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Evaluation of polyphenolic compounds in membrane concentrated pistachio hull extract

Seifzadeh, Negin, Ali Sahari, Mohammad, Barzegar, Mohsen, Ahmadi Gavlighi, Hassan, Calani, Luca, Del Rio, Daniele, Galaverna, Gianni
Food chemistry 2019 v.277 pp. 398-406
2,2-diphenyl-1-picrylhydrazyl, antioxidant activity, artificial membranes, cellulose, fouling, gallic acid, hulls, mixing, pistachios, polyphenols, pyrogallol
Pistachio hull is a substantial source of natural polyphenols, but a substantial volume is being wasted annually. Aqueous pistachio green hull extract (PGHE) was subjected to two-stage membrane process in order to separate a polyphenol rich fraction. The membrane conditions of each stage were investigated. Total phenolic content and antioxidant activity were determined by Folin–Ciocalteu and DPPH· assay; also membrane fouling was monitored. The use of the 1 kDa cellulose membrane accompanied by 4 bar pressure and 250 rpm stirring speed was observed to be successful in the separation of a fraction with the highest amount of phenolic compound and antioxidant activity, in the retentate part. UHPLC/MSn characterization of PGHE polyphenols enabled us to identify 34 compounds, including the most abundant galloylshikimic acids, gallic acid, theogallin, galloyl-O-hexoside, quercetin-O-hexoside and pyrogallol.