Résumé
This work investigated the coupling of microfiltration (MF) and nanofiltration (NF) to concentrate the volatile compounds in a raspberry hydroalcoholic extract. Enzymatic treatment increased the MF permeate flux by 30%-50%. The highest MF permeate flux was above 50 kg·h À1 ·m À2 at a mass reduction ratio of 5. MF allowed efficient clarification of the extract without significant retention of aroma compounds. Among the NF membranes tested using the MF permeate as feed, one membrane was clearly more effective in concentrating the extract in terms of flux (19 kg·h À1 ·m À2 at 35 bar), retention of aroma compounds (average retention of 85%), phenolic compounds (61%) and dry matter (90%). Three other membranes were of interest for the fractionation of volatiles in both permeate and retentate but with a lower permeate flux. Finally, one membrane retained few aroma compounds but showed 70% dry matter retention, making it a promising method for aroma purification versus dry matter content in the permeate.