Roasted coffee | Coffee roasting process - רשת בתי קפה לנדוור

The Roasting Process

When talking about coffee flavors the roasting process is of high relevance.

Numerous and elaborate processes occur prior to our taste buds stepping in when tasting high-quality coffee. During the roasting process the raw (and green looking) coffee beans transform both chemically and physically; they shed about 20% of their mass whereas they increase in volume. The chemical reactions that occur within the bean during the roasting process is what lastly grants it its unique and popular taste.

An overview of the roasting process:

Following harvest in one of many different climate zones around the globe, the raw coffee beans are transported in sacks of about 60-70 kg each. Upon delivery at the roastery they get stored in large containers after an initial filtering and cleaning, ensuring the removal of dust particles and other forms of dirt. From the containers they are then moved into large ovens where they will be dried prior to being roasted.

During the first stages of roasting the beans absorb the heat that is responsible for the first chemical shift they undergo (the chemical reaction that grants them their flavor and aroma). Toward the middle of the roasting process the heat inside the oven is turned down as the beans start to radiate the heat they had absorbed. By the end of the process the oven has almost fully cooled down. This phase plays a crucial role in the formation of the final product. When the coffee beans arrive to the desired temperature at last (depending on the nature of the final product, be it turkish coffee, espresso etc.) they are transported onto a cooling belt where their temperature will sink. From the carousel they make their way onward to a sealed container where they will sit for about 48 hours in order for all chemical reactions to come to an end. In the field of roasting two main methods are applied in accordance with the technical equipment at hand:

1. Conduction Roasting System - The traditional method in which the coffee beans are inserted into a hybrid conduction drum, which is placed above a heat-radiating mechanism. The heat transmitting through the body of the drum onto the coffee beans is evenly spread by the rotation mechanism of the drum.

2. Convection Roasting Method - A system in which air that is heated to high temperatures is inserted with great pressure into a rotating drum holding the coffee beans. This system allows for more control over the roasting profile, the rotation speed and the air pressure inserted into the apparatus. This system also allows for higher quantities to be roasted in shorter amounts of time without losing the precision and homogenous final product. Each one of these methods allows for different roasting variations:

• Roasting each type of bean separately and then combining it into a new blend. • Roasting different types of coffee together.

Each variation has plus and minuses, yet both are equally popular. Roasting each type separately guarantees optimal roasting as we apply different roasting profiles for each coffee bean sort according to its traits (size, robustness and pH levels). After individually roasting the different coffee bean types a new blend is created. A blend which is the sum of its parts. When roasting different types together a more homogenous blend emerges. In this process every type leaves its mark on the overall taste of the blend and new characteristics are formed. Analogues to cooking, where each ingredient is handled separately and is pieced together to form a dish, and unlike the making of a stew where all the ingredients are cooked together and create a new taste by effecting each other’s flavor. A fact worthy of mentioning is the significant distinction to be made between coffee types from the Robusta family and the Arabica, whereas even within these families roasting profiles may vary.

This article was written by Oren Marimi - head of Landwer’s Roastery.