Determination of coffee characteristics. Influence of roasting technology and the caffeine content on the organoleptic properties.

Determination of coffee characteristics. Influence of roasting technology and the caffeine content on the organoleptic properties.

Caffeine is a chemical compound found in various plants such as coffee beans and cocoa, tea leaves, guarana berries and kola nut. It is normally added to a wide range of foods such as baked pastry, ice cream, desserts and cola-based drinks. Caffeine is also present in so-called energy drinks, as well as in some food supplements sold as slimming and sports performance stimulators, and in some drugs and cosmetics.

In human beings, caffeine consumption stimulates the central nervous system and, at moderate doses, increases mental lucidity, reducing drowsiness.

How much caffeine do we consume? The predominant source of caffeine for adults is coffee, which represents between 40% and 94% of the total intake.

The amount of caffeine in coffee beans changes if they are roasted. Toasting changes the properties of the coffee bean, first of all the concentration of caffeine. In raw coffee it is present in smaller quantities than the roasted one.

Coffee roasting consists of introducing the coffee beans into a specific machine where they are reach a very high temperature in a rather short time: temperature and timing generally depend on the type of coffee to be obtained.

There are, in particular, two distinct roasting methods. With the first one, also called "fluid bed", the beans are hit by a jet of hot air, at a temperature usually between 300 ° C and 400 ° C for a few minutes. The beans are then suspended for a short time in the roasting chamber. The resulting coffee is roasted mainly externally.

The second method, called "rotating drum", involves the use of a metal drum that continuously moves the beans. This method makes the entire roasting procedure uniform.

The "rotating drum" method is often preferred because it guarantees a more homogeneous roasting of the coffee, from which a more pleasant aroma also derives.

The project idea arises from the interaction with the owner of the local company “Torrefazione Iaquinta”, that produces a variety of coffee blends obtained from two varieties of coffee: Arabica and Robusta. The fourth and fifth year students took part in the production phase that leads from roasting to grinding and packaging, conducting a series of quantitative and qualitative analyses on the presence of caffeine in the various processing mixtures through the chemical analysis.

The learning model chosen to design the present activity is Inquiry-Based Laboratory (ILAB) (see Table 1), considered particularly suitable to enhance creativity in high school students. The project has been designed combining ILAB with CLIL methodology. The tasks and activities of the module focus on contents belonging to Non-Linguistic Subjects (Chemistry and Biochemistry), but at the same time aim at improving the students’ receptive and productive skills in English according to the descriptors of the Common European Framework of Reference.

PARTNERSHIPS INVOLVED IN THE PROJECT:

Table 2

RESOURCES NEEDED:

Technical equipment for HPLC, U.V/Vis. and FTIR spectrophotometry; samples of coffee (provided by Iaquinta Brothers), of different kinds and qualities; internet access to provide the students with opportunities to search for and evaluate information about global coffee production.