title: Ultrasound-Assisted Extraction, Centrifugation and Ultrafiltration: Multistage Process for Polyphenol Recovery from Purple Sweet Potatoes.
abstract: This work provides an evaluation of an ultrasound-assisted, combined extraction, centrifugation and ultrafiltration process for the optimal recovery of polyphenols. A purple sweet potato (PSP) extract has been obtained using ultrasonic circulating extraction equipment at a power of 840 W, a frequency of 59 kHz and using water as solvent. Extract ultrafiltration, using polyethersulfone (PES), was carried out for the recovery of polyphenol, protein and anthocyanin. Pre-treatment, via the centrifugation of purple sweet potato extract at 2500 rpm over 6 min, led to better polyphenol recovery, with satisfactory protein removal (reused for future purposes), than PSP extract filtration without centrifugation. Results showed that anthocyanin was efficiently recovered (99%) from permeate. The exponential model fit well with the experimental ultrafiltration data and led to the calculation of the membrane's fouling coefficient. The optimization of centrifugation conditions showed that, at a centrifugation speed of 4000 rpm (1195×g) and duration of 7.74 min, the optimized polyphenol recovery and fouling coefficient were 34.5% and 29.5 m-1, respectively. The removal of proteins in the centrifugation process means that most of the anthocyanin content (90%) remained after filtration. No significant differences in the intensities of the HPLC-DAD-ESI-MS² peaks were found in the samples taken before and after centrifugation for the main anthocyanins; peonidin-3-feruloylsophoroside-5-glucoside, peonidin-3-caffeoyl-p-hydroxybenzoylsophoroside-5-glucoside, and peonidin-3-caffeoyl-feruloyl sophoroside-5-glucoside. This proves that centrifugation is an efficient method for protein removal without anthocyanin loss. This study considers this process an ultrasound-assisted extraction-centrifugation-ultrafiltration for purple sweet potato valorization in "green" technology.
authors.affiliation: College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China. zhenzhouzhu@126.com.
authors.forename: Zhenzhou
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China. 13476183768@163.com.
authors.forename: Tian
authors.initials: T
authors.lastname: Jiang
authors.affiliation: College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China. jingren.he@whpu.edu.cn.fr.
authors.forename: Jingren
authors.initials: J
authors.lastname: He
authors.affiliation: Nutrition and Food Science Area, Preventive Medicine and Public Health, Food Science, Toxicology and Forensic Medicine Department, Faculty of Pharmacy, Universitat de València, Avda. Vicent Andrés Estellés, s/n, 46100 Burjassot, València, Spain. francisco.barba@uv.es.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Barba
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, University of Turin, Via P. Giuria 9, 10125 Turin, Italy. giancarlo.cravotto@unito.it.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cravotto
authors.affiliation: Centre de Recherche de Royallieu, Laboratoire Transformations Intégrées de la Matière Renouvelable (UTC/ESCOM, EA 4297 TIMR), Université de Technologie de Compiègne, CS 60319, 60203 Compiègne CEDEX, France. m.koubaa@escom.fr.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Koubaa
mesh_terms: D000872:Anthocyanins / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D027723:Ipomoea batatas / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D059808:Polyphenols / Q000302:isolation & purification*; D014465:Ultrasonics
chemical_list: D000872:Anthocyanins; D010936:Plant Extracts; D059808:Polyphenols
keywords: centrifugation; filtration; polyphenols; purple sweet potato; ultrasound