Recuperação dos componentes do aroma de café por pervaporação

Abstract

At present, Brazil is the first world coffee producer sharing 30% of the international producer market and occupies second rank of the consumer market. Pervaporation is a membrane separation process where liquid mixtures are fractionated due to partial vaporization of its components through a dense selective membrane. Pervaporation is more advantageous than traditional processes, such as solvent or vapour extractions, due to the possibility of operating without solvents and at moderate temperatures, thus avoiding the degradation of termosensible compounds and reducing energy consumption costs. This process can be used to the recovery and concentration of volatile components from beverage aroma. This work had as objective to study the pervaporation of coffee beverage in order to obtain a natural concentrated extract, using two different flat sheet membranes, polydimethylsiloxane (PDMS) and ethylene propylene diene terpoly-mer (EPDM), at three temperatures (25ºC, 35ºC and 45ºC). Total permeate flux and the enrichment factor of some compounds were calculated for evaluating the process performance. The aromatic profile of the coffee beverage was determined by gas chromatography and mass spectrometry (GC-MS). Two extraction methods (solid phase micro extraction and solvent extraction) were used before chromatographic analysis. PDMS membrane exhibited a higher permeate flux when compared to EPDM membrane. Increasing the temperature resulted in a positive effect on the permeate flux, according to the Arrhenius equation. The EPDM membrane presented higher enrichment factors, being more selective for extraction of the aroma compounds. Through GC-MS there were identified 69 components of the coffee beverage. Experimental results showed that pervaporation process is a membrane technology able to recover and to concentrate coffee beverage aroma and that EPDM membrane exhibits a higher performance than PDMS membrane during such a process.