Instant Coffee: Remove Then Re-Add the Smell

One time-consuming way to make instant coffee from coffee—in a factory—involves removing most of the coffee aroma, then later adding it back to the coffee, so that later still—when someone makes the instant coffee in preparation for serving it to someone who will, still later still, drink  it, it smells like coffee. A new study looks at this smell manipulation:

Modeling Mass and Heat Transfer in Multiphase Coffee Aroma Extraction,” David Beverly, Estefanía Lopez-Quiroga, Robert Farr, John Melrose, Sian Henson, Serafim Bakalis, and Peter J. Fryer, Industrial and Engineering Chemical Research, vol. 59, 2020, pp. 11099−11112. The authors, at the University of Birmingham, UK, report:

Instant coffee manufacture involves the aqueous extraction of soluble coffee components followed by drying to form a soluble powder. Loss of volatile aroma compounds during concentration through evaporation can lower product quality. One method of retaining aroma is to steam-strip volatiles from the coffee and add them back to a concentrated coffee solution before the final drying stage. [We] present a multiscale model for aroma extraction describing (i) the release from the matrix, (ii) intraparticle diffusion, (iii) transfer into water and steam, and (iv) advection through the column mechanisms. Results revealed (i) the existence of three different types of compound behavior, (ii) how aroma physiochemistry determines the limiting kinetics of extraction, and (iii) that extraction for some aromas can be inhibited by the interaction with other coffee components.