title: Ultrasound-assisted extraction of amino acids from grapes.
abstract: Recent cultivar techniques on vineyards can have a marked influence on the final nitrogen content of grapes, specifically individual amino acid contents. Furthermore, individual amino acid contents in grapes are related to the final aromatic composition of wines. A new ultrasound-assisted method for the extraction of amino acids from grapes has been developed. Several extraction variables, including solvent (water/ethanol mixtures), solvent pH (2-7), temperature (10-70°C), ultrasonic power (20-70%) and ultrasonic frequency (0.2-1.0s(-)(1)), were optimized to guarantee full recovery of the amino acids from grapes. An experimental design was employed to optimize the extraction parameters. The surface response methodology was used to evaluate the effects of the extraction variables. The analytical properties of the new method were established, including limit of detection (average value 1.4mmolkg(-)(1)), limit of quantification (average value 2.6mmolkg(-)(1)), repeatability (average RSD=12.9%) and reproducibility (average RSD=15.7%). Finally, the new method was applied to three cultivars of white grape throughout the ripening period.
authors.affiliation: Andalusian Center for Wine Research, Agrifood Campus of International Excellence (ceiA3), University of Cádiz, Campus de Puerto Real, 11510 Puerto Real, Cádiz, Spain.
authors.forename: Ceferino
authors.initials: C
authors.lastname: Carrera
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, Agrifood Campus of International Excellence (ceiA3), University of Cádiz, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Ruiz-Rodríguez
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, Agrifood Campus of International Excellence (ceiA3), University of Cádiz, Spain. Electronic address: miguel.palma@uca.es.
authors.forename: Miguel
authors.initials: M
authors.lastname: Palma
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, Agrifood Campus of International Excellence (ceiA3), University of Cádiz, Spain.
authors.forename: Carmelo G
authors.initials: CG
authors.lastname: Barroso
mesh_terms: D000596:Amino Acids / Q000302:isolation & purification*; D005591:Chemical Fractionation / Q000379:methods*; D007700:Kinetics; D012997:Solvents / Q000737:chemistry; D013997:Time Factors; D014465:Ultrasonics; D027843:Vitis / Q000737:chemistry* / Q000254:growth & development; D014920:Wine
chemical_list: D000596:Amino Acids; D012997:Solvents
keywords: Amino acids; Grapes; Ultrasound-assisted extraction