title: Fast determination of bioactive phytic acid and pyrophosphate in walnuts using microwave accelerated extraction.
abstract: Bioactive compounds phytic acid (IP6) and pyrophosphate (PPi) are minor components of walnuts with the ability of being inhibitors of urolithiasis, among others. Since simultaneous analysis of IP6 and PPi have known drawbacks, a new method to determine their content in walnuts has been developed with emphasis on their extraction from walnuts by microwave-assisted extraction (MAE). Acid content of extracting solvent, extraction time and temperature were optimized. After extraction, compounds were purified by selective adsorption/desorption on an anion exchange solid phase extraction and analyzed by inductive coupled plasma/mass spectrometry. A mixture of H2SO4and HCl as solvent to extract both, IP6 and PPi, provided results slightly higher than those determined by conventional extraction with no statistical difference. The possible hydrolysis of phytic acid by MAE was analyzed. Compared with the conventional acid extraction method, significant improvement is achieved by the MAE method reducing extraction time from 3h to 10min.
authors.affiliation: Centre Grup de Tècniques de Separació en Química (GTS), Química Analítica, Departament de Química, Universitat Autònoma de Barcelona, 08193, Cerdanyola, Spain; Institute of Food Safety, Chinese Academy of Inspection and Quarantine, Bejing 100176, China. Electronic address: liutongyes@hotmail.com.
authors.forename: Tong
authors.initials: T
authors.lastname: Liu
authors.affiliation: Centre Grup de Tècniques de Separació en Química (GTS), Química Analítica, Departament de Química, Universitat Autònoma de Barcelona, 08193, Cerdanyola, Spain; State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: heliu2223@hotmail.com.
authors.forename: Liu
authors.initials: L
authors.lastname: He
authors.affiliation: Centre Grup de Tècniques de Separació en Química (GTS), Química Analítica, Departament de Química, Universitat Autònoma de Barcelona, 08193, Cerdanyola, Spain. Electronic address: Manuel.Valiente@uab.cat.
authors.forename: Manuel
authors.initials: M
authors.lastname: Valiente
authors.affiliation: Centre Grup de Tècniques de Separació en Química (GTS), Química Analítica, Departament de Química, Universitat Autònoma de Barcelona, 08193, Cerdanyola, Spain. Electronic address: Montserrat.Lopez.Mesas@uab.cat.
authors.forename: Montserrat
authors.initials: M
authors.lastname: López-Mesas
mesh_terms: D011756:Diphosphates / Q000032:analysis* / Q000302:isolation & purification; D031324:Juglans / Q000737:chemistry*; D008872:Microwaves; D010833:Phytic Acid / Q000032:analysis* / Q000302:isolation & purification; D052616:Solid Phase Extraction / Q000379:methods
chemical_list: D011756:Diphosphates; C107241:diphosphoric acid; D010833:Phytic Acid
keywords: Food analysis; Microwave-assisted extraction; Phytic acid; Pyrophosphate