title: Validated Method for the Characterization and Quantification of Extractable and Nonextractable Ellagitannins after Acid Hydrolysis in Pomegranate Fruits, Juices, and Extracts.
abstract: Pomegranates are one of the main highly valuable sources of ellagitannins. Despite the potential health benefits of these compounds, reliable data on their content in pomegranates and derived extracts and food products is lacking, as it is usually underestimated due to their complexity, diversity, and lack of commercially available standards. This study describes a new method for the analysis of the extractable and nonextractable ellagitannins based on the quantification of the acid hydrolysis products that include ellagic acid, gallic acid, sanguisorbic acid dilactone, valoneic acid dilactone, and gallagic acid dilactone in pomegranate samples. The study also shows the occurrence of ellagitannin C-glycosides in pomegranates. The method was optimized using a pomegranate peel extract. To quantify nonextractable ellagitannins, freeze-dried pomegranate fruit samples were directly hydrolyzed with 4 M HCl in water at 90 °C for 24 h followed by extraction of the pellet with dimethyl sulfoxide/methanol (50:50, v/v). The method was validated and reproducibility was assessed by means of an interlaboratory trial, showing high reproducibility across six laboratories with relative standard deviations below 15%. Their applicability was demonstrated in several pomegranate extracts, different parts of pomegranate fruit (husk, peels, and mesocarp), and commercial juices. A large variability has been found in the ellagitannin content (150-750 mg of hydrolysis products/g) and type (gallagic acid/ellagic acid ratios between 4 and 0.15) of the 11 pomegranate extracts studied.
authors.affiliation: †Research Group on Quality, Safety and Bioactivity of Plant Foods, CEBAS-CSIC, P.O. Box 164, 30100 Campus de Espinardo, Murcia, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: García-Villalba
authors.affiliation: †Research Group on Quality, Safety and Bioactivity of Plant Foods, CEBAS-CSIC, P.O. Box 164, 30100 Campus de Espinardo, Murcia, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Espín
authors.affiliation: §Fisheries and Aquaculture Research, Nofima - Norwegian Institute of Food, Osloveien 1, NO-1431 Ås, Norway.
authors.forename: Kjersti
authors.initials: K
authors.lastname: Aaby
authors.affiliation: #TÜBİTAK Marmara Research Center, Food Institute, Gebze-Kocaeli, Turkey.
authors.forename: Cesarettin
authors.initials: C
authors.lastname: Alasalvar
authors.affiliation: ⊥Food and Environmental Sciences, Division of Food Chemistry, P.O. Box 27, 00014 University of Helsinki, Finland.
authors.forename: Marina
authors.initials: M
authors.lastname: Heinonen
authors.affiliation: ΔVITO - Flemish Institute for Technological Research, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Griet
authors.initials: G
authors.lastname: Jacobs
authors.affiliation: ΔVITO - Flemish Institute for Technological Research, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Stefan
authors.initials: S
authors.lastname: Voorspoels
authors.affiliation: ⊥Food and Environmental Sciences, Division of Food Chemistry, P.O. Box 27, 00014 University of Helsinki, Finland.
authors.forename: Tuuli
authors.initials: T
authors.lastname: Koivumäki
authors.affiliation: ΠFood and Health Programme, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, United Kingdom.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kroon
authors.affiliation: #TÜBİTAK Marmara Research Center, Food Institute, Gebze-Kocaeli, Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Pelvan
authors.affiliation: ΠFood and Health Programme, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, United Kingdom.
authors.forename: Shikha
authors.initials: S
authors.lastname: Saha
authors.affiliation: †Research Group on Quality, Safety and Bioactivity of Plant Foods, CEBAS-CSIC, P.O. Box 164, 30100 Campus de Espinardo, Murcia, Spain.
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Tomás-Barberán
mesh_terms: D001628:Beverages / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004610:Ellagic Acid / Q000032:analysis; D005638:Fruit / Q000737:chemistry*; D006851:Hydrochloric Acid; D006868:Hydrolysis; D047348:Hydrolyzable Tannins / Q000032:analysis* / Q000302:isolation & purification; D029561:Lythraceae / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry*; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013056:Spectrophotometry, Ultraviolet; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D047348:Hydrolyzable Tannins; D010936:Plant Extracts; D004610:Ellagic Acid; D006851:Hydrochloric Acid
keywords: acid hydrolysis; ellagic acid; ellagitannin; interlaboratory reproducibility; pomegranate