Green recovery of bioactive phenolics and nutrients from Murta (Ugni molinae Turcz) fruit through nanofiltration, and their identification by tandem mass spectrometry

• Nanofiltration processing recovers bioactive molecules from Murta fruit. • Murta fruit phenolics are highly concentrated by the used nanofiltration membranes. • Among the membranes tested, the DL one presents the most important permeate flux. • The permeates obtained contain attractive mixtures of phenolics and amino acids. • UHPLC-ESI/MS/MS is a useful technique to quantify metabolites during nanofiltration. Bioactive molecules can be selectively recovered by membrane technology, promising efficient alternatives to traditional methodologies such as column chromatography, liquid-liquid and solid-liquid extractions. Murta fruit was nanofiltered to recover primary and secondary metabolites involved in human physiology. Three membranes with different molecular weight cut-offs (MWCOs) were tested sequentially and separately (DL (150∼300 Da), NFW (300∼500 Da), and NDX (500∼700 Da). ESI/MS/MS identified several metabolites composing the Murta fruit, which were well fractionated according to their specific molecular weights (MWs). For several phenolics, the membranes presented retention percentages (RPs) of 100 %. Particularly, catechin (MW: 290.27 Da) showed negative RPs (-57.10 ± 23.50 % (DL), -11.91 ± 8.77 % (NFW), -2528.39 ± 1126.13 % (NDX)). The quantification of phenolics was done using UHPLC-ESI/MS/MS. Certain amino acids (MWs 100∼300 Da (cysteine, aspartic acid, serine, proline, valine, phenylalanine, lysine, and glutamine)) permeated selectively the DL membrane creating valuable permeate fractions (13 metabolites identified). This membrane generated the highest permeate flux (27.45–27.89 L/m 2 h), followed by the membranes NDX (18.47–20.16 L/m 2 h) and NFW (14.11–14.47 L/m 2 h), applying transmembrane pressures of 10, 30, and 25 bar, respectively. The DL one presented the highest recovery of total solids (22.21 %) in the permeate stream, followed by the membranes NDX (16.56 %) and NFW (16.28 %). Permeates containing attractive amino acids and phenolics were also generated by the membranes NFW (15 metabolites identified) and NDX (15 metabolites identified). The DL permeate contained the phenolics catechin, quercitrin, caffeic acid, caffeoyl-glucose, p-coumaric acid, and exclusively, the amino acids phenylalanine, lysine, and glutamine. Interesting permeate solutions proper for processing optimization in the food and pharmaceutical industries were generated.