Concentration of phenolic compounds from an orange peel waste extract using a combination of ultrafiltration and forward osmosis

Orange juice production industry generates tons of solid waste annually, losing the opportunity of recovering high added value bioactive compounds, such as polyphenols. Solid-liquid extraction was previously studied for extracting the phenolic compounds from the solid waste to a liquid stream. In this work, an integrated membrane process has been investigated for the purification and concentration of phenolic compounds from the orange extract. First, a pretreatment was performed using ultrafiltration membranes to purify the extract and to minimize membrane fouling in the following concentration step, due to the large pectin content of the orange extract. After studying several ultrafiltration membranes, the best results were obtained using the UP010 membrane (10 kDa), separating a significant amount of pectins (50 %). Flavonoids experienced low rejection values, being preferentially recovered in the permeate. The ultrafiltration permeate was then concentrated with forward osmosis using 58 g·L -1 NaCl as draw solution. Polyphenols were concentrated 2.03 times. Moreover, an insignificant amount of phenolic compounds, sugars and pectins passed through the membrane to the draw solution. Globally, the polyphenols were concentrated achieving a concentration factor of 1.47 in the whole integrated membrane process.