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Linking soil, water and honey composition to assess the geographical origin of Argentinean honey by multielemental and isotopic analyses. María Verónica Baroni, Natalia S. Podio, Raúl Badini, Claudia M Inga, Héctor Adolfo Ostera, Mariana Cagnoni, Eduardo Gautier, Pilar Peral-García, Jurian Hoogewerff, and Daniel A. Wunderlin J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/jf5060112 • Publication Date (Web): 23 Apr 2015 Downloaded from http://pubs.acs.org on April 26, 2015
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Journal of Agricultural and Food Chemistry
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Linking soil, water and honey composition to assess the geographical origin of
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Argentinean honey by multielemental and isotopic analyses.
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María V. Baroni,† Natalia S. Podio,† Raúl G. Badini,‡ Marcela Inga,‡ Héctor A. Ostera,§
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Mariana Cagnoni,§ Eduardo A. Gautier,⊥ Pilar Peral García,∥ Jurian Hoogewerff,# and
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Daniel A. Wunderlin*,†
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†ICYTAC, Instituto de Ciencia y Tecnología de Alimentos Córdoba, CONICET and
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ISIDSA-Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad
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Universitaria, 5000 Córdoba, Argentina.
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‡Ministerio de Ciencia y Tecnología Provincia de Córdoba-CEPROCOR, Santa María de
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Punilla, Córdoba, Argentina.
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§Facultad de Ciencias Exactas y Naturales-INGEIS, Universidad de Buenos Aires-
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CONICET, Ciudad Universitaria, Buenos Aires, Argentina
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⊥Comisión Nacional de Energía Atómica, Gerencia Química, Centro Atómico
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Constituyentes, San Martín, Buenos Aires, Argentina
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∥Facultad de Ciencias Veterinarias-IGEVET, Universidad Nacional de La Plata-
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CONICET, Ciudad Universitaria, La Plata, Argentina
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#Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
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*Corresponding author:
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Dr. Daniel A. Wunderlin
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ICYTAC- CONICET- Universidad Nacional de Córdoba.
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Bv. Dr. Juan Filloy s/n, Ciudad Universitaria, 5000-Córdoba, Argentina.
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TE.: +54 351 433 3193/94 E-mail:
[email protected] ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
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ABSTRACT
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The objective of this research was to investigate if we could develop a reliable fingerprint
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from elemental and isotopic signatures of Argentinean honey to assess its geographical
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provenance. Honey, soil and water from three regions (Córdoba, Buenos Aires and Entre
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Ríos) were collected. The multi-elemental composition was determined by ICP-MS. δ13C
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was measured by isotopic ratio mass spectrometry, while
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using thermal ionization mass spectrometry. The data were analyzed by chemometrics
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looking for the association between the elements, stable isotopes and honey samples from
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three studied areas. Honey samples were differentiated by classification trees and
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discriminant analysis using a combination of 8 key variables (Rb, K/Rb, B, U,
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Na, La and Zn), presenting differences among the studied regions. The application of
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canonical correlation analysis and generalized procrustes analysis showed 91.5% consensus
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between soil, water and honey samples, in addition to clear differences between studied
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areas. To our knowledge, this is the first report demonstrating the correspondence between
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soil, water and honey samples using different statistical methods, showing that elemental
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and isotopic honey compositions are related to soil and water characteristics of the site of
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origin.
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Sr/86Sr ratio was determined
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Sr/86Sr,
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KEYWORDS
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honey, trace elements, isotopic composition, geographical origin, authenticity, traceability,
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fingerprint.
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Journal of Agricultural and Food Chemistry
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INTRODUCTION
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In these last years, authenticity and traceability of foodstuffs became a major requirement
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for consumers and producers worldwide. Food products have been linked to a specific
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geographical origin, however such links have disappeared over time mostly because of the
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globalization of the food industry 1 Food is becoming more regulated, with the increase in
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global trade and free markets. That’s why there is an increased need for developing new
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methods and techniques to discriminate different food origins, sources or farming systems.2
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Honey is a high value-added product which is of high interest for assessing its authenticity,
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(both geographical origin and floral sources). Additionally, the detection of not allowed
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substances, like syrups or sugars contributes to honey authenticity and safety.3,4 According
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to the European legislation (Council directive 2001/110), the country were honey was
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collected has to be declared. Honey with geographical and botanical origins declared are
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differently valued and, for that reason subjected to frauds, leading to doubtful labeling.3
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Honey chemical composition is generally associated to its botanical origin and, in less
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degree, to the geographical area where it was collected, since environment (soil and
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climate) determine the melliferous flora.5,6 For botanical origin classification, conventional
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methods (physical characteristics, chemical composition, pollen analysis and sensory
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parameters) are mainly used.3,7-10
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The multielemental content of food reflects the type of soil and environment conditions.11-13
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Honey contain between 0.04 to 0.2% (w/w) of trace elements. The soil composition of
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origin, determined by geochemical and geological features (i.e. regional geology and
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climatic changes), affects the composition and concentration of metals in honey.14,15 The
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botanical origin (nectar, pollen and floral type of honey plants) are also responsible for the
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metal content of honey.14,16 Furthermore, trace element contents in honey could also serve
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as indicator of environmental pollution.
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On the other hand, the analysis of stable isotopes has gained importance in the
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determination of the geographic origin of food. Stable-isotope measurements were first
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introduced within the European wine industry to ensure authenticity and to detect
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adulteration using carbon, oxygen and hydrogen mostly but also strontium.17 This
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measurements have been extended to many other foods (e.g., milk, meat, honey, juices,
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spirits and flavors).9,11-13,18,19 Small but significantly different ratios of stable isotopes can
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be correlated with the botanical-metabolic and/or geographical-geological origin of a
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product. Isotope ratios may add to the element fingerprint information on the plant type and
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the geographical-geological origin.20
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Even though there are many reports focusing on the elemental profile of honey,6,21-23 or on
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stable isotopes,9,19,24 there are few that combine both parameters.9 Even more, there are also
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few reports that consider the association with soil and water from places where honey is
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made.19 Furthermore, there has been little research on the determination of both the content
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of elements and stable isotopes in Argentinean honey.14,21,25 In this article, for the first time,
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we present the results of the determination of 33 elements and carbon and strontium
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isotopes in Argentinean honey from three different regions (Buenos Aires, Córdoba, and
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Entre Rios). Additionally, we were interested in demonstrating the link between honey, soil
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and water by applying different chemometric tools. To our knowledge, this is the first
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approach in Argentina on the combined use of Sr and C isotope ratios and multi-element
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analysis of soil, water and honey to assess its geographical origin.
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MATERIALS AND METHODS
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Journal of Agricultural and Food Chemistry
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Reagents and Materials. Ultrapure water (
