*3.5.2 Medium roast*

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

**Figure 5.** *The most common types of roasting conditions (A, light roast; B, medium roast; C, medium-dark roast; D, dark roast).*

#### *3.5.3 Medium-dark roast*

Medium-dark roasted coffee has a dark brown colour, and the surface of roasted beans developed oils. It is characterised by fully bodied deep flavoured and little spicy notes. It has low caffeine content. This roasting condition is attained when the internal temperature of the coffee bean reached nearly 229°C (**Figure 5C**). Overall, roasting coffee in medium to dark conditions causes an increase in ketones, esters/ lactones, aldehydes, aliphatic acids, and aromatic acids, but a reduction in caffeine content is observed [67–69].

of green and/or roasted coffee beans. Each step of the post-harvest activities can

cause a significant quality loss and lead to a lower market price.

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

The authors declare no conflict of interest.

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

**Conflicts of interest**

**Author details**

Republic of Korea

**71**

Mesfin Haile<sup>1</sup> and Won Hee Kang1,2\*

Chuncheon, Republic of Korea

provided the original work is properly cited.

1 Department of Horticulture, Kangwon National University, Chuncheon,

2 Convergence Program of Coffee Science, Kangwon National University,

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: whkang@kangwon.ac.kr

#### *3.5.4 Dark roast*

It has nearly a dark colour and produced oils on the surface of the coffee beans. The darker the coffee beans, the less the acidity. It is also characterised by very low caffeine content with heavy mouthfeel, strong flavour, bitter, and burnt or smoky notes. When the coffee is roasted in the dark condition, the internal temperature of the coffee beans reached approximately 246°C (**Figure 5D**).

Grinding is the next step after roasting. In this step, the coffee beans are crushed and changed into powder at different particle size. It is done using a grinding machine (electrical) or using mortar. However, to achieve a uniform ground size, an electrical grinder is the best choice. Blenders can also be used for grinding coffee beans, and the larger particle size and the broadest distributions can be seen while blending the coffee beans [70]. The grinding size is usually measured by using sieve analysis. According to the types of coffee to be prepared, the particle size or grinding particle is the most important. There are many types of grinder with the adjuster to regulate the particle size of coffee grounds. During grinding the important volatile compounds are dispersed into the surroundings from the powdered coffee, so it must be executed right before the intended brewing (1–12 min after grinding) to maintain the volatile compounds [71, 72].

The coffee brewing and extraction methods differ according to the personal preference, the culture, geographical, and social and financial factors. All these brewing and extraction methods of coffee vary depending on the time of extraction, the pressure, the brewing tool, the temperature of the water, and the extraction amounts. The brewing water quality (electrical conductivity) is another important aspect for maintaining the original coffee flavour and test. The size of the coffee ground determines the rate and the total amount of extraction. If the coffee is too fine (for example super-fine) extraction will not happen as water cannot pass through, and if it is too course the grinds will be under-extracted. It depends on the coffee ground size, the coffee brewing methods also vary. Mostly for French press coffee, a coarse coffee ground is preferred, whereas the fine ground coffee is used to make the espresso coffee.
