Coffee beans roasting are an important process in determination of the flavor of the coffee. It is the transformation of green coffee beans’ chemical and physical properties to form coffee products which are roasted.
Roasting helps in bringing the aroma out which is locked inside the coffee beans which are green. The beans ‘greenness helps the coffee bean in retaining its quality and taste.
Chemical changes are caused by roasting as the beans are rapidly brought to temperatures which are very high. On reaching the peak, they are cooled quickly in bringing the process into a stop. Coffee beans which have been roasted weigh lesser since the moisture has been roasted out. On biting, they are crunchy and can be grounded or brewed. Roasting of the coffee beans is an art and also a science. For one to become an expert in coffee beans roasting, he/she needs to undergo a training to be able to read the coffee beans and making decisions with timing in split-second.
The process of coffee beans roasting
Roasting of the coffee beans is a process whereby the heat turns coffee into dark brown beans which are fragrant. The whole process consists of sorting-roasting-cooling, grinding and also packaginkg.Bags carrying the green coffee beans are opened by a machine and are dumped into a hopper which screens in removal of debris.Weghing of the beans then takes place and they are transferred to the conveyors which are pneumatic into hoppers for storage.
The coffee beans are then lead into the roaster where the real process begins.
It starts with an endothermic process where the green beans dry slowly to develop a color which is yellow a toast like smell. After that, the first crack at 205 degree Celsius occurs where the coffee bean enlarges in size and turning its color to light brown having a 5% weight.
The temperature then rises from 205 degree Celsius to 220 degree Celsius and the color turns from light brown to brown which is medium to gain a weight loss of 13 %.The chemical process that results from here is a pyrolysis process characterized by the chemical composition change of the beans as they release carbon IV oxide.
A short period, which is endothermic, is followed by the second crack which occurs at between 225 degree Celsius sand 230 degree Celsius when the roaster color is fully defined i.e. medium dark brown. The coffee beans heat themselves and they require the roaster heat to be adjusted at the source.
Potentials which are espresso are maximized during roasting when maximizing the sweetness of the coffee and minimization of the acidity and bitterness of the coffee bean. Sugars contained in the coffee bean are caramelized at between 170 degree Celsius to 200 degree celcius.Sucrose on the coffee has a direct relationship with coffee’s dark color.
Coffee beans which are premier like the Hawaiian Kona are lightly roasted in preservation of coffee flavor which is innate. This implies that the rate of cooling of the coffee beans and the method used can affect the flavor of the coffee.
In the coffee market, roasts of coffee are described by .names like, French roast coffee or Full City Roast Coffee. They say that the best choice is the Full City Roast Coffee.
In the past, roasting of the coffee beans was done by the use of a frying pan which is dry and a medium heat applied. As the stirring continuous, the heat is monitored to prevent the coffee beans from burning .The roasting takes 15 minutes. After the roasting process, the coffee beans are placed on a plate and a towel placed on to it for excess oil removal.Cofee which is the strongest is obtained from prolonging the roasting process for more 5-7 minutes.
Equipment used in coffee roasting depend on the roaster’s ambitions. Screws which are gigantic with a drum which is rotating are used for roasting of coffee beans commercially. The screws help the coffee beans to move downwards into the drum. As the coffee beans reach the end of the drum, it becomes roasted and is cooled by water or air. Temperatures are automatically controlled.
A specialty roaster has a batch roaster that rotates coffee in batches at a rather time. Drum and hot air machine is a roasting machine whose rotating drums are horizontal to enable green coffee beans to be tumbled in heat. Heat source can be gas, electricity or wood. Heat source is placed under the drum.