Coffee Classification
('A classificação de café)







Measuring the Humidity
('Medir a umidade')

The classification begins always with the measurement of the moisture content. Just as in the tulha from Paulo, this should also ideally be between 11% and 12%. Even if the measured value deviates lightly, the Cooparaíso will buy the coffee, but then the purchase price drops significantly. But when these values deviate a lot, the coffee goes back to the farmer.

The moisture is determined by means of a ‘humidity measurement resistor’. In this, the resistance in the flow of the current is measured by means of an electrode with an exactly weighed sample amount.

Then Daniel weighs the sample amount for classification, and it is analysed to its minutest detail. The theory claims that always 300 gm of raw coffee should be examined. Practically everywhere, however, the classificadores take only 100 gm and extrapolate the results. This saves a lot of time and “In practice it has shown, that the measured values are nevertheless quite exact,” Daniel explains to me.










Sieving Size Groups
('Peneirar classes de tamanho')


The size of a coffee bean has no decisive influence on the quality of the flavor of the coffee, and yet bigger beans fetch a higher price. Besides the visual effect the theory assumes that the coffee beans from higher production regions grow slowly, have a higher ‘density’ and ultimately produce bigger, better beans. Daniel carries out the size classification with the help of a set of sieves (‘peneiras’). With it he sieves and separates the beans from “top to bottom” according to size and shape.

With three sieves having round sieve holes, he sieves the so-called mocha-coffee (‘café moca’); mocha-coffee, here, however, does not have the same meaning as that of the method of preparation of the Arabic, Turkish or Greek coffee! Mocha is Arabica-Coffee, featuring distinct characteristics: The beans are smaller, rounder and they have a lot of acidity. These features of the beans are attributed to the fact that the halves of the coffee cherry are not separated, but one single and smaller round bean is formed. These coffee beans are also called ‘peaberries’.

These sieved mocha coffee beans are sold almost exclusively in Japan, because the Japanese especially prefer these particular beans and therefore pay a good price for them. This meaning of the term mocha is common today only amongst the coffee experts, originally Mocha qualified as specific coffee type from Yemen, Daniel explains to me.

The markings of the sieve sizes are expressed in fractions of 1/64 inch units, whereby the number corresponds to the numerator of the fraction. Let’s take for example Sieve Size 19: This is thus 19/64 inch. When converted it means that the beans of the size class 19 cannot fall through a sieve with the hole size of 7.54 mm. The range of sieve sizes including conversion:

• Size 20:  0.31 inch  =  7.94 mm
• Size 19:  0.30 inch  =  7.54 mm
•  ...
• Size 09:  0.14 inch  =  3.57 mm
• Size 08:  0.13 inch  =  3.18 mm

The following official classification of the sieves considers not only the shape of the hole for normal, elongated Arabica beans, as well as the rounded shape for Mocha beans.

Elongated form, big: Elongated form, normal: Elongated form, small: Mocha form, big: Mocha form, normal: Mocha form, small

Sieve 17-20 Sieve 15, 16 Sieve 12-14 Sieve 12, 13 Sieve 10, 11 Sieve 08, 09

Evaluation of Defects
('Avaliação dos defeitos')

The raw coffee that has been delivered by the coffee farmers normally contains a reasonable amount of defective beans. Daniel and his crew must sort these by hand, evaluate them and make a projection of the whole delivery. These defects have varied influences on the later ‘cup quality’ and is therefore assessed differently through a point system.

Thus for e.g. broken beans though not nice, have less of an influence on the later flavor as for e.g. a small stone or a chunk of soil. Additional examples for possible defects are:

• Black, green, ‘burnt’ beans ('grãos pretos, verdes ardidos', so called “PVAs”, a definite term). These very typical defects provide a bitter coffee flavour. 
• Shells (small/big)
• Twigs (small/big)
• Broken Beans ('grãos quebrados')
• Small pebbles (small/big)
• ...
  

To know about and to avoid the causes for these and other defects is the task of the coffee planters, so that high quality coffee can be produced. Causes for the defects can be for example:

• Late harvest
• Longer contact with the earth
• Early harvest of the green fruits
• Genetic defects
• Long periods of dryness
• Lack of nutrition
• Defects due to plagues (for e.g. Coffee Berry insect, Bicho Mineiro etc.)
• False regulation of the husking machine
• Poor cleansing after the harvest and drying
• …

 


Categorization and Assessment System of Defects
('Categorização e sistema de avaliação de defeitos')


For a big pebble or twig 5 “Deficiency Points” are assigned, but for broken coffee pieces only 1 “Deficiency Point” is assigned. These points are added together and the sum then reveals the quality class, which matches the coffee at the end.

The quality class varies from 2 to 8. Within these classes is once again another very fine Point System that differentiates the categories according to the number of “Deficiency Points”. The best coffee is thus Class 2 (‘Type 2’) with 100 points: that is only 4 “Deficiency Points” with 300 gm raw coffee – a truly Gourmet Coffee. A “Type 8” is not recommended.

Mängel	Class	Points
4 - 11 12 - 25 26 - 44 46 - 79 86 - 153 160 - 340 360 +	Type 2 Type 3 Type 4 Type 5 Type 6 Type 7 Type 8	from +100 bis +055 from  +50 bis +005 from    0 bis -045 (Basis) from  -50 bis -095 from -100 bis -145 from -150 bis -195 -200