Linking Soil, Water, and Honey Composition To Assess the

Apr 23, 2015 - The objective of this research was to investigate the development of a reliable fingerprint from elemental and isotopic signatures of A...
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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 is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

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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]

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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 (