(344e) A Non-Thermal Process to Extract Aroma Compounds from Coffee Using Membranes

This work deals with a non-thermal process for extraction of aroma compounds from coffee solutions to prevent thermal degradation. Conventional soluble coffee processing involves extraction of soluble components from ground coffee, followed by thermal evaporation of water and drying of the concentrated extract. Unfortunately, the concentration step not only removes water, some coffee aromas are lost as well. While such techniques as gas stripping may be used to recover aromas prior to evaporation, but aroma components with high volatilities cannot be recovered, resulting in an undesired alteration in the flavor profile. Here we present a new processing concept to reduce thermal exposure of the coffee extract and its aromas based on an integrated process of nanofiltration (to concentrate coffee solubles without the use of heat) and low-temperature pervaporation (to recover aromas from the nanofiltration permeate). Nanofiltration is preferred over reverse osmosis for concentrating coffee extracts because of its higher flux, lower propensity for fouling, and its ability to attain a higher extract concentration. Since nanofiltration allows both water and aroma to permeate through the membrane, pervaporation is used to recover the aromas from the nanofiltrated coffee extract. Both continuous and batch pervaporation of multicomponent aroma solutions were carried out using organophilic membranes, and all the representative flavor compounds tested were shown to be preferentially permeable through the membranes. It was also shown that the membranes can be tailored to yield a balanced flavor profile in the aroma stream recovered.