Removal of Polyphenols and Recovery of Proteins from Alfalfa White Protein Concentrate by Ultrafiltration and Adsorbent Resin Separations

The peptides remaining after phenol removal from a co-product of the alfalfa industry have various applications: in the food industry (as an additive), in therapeutic nutrition (high-value protein, peptides with opioid or immunostimulant activities, etc.), and in cosmetics. Hydrolysis of alfalfa white protein concentrate (AWPC) by an industrial enzyme (Delvolase) improved its solubility and nutritional properties. But, colored peptidic hydrolysate was observed. This color change was due to phenolic oxidation at alkaline pH. A combined ultrafiltration process and sorption technique was investigated. A ZrO 2 Carbosep membrane (nominal molecular weight cutoff of 10,000 Da) allowed a 51% color reduction and a 96% peptide transmission. The colored peptide fraction in the permeate had a known and reproducible molecular-weight distribution. Permeate polyphenol removal was performed by a sorption technique. A polystyrene resin, Amberlite IRA900Cl, packed in a column, allowed a 92-95% phenol extraction while preserving peptide fractions.