Recovery of bioactive compounds from artichoke brines by nanofiltration

• The recovery of bioactive compounds from artichoke brines was investigated.
• The performance of different nanofiltration membranes was evaluated.
• 200 Da membranes showed best results in terms of recovery of phenolic compounds.
• The NF permeate is a salt solution free from phenolics reusable in the processing cycle.
• A process design was proposed for producing fractions of nutraceutical interest.

In this work a membrane-based process for the fractionation of artichoke brines was investigated in order to separate flavonoids and caffeoylquinic acids from salt compounds. Therefore, the performance of different spiral-wound nanofiltration (NF) membranes in the treatment of clarified artichoke brines was evaluated in terms of productivity and selectivity towards bioactive compounds in selected operating conditions. Membranes with different polymeric material (polyethersulphone, polyammide) and molecular weight cut-off (MWCO) (from 200 to 1000 Da) were tested. NF membranes of 200 Da produced better results in terms of recovery and concentration of compounds of interest. A better separation of salt compounds from caffeoylquinic acid derivatives was reached by using Filmtec-Dow NF 200 and Desal DL membranes. For these membranes a low rejection towards dry residue (between 14% and 18%) was observed, while rejections towards total caffeoylquinic acids, flavonoids and cynarin were higher than 92%.According to the obtained results the NF permeate, enriched in salt compounds, can be reused in the working cycle for the preparation of new acidulated brines through the adjustment of the standard salt concentration; the concentrated stream, enriched in phenolic compounds, is a good source of possible ingredients to functionalize foodstuffs.