NAMS 2002 Workshop - ICOM 2008

Pervaporation and Vapor Permeation III – 2
Friday July 18, 3:00 PM-3:30 PM, Kaua’i
Monitoring and Modelling of Aroma Recovery from Fermentation Media
Using Pervaporation and Fractionated Condensation
C. Brazinha (Speaker), Universidade Nova de Lisboa, Caparica, Portugal -
carla.brazinha@dq.fct.unl.pt
O. Teodoro, Universidade Nova de Lisboa, Caparica, Portugal
J. Crespo, Universidade Nova de Lisboa, Caparica, Portugal
Introduction
Organophilic pervaporation has a high potential for aroma recovery from dilute
aqueous solutions because it involves a low energy input when compared with
other separation processes such as distillation. Also, it operates at mild
conditions allowing a direct recovery of aroma compounds from fermentation
processes or biological complex media.
Mass spectrometry (MS) proves to be a powerful analytical tool for studying the
recovery and fractionation of aromas using pervaporation-condensation systems
because it allows for on-line monitoring of the concentration of each vapour
present in the permeate stream. Due to its high sensitivity and precision, MS is
particularly suitable for on-line monitoring of aromas present in trace
concentrations. It also enables transient studies and reduces experimental
workload significantly when compared with conventional gas chromatography
analysis.
Previous work proved that MS can successfully on-line monitor pervaporation
processes under variable upstream conditions [1]. The present work aims to
extend the use of this technique for processes with variable temperature of
condensation and downstream pressure.
Aroma recovery both from fermentation media (e.g. for valorisation of aromas as
by-products of the bio-ethanol production) and also from other biological media is
not an easy task since aromas are usually dilute in a complex mixture (aroma
profile). Fractionation of aromas is important to consider when we are interested
in a particular aroma or group of aroma compounds. Aiming at defining suitable
strategies for recovery and fractionation of aromas, in order to obtain pre-defined
condensates, a mathematical model was developed and experimentally
validated. This model allows for optimisation of the temperature in first
condenser, in a pervaporation process using in-series condensation. This model
also applies successfully to media where ethanol and dissolved gases (carbon
dioxide) are present.