Continuous flow tangential nanofiltration process to optimize the purification and recovery of bioactive compounds from noni tea (Morinda citrifolia L.): a sustainable approach of flow properties, biodigestibility and biochemical profile

Morinda citrifolia, known as noni, is a fruit whose processing results in the disposal of a large amount of leaves with high phytotherapeutic value. This study presents an unprecedented approach to the reuse of noni leaves, proposing the use of nanofiltration membranes aiming at the recovery, purification and concentration of bioactive compounds. The main process parameters were analyzed under different separation conditions, getting an optimized process capable of generating a concentrate rich in antioxidants and bioactive compounds. Nanofiltration was carried out on a polyvinylidene fluoride spiral polymeric membrane with a molar mass cut-off ranging between 150 and 300 Da. The best operating condition was selected at 35 degrees C and nominal pressure of 5 bar, via permeate flow analysis, resistance, and retention in the membrane. The retained product was 8 and 15 times more concentrated than the respective total solids and phenolic contents found in the initial feed. The antioxidant activity resulted in a retention efficiency greater than 99%. Catechin, ferulic acid and myricetin were the bioactive retained in greater quantity after high-performance liquid chromatography assays. Finally, in vitro tests of gastrointestinal biodigestion resulted in a low loss of biological activity of the retained product, qualifying it as a functional food, nutraceutical, and highly promising for application as a natural antioxidant.