Foam mat drying of coffee aqueous extract: Foam process optimization, drying kinetics, energy consumption, and energy efficiency analysis

Abstract

The instant coffee consumption has been growing mainly due to consumer's search for quick-prep foods. Foam mat drying (FMD) is an innovative technique that promises energy savings for industries. The instant coffee production by FMD was evaluated by identifying the best foaming conditions and analyzing the kinetics and energy aspects of drying. The effect of albumin concentration (3.5–6.5 % w/V), whipping time (2.5–12.5 min) and stand mixer rotation speed (975.67–1066.67 rpm) on properties of foamed coffee extract (FCE) was investigated using a desirability function. FCE at optimal condition (5.05% w/V, 6.5 min and 1066.67 rpm) was dried in oven (50–90 °C). Increasing the drying air temperature reduced the process time due to the increase in the drying rate and resulted in reductions in specific energy consumption and CO2 emissions. Energy efficiency was reduced over time. These results show that FMD is a promising technique to produce instant coffee.