**3.3 Hulling and sorting**

(10–12%) and to separate the parchment from the coffee beans easily. Sufficient drying is a crucial step to avoid the developments of moulds, which leads to significant losses and affects coffee quality. The drying methods were significantly affected the amount of low molecular weight (LMW) carbohydrates that present in the green coffee beans [47]. Several researchers reported the responses of coffee to various drying processes. The coffee cherry kinetics and drying characteristics under different drying temperature (40, 50, and 60°C) were investigated [47]. The effect of drying and storage conditions on the quality of washed and natural coffee was evaluated by Coradi et al. [48]. This research was focused on the relevance of suitable drying along with sufficient storage conditions to maintain the coffee quality. There are two ways for drying the coffee, such as natural drying using

This drying method is the most common, widely practised in many countries and the cheapest way of drying the parchment coffee or the whole coffee cherry. This activity is highly dependent on climatic conditions and seasons. The removal of the mucilage and pulps at an early stage in wet-processing reduces the time needed for drying. There are different kinds of sun-drying methods. Coffee is typically dried on large patios made of cement or asphalt concrete with a 0.5–1% slope to drain the water. Using the natural sunlight, drying of coffee takes 7–15 days for parchment coffee and 12–21 days for coffee cherries in patios. This duration varies depending on the weather conditions. The parchment coffee needs special attention than cherries to reduce physical damage (cracking). Raking is required to allow the coffee to dry uniformly, but it should be carried out carefully. In some tropical countries, during the hottest hours of the day, covering sheets used to avoid the

sunlight and mechanical drier.

*Elephant dung coffee preparation in Nepal.*

*Coffee - Production and Research*

*3.2.1 Sun (natural) drying*

**66**

**Figure 4.**

Hulling is the next step after drying. The dried coffee cherries (dry-processed) or parchment coffee (wet-processed) hulled to remove the covers and get the coffee beans out of it. Once the coffee bean reaches this stage, it means all the essential quality, such as colour and moisture content, has already been achieved. Hulling is done by using different hulling machines, or locally on a small-scale farm, wooden mortar and pestle used to separate the coffee beans from the parchment or dried coffee cherries. Commonly there are two kinds of coffee hulling machines. One is which rubbed off the parchment by friction, and this might create heat. The second type is just cut the parchment and stripped off. It is essential to take care of the coffee beans and avoid physical damage even not to heat the beans during hulling because it affects the colour and taste of the coffee. The last layer that encloses the coffee beans is thin silver skin, and this may be removed or may not be removed during the hulling process. If the coffee beans'silver skin is not separated during hulling; it needs a machine called polishers to separate it and get the green coffee beans. Finally, the green coffee beans are ready to be cleaned and sorted according to colour, size, and density [52].

The hulled coffee beans then undergo sorting processes, which is done by machine and hand. Hand sorting is most widely used, and it requires intensive labour for sorting the coffee beans based on size, colour, and density. The samesize and larger coffee beans get a premium price in the market, and a high percentage of defect may lead to a lower grade, and the price is also low [53]. Sorting is a crucial step because it affects the roasting condition. Uniform size coffee beans should be roasted to achieve uniform roasted beans. Sieve machines are used to screen the coffee beans according to their size. The sieving principle is applied in the sorting machine, which is using a big vibrating flatbed [54]. There are different kinds of machines used to sort coffee beans. Electronic devices are also used to separate the coffee beans by their colours. However, this is not always sufficient to detect and separate the good and bad coffee beans. After sorting is properly done, the coffee beans are then packed with the right packaging materials and transferred to the storage house.

### **3.4 Storage**

Right after the coffee beans are graded, they have to be kept in a storage house until they shipped and sold in the market. The temperature and relative humidity of the storehouse should be controlled to maintain the coffee quality without losing its intrinsic sensorial characteristics and physical and chemical properties and to store for a longer time. Afonso [55] reported that as the storage relative humidity is higher for an extended time, it decreases the compositions of reducing sugars in green coffee beans. Several research reports are available about the effects of storage conditions on the sensorial quality of coffee beans. He also mentioned that the 60% relative humidity with longer storage causes to cellular degradation and leads to oil leaking, which also contributes to the chemical compositions of green coffee beans. When the storage duration is prolonged, the oil becomes more acidic, and it reduced the quality of the product [54].

technology used for coffee roasting. There are different kinds of roasting condi-

The lightly roasted coffee developed light brown colour, and it is preferred to make a coffee with a mild body. It has light fragrant, floral or fruity coffee notes. In this roasting condition, the coffee beans should not develop oil on their surface. It is also characterised with pronounced acidity and high caffeine content. During light roasting, the internal temperature of the coffee bean reached approximately 204°C

Medium roasted coffee developed medium brown colour, and the surface of the coffee beans should not have oils. It is characterised by balanced aroma flavour and acidity. Traditionally this is the most preferred roasting condition. It has medium caffeine content. To achieve this roasting condition, the internal temperature of the

*The most common types of roasting conditions (A, light roast; B, medium roast; C, medium-dark roast; D, dark*

tions. The most common roasting types are discussed below.

*DOI: http://dx.doi.org/10.5772/intechopen.89224*

*The Harvest and Post-Harvest Management Practices' Impact on Coffee Quality*

coffee beans reached approximately 215°C (**Figure 5B**).

*3.5.1 Light roast*

(**Figure 5A**).

**Figure 5.**

*roast).*

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*3.5.2 Medium roast*
