title: The use of δ(2)H and δ(18)O isotopic analyses combined with chemometrics as a traceability tool for the geographical origin of bell peppers.
abstract: Two approaches were investigated to discriminate between bell peppers of different geographic origins. Firstly, δ(18)O fruit water and corresponding source water were analyzed and correlated to the regional GNIP (Global Network of Isotopes in Precipitation) values. The water and GNIP data showed good correlation with the pepper data, with constant isotope fractionation of about -4. Secondly, compound-specific stable hydrogen isotope data was used for classification. Using n-alkane fingerprinting data, both linear discriminant analysis (LDA) and a likelihood-based classification, using the kernel-density smoothed data, were developed to discriminate between peppers from different origins. Both methods were evaluated using the δ(2)H values and n-alkanes relative composition as variables. Misclassification rates were calculated using a Monte-Carlo 5-fold cross-validation procedure. Comparable overall classification performance was achieved, however, the two methods showed sensitivity to different samples. The combined values of δ(2)H IRMS, and complimentary information regarding the relative abundance of four main alkanes in bell pepper fruit water, has proven effective for geographic origin discrimination. Evaluation of the rarity of observing particular ranges for these characteristics could be used to make quantitative assertions regarding geographic origin of bell peppers and, therefore, have a role in verifying compliance with labeling of geographical origin.
authors.affiliation: Mass Spectrometry of Biomacromolecules, Swammerdam Institute of Life Sciences, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands. Electronic address: e.derijke@uva.nl.
authors.forename: E
authors.initials: E
authors.lastname: de Rijke
authors.affiliation: Earth Surface Science, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands. Electronic address: J.C.Schoorl@uva.nl.
authors.forename: J C
authors.initials: JC
authors.lastname: Schoorl
authors.affiliation: Earth Surface Science, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands. Electronic address: c.cerli@uva.nl.
authors.forename: C
authors.initials: C
authors.lastname: Cerli
authors.affiliation: Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands. Electronic address: h.b.vonhof@vu.nl.
authors.forename: H B
authors.initials: HB
authors.lastname: Vonhof
authors.affiliation: Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands. Electronic address: s.j.a.verdegaal-warmerdam@vu.nl.
authors.forename: S J A
authors.initials: SJA
authors.lastname: Verdegaal
authors.affiliation: van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands. Electronic address: g.vivotruyols@uva.nl.
authors.forename: G
authors.initials: G
authors.lastname: Vivó-Truyols
authors.affiliation: Korteweg-de Vries Institute, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands; Netherlands Forensic Institute, P.O. Box 24044, 2490 AA The Hague, The Netherlands. Electronic address: m.lopatka@uva.nl.
authors.forename: M
authors.initials: M
authors.lastname: Lopatka
authors.affiliation: Naktuinbouw Laboratories, Sotaweg 25, P.O Box 40, 2370 AA Roelofarendsveen, The Netherlands. Electronic address: r.dekter@naktuinbouw.nl.
authors.forename: R
authors.initials: R
authors.lastname: Dekter
authors.affiliation: Naktuinbouw Laboratories, Sotaweg 25, P.O Box 40, 2370 AA Roelofarendsveen, The Netherlands. Electronic address: d.bakker@naktuinbouw.nl.
authors.forename: D
authors.initials: D
authors.lastname: Bakker
authors.affiliation: Korteweg-de Vries Institute, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands; Netherlands Forensic Institute, P.O. Box 24044, 2490 AA The Hague, The Netherlands. Electronic address: m.j.sjerps@uva.nl.
authors.forename: M J
authors.initials: MJ
authors.lastname: Sjerps
authors.affiliation: Naktuinbouw Laboratories, Sotaweg 25, P.O Box 40, 2370 AA Roelofarendsveen, The Netherlands. Electronic address: m.ebskamp@naktuinbouw.nl.
authors.forename: M
authors.initials: M
authors.lastname: Ebskamp
authors.affiliation: Mass Spectrometry of Biomacromolecules, Swammerdam Institute of Life Sciences, University of Amsterdam, Sciencepark 904, 1090 GE Amsterdam, The Netherlands. Electronic address: c.g.dekoster@uva.nl.
authors.forename: C G
authors.initials: CG
authors.lastname: de Koster
mesh_terms: D000473:Alkanes / Q000032:analysis; D002212:Capsicum / Q000737:chemistry*; D003903:Deuterium / Q000032:analysis; D016002:Discriminant Analysis; D005843:Geography; D007554:Isotopes / Q000032:analysis; D010103:Oxygen Isotopes / Q000032:analysis
chemical_list: D000473:Alkanes; D007554:Isotopes; D010103:Oxygen Isotopes; D003903:Deuterium
keywords: Bell peppers; Capsicum annuum; Food products authenticity; Gas chromatography; Geographic origin; Hentriacontane (PubChem CID: 12410); Heptacosane (PubChem CID: 11636); Isotope ratio mass spectrometry; Likelihood ratio; Linear discriminant analysis; Nonacosane (PubChem CID: 12409)