pantano Farm located in the Cerrado region, Brazil.
The Ibairi variety is experimental, brought from Hawaii to Brazil, is characterized by extremely small grain size and is rarely grown due to low yield, processing and roasting difficulties due to the presence of obvious defects remaining in the grain, as conventional sorting methods do not allow them to be selected purely because of the characteristics of the screen. does not give. However, it often gets high marks from professionals for its unique flavor properties.
At the same time, many things related to good trade, for example, can be very uniform and beautiful in size, but do not stand out with any particular bouquet.
Size and Roasting
As mentioned at the beginning of the article, sieving is the selection of the grains according to their size. This is a very important processing process because the grains of different sieves conduct heat differently and are roasted differently as a result. Because of the different contact areas of the beans with the roasting drum (mainly this applies to conduction roasters), choosing a roasting profile will be problematic. Therefore, if the grains are sorted by size, the taste will be positive.
A more even frying will be achieved. But grain size also affects convection, the smaller the grains, the denser they are to each other and the more difficult it is for air to pass through and conduct heat and moisture. With the proper organization of working with grain, these nuances are quite manageable. Roasting profile is selected for each batch, taking into account its characteristics.