OUR BLOG

Production of speciality coffee needs a proper plan for harvesting the coffee cherries as it gives good economic returns for producers. The time of harvest varies in different places. According to the processing method to be implemented, harvesting the coffee cherries without causing damage to the tree is an important task. In most of the coffee-producing countries, coffee is harvested once per year. As the coffee cherries mature, the coffee fruit contains suitable chemical compositions which lead the fruit to the best quality. The coffee fruit also contains volatile compounds that are responsible for the aroma and flavour properties of the coffee. These compounds are present at a very low amount at the early stage of the coffee cherry, but later on, it increases as the coffee transformed to the maturity stage. There are two strategies (strip and selective picking) for harvesting the coffee cherries, which are widely used.

1. Strip picking

This strategy is usually done by machinery or by hand. The whole coffee cherries are harvested at one time. The harvested coffee may not achieve the desired quality due to the mixture of underripen or overripen coffee cherries. In order to use machinery for harvesting the coffee cherry, the following factors are critically important such as the topography, inclination, spacing, alignment, and the height of the plant. Considering these factors, the producer should choose the right harvesting system that suits their crop.

2. Selective picking

The major challenges in the coffee sector are obtaining uniform maturity, and at the same time, it is the procedure to provide consistent quality coffee. It is important to note that in most flowering plants the climatic condition during the growing period can change the number of flowering plants which affect the maturation uniformity. In this harvesting system, only the ripened coffee cherries are harvested selectively by hand from the whole tree or branches. The harvested coffee meets the standards due to the uniformity of the cherries. This strategy needs several picking rounds and is labour-intensive. Considering the advantage and disadvantages of both harvesting strategies is the key for coffee growers. The coffee cherry has different layers that surround the beans, such as skin, pulp, mucilage, parchment, silver skin, and finally, the coffee beans in figure below (Coffee Cherry Anatomy).

The pulp and mucilage are rich in nutrients, and its chemical compositions are presented in Tables below. These days the coffee pulps are being used for making a coffee wine by fermenting the coffee pulp. So far, there are two patents already registered in Korea. The ripe coffee cherries have colour ranges from bright red to deep red and yellow, depending on the plant variety and for ripe cherries.

Components	%
Ether extract	0.48
Crude extract	21.4
Crude protein	10.1
Ash	1.5
Nitrogen-free extract	31.3
Tannins	7.8
Pectin substance	6.5
Non-reducing sugars	2
Reducing sugars	12.4
Chlorogenic acid	2.6
Caffeine	2.3
Total caffeic acid	1.6

Components	Concentration (g/L)
Glucose	35.65
Galactose	37.67
Lactose	1.06
Proteins	0.119
Syringaldehyde	0.61

 

Minerals	(mg/L)
Sulphur	30.19
Calcium	37.08
Potassium	239.8
Magnesium	10.05
Phosphorus	41.55
Sodium	7.18
Iron	0.65
Copper	2.45
Zinc	0.14
Manganese	0.07
Boron	0.16
Barium	0.02
Arsenic	0.47
Lithium	0.01
Silicon	1.58
Strontium	0.07

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