COFFEE PRODUCTION - SECONDARY PROCESSING
Coffee is mainly processed in two ways – Dry Processing and Wet Processing. The beans obtained are packed and stored in jute bags for further processing, also known as Secondary Processing.
These final steps which are carried out at curing works involve removal of the husk or the parchment from the beans to obtain green coffee beans. These coffee beans are again packed and stored.
Let’s look at how coffee is further processed after long periods of drying.
Sample Testing – The coffee received in bags is tested in samples to determine its quality, percentage of different grades, check for defective beans and also assess moisture content.
Re-drying – The moisture content of the dried coffee should be 12%. However, if it is under dried, it should dried again in open areas on concrete floors to the prescribed moisture level that facilitates easy milling and increases the shelf life of coffee.
Cleaning –The coffee is passed through screens to separate it from twigs, leaves, etc. Then it is rolled on conveyor belts where a continuous stream of air flows blowing the coffee beans to one side and heavy particles like stones, pebbles to the other side.
Milling – This is the process of removing the dried husk or the parchment from the processed coffee.
The parchment coffee, obtained from the wet processing of coffee, has the parchment and the silver skin. The parchment is removed by peeling and the silver skin by polishing. This gives a clean appearance and also limits the amount of chaff produced while roasting the coffee.
The cherry coffee, on the other hand, is processed in a method known as hulling. The cherries are directed into a huller where the dried husk is removed.
Winnowing – This is done to remove the all the bits of pulp and skin from the coffee. The coffee that is winnowed is called bulk coffee.
Grading – The bulk coffee is graded on the basis of size, shape and density. Various machines are used to grade the coffee like drum graders, PB (peaberry) band separators and gravity separators.
DID YOU KNOW?
A peaberry (PB) is a coffee berry containing one seed instead of two formed when one ovule is non-fertilized or subsequently aborted. Such beans are valued for their fine flavour.
Sorting - The beans are further sorted on the basis of colour to separate the defective beans like blacks, browns, greens, discoloured beans using electronic colour sorters.
Packing – The coffee which is of high quality and also produces a uniform cup is bulked in small lots either manually or by using machines. Coffee is packed in jute bags or any material that does not affect the quality of coffee. The standard size for packing green coffee in a bag is 60kg in India.
Storing – Coffee is stored in warehouses built under specified industry standards. Care has to be taken to protect the coffee from insects, rodents and humidity. Coffee that is stored for prolonged periods without controlling the conditions may get affected and impart undesirable flavours. The area should be kept clean and dry with proper ventilation and air circulation.
Small lots are roasted and ground. The lots are cupped to determine the taste, aroma, acidity, body and flavour of the coffee.
Coffee exhibits 800 different aromas and flavours that can be experienced while roasting and tasting. Like what you just read? Welcome to the world of coffee! Do read about roasting in our next blog.