Start the day with the Alutronic Powerbloc PO 100-100
Student produces instant coffee using adsorption drying
Using an Alutronic Powerbloc PO 100-100 the student Pascal Koschwitz from the Technical University Berlin succeeded as part of his master thesis in winter 2020 in drying coffee and producing crystalline, good-tasting soluble coffee (see Figure 1)
The water-attracting zeolite balls in the Powerbloc remove the water from the freshly brewed coffee under vacuum (see Figure 2 and Figure 3). The heat generated by the adsorption oft he water onto the zeolite is transferred from the Powerbloc to the bowl containing the brewed coffee and thus provides the heat needed to evaporate the water.
The advantage of this process is the low evaporation temperature of slightly more than 0°C, which allows the dried coffee to retain its aromas and taste.
Figure 1: Comparison of instant coffee types. Left: Conventional spray-dried coffee. Middle: Conventional freeze-dried coffee. Right: Innovative adsorption-dried coffee.
Figure2: Top view of the test apparatus. The Petri dish with the freshly brewed coffee to be dried is placed on the Powerbloc filled with zeolite balls. The black cables are part of the temperature measurement.
Figure3: Principle of adsorptive drying. The mass flow of the evaporating water M ̇_(H_2 O)^V adsorbs to the zeolite (black dots in the grey aluminium pin cooler). This releases the adsorption heat Q ̇_Ads. The heat is transferred by heat conduction Q ̇_Kond from the powerbloc to the bowl of coffee (brown area) for further evaporation of the water.