Verifying the geographical origin of poultry: The application of stable isotope and trace element (SITE) analysis
Introduction
There is growing enthusiasm among consumers for high quality food with a clear regional identity. Motivations vary from (a) patriotism; (b) specific culinary, organoleptic qualities, or purported health benefits associated with regional products; (c) a decreased confidence in the quality and safety of foods produced outside their local region, country or the EU or (d) concern about animal welfare, ‘environmentally friendly’ production methods and ‘food miles’. Food scares such as chicken influenza and the malpractices of some international food producers (e.g. use of banned nitrofurans in chicken production) have added to public sensitivity regarding the validity of poultry origin labelling (Kelly, 2003). As a result of specific legislation (e.g. Food Information Regulations, EU 1169/2011) and general public concerns, there is a need for reliable analytical methods that can verify origin labels describing where poultry has been reared prior to slaughter. In addition, analytical identification of meat origin from outside the EU is a valuable tool for European enforcement authorities.
A common theme of food authentication studies is the requirement for a database of genuine samples to which a questionable test sample can be compared to establish its authenticity. Geographical origin determination is no exception, but the need to source agricultural products from a wide range of countries is time consuming and costly. Furthermore, in order to constrain an authenticity parameter such as geographical origin there may be a requirement for a large number of independent variables to be measured and statistically ‘screened’ in order to identify key tracers that differentiate the regions or countries of interest. There have been a number of literature reviews dedicated entirely (or at least in part) to the application of multi-element and multi-isotope analysis to the determination of food provenance. These include Horn et al., 1997, Anklam, 1998, Rossmann, 2001, Kelly, 2003, Kelly et al., 2005 and Hölzl, Horn, Rossmann, and Rummel (2004). In addition the multivariate statistical techniques used, in combination with a wide range of analytical methods including multi-element and isotopic analysis, to classify food products according to their geographical and varietal origin has been critically reviewed by Tzouros and Arvanitoyannis (2001). Measuring elemental concentrations and isotopic variation in premium regional products is arguably the best analytical strategy for accurately verifying geographical origin.
There have only been two publications relating specifically to the determination of the geographical origin of poultry on relatively small sample sets. Franke, Haldimann et al., (2007) measured the concentrations of a total of 72 different elements in 25 poultry breast fillets originating from Switzerland (n = 7), France (n = 2), Germany (n = 3), Hungary (n = 6), Brazil (n = 4), and Thailand (n = 3), by inductively coupled plasma high resolution mass spectrometry (ICP-HRMS). Analysis of variance was used to identify elements that were significantly different between the countries of origin examined. Mean concentrations of four elements; arsenic, sodium, rubidium and thallium were found to be significantly different. However, the discrimination power among countries depends on the numbers of observations, which were low.
Franke, Koslitz et al., (2007) also report strontium isotope data for 22 poultry samples and δ18O ‰ data for water extracted from 78 poultry samples. The average values of 87Sr/86Sr were numerically lowest for poultry meat samples from Germany and highest for samples from Hungary. However, the pairwise comparison among means (with conservative Bonferoni adjustment) did not specify any individual differentiation. Analysis of variance of the poultry breast meat tissue water δ18O ‰ showed significant differences between Brazil, Germany, Hungary and Switzerland. However, the use of tissue water for δ18O ‰ analysis has been shown to be significantly affected by storage conditions. Increasing open storage times, including post-mortem hanging or maturing result in decreasing meat juice yield, increasing weight loss and increasing 18O/16O-ratio values in extracts with higher rates of change associated with higher ambient storage temperatures, probably due to evaporation (Thiem, Lüpke, & Seifert, 2004). The technique therefore does not readily lend itself to the analysis of ‘off the shelf’ retail samples unless the chilled storage history is well known.
The aims of this project were to develop reliable analytical methods that could establish the geographical origin of chicken based on its trace element ‘fingerprint’ and the natural abundance stable isotope ratios of the biological-elements hydrogen, carbon, nitrogen and oxygen and the heavy element strontium commonly found in all animal tissues. Here we present the findings from 384 poultry samples originating from Europe, China, Brazil, Chile, Thailand and Argentina.
Section snippets
Materials and methods
Three hundred and eighty four authentic poultry samples were obtained for this study. The vast majority of these samples (over 95%) were chicken samples, the remainder were turkey. The samples originated from seventeen different countries: Argentina (10 samples equivalent to 3% of total), Brazil (106, 27%), Chile (46, 12%), China (83, 22%), Thailand (37, 10%) and Europe (102, 26%). The 102 European samples originated from Austria (7), Czech Republic and Slovakia (1), Denmark (21), France (25),
Evaluation of poultry defatted dry mass (DDM) δ13C ‰ and δ15N ‰ isotopic measurements
The mean δ13C ‰ and δ15N ‰ values obtained from authentic European, Argentinean, Brazilian, Chilean, Thai and Chinese poultry DDM are summarised in Table 1. The Table also shows the sample standard deviation (σn-1) and the number of authentic samples measured (n). The difference in δ13C ‰ values between the South American (∼17.5‰) and European poultry (∼22.5‰) is relatively smaller than that observed for beef DDM (difference ∼ 10‰) (Heaton et al., 2008). This is probably due to a number of
Conclusions
This project has demonstrated that the stable isotopes of hydrogen in chicken meat change in accordance with hydrogen isotope ratios in surface waters around the globe. The findings support the theory that the global isotopic variation of hydrogen in drinking water is transferred into animal tissue and can be used to help establish an animal's geographic origin.
Furthermore, in some instances one variable was shown to be sufficient to discriminate geographical origins. For example, carbon stable
Acknowledgements
This research was financed by the UK Food Standards Agency as part of their Food Authenticity and Labelling Programme. The views expressed here are those of the authors and do not necessarily reflect the views of the UK Food Standards Agency.
The authors would also like to thank the following for their help in providing authentic poultry samples: The Port Health Authorities (UK), Bernard Matthews Ltd (Norwich, UK).
IQSTAP – Institute of Quality Standards and Testing Technology for Agricultural
References (32)
A review of the analytical methods to determine the geographical and botanical origin of honey
Food Chemistry
(1998)- et al.
Verifying the geographical origin of beef: the application of multi-element isotope and trace element analysis
Food Chemistry
(2008) Using stable isotope ratio mass spectrometry (IRMS) in food authentication and traceability
- et al.
Tracing the geographical origin of food: the application of multi-element and multi-isotope analysis
Trends in Food Science and Technology
(2005) - et al.
From birds to butterflies: animal movement patterns and stable isotopes
Trends in Ecology & Evolution
(2004) - et al.
Carbon and nitrogen stable isotope composition of cattle hair: ecological fingerprints of production systems?
Agriculture Ecosystems & Environment
(2005) - et al.
Nitrogen isotope relationships between crops and fertilizer: Implications for using nitrogen isotope analysis as an indicator of agricultural regime
Journal of Agricultural and Food Chemistry
(2005) - et al.
Global application of stable hydrogen and oxygen isotopes to wildlife forensics
Oecologia
(2005) - et al.
Multi-element (H, C,N,S) stable isotope characteristics of lamb meat from different European regions
Analytical and Bioanalytical Chemistry
(2005) - et al.
Environmental isotopes in hydrogeology
(1997)
Isotopic variations in meteoric waters
Science
Stable isotopes in precipitation
Tellus
Regulation (EU) No 1169/2011 of the European Parliament and of the council of 25 October 2011
Off. J. Eur. Union
Indications for the applicability of element signature analysis for the determination of the geographic origin of dried beef and poultry meat
European Food Research and Technology
Tracing the geographic origin of poultry meat and dried beef with oxygen and strontium isotope ratios
European Food Research and Technology
Tracing origins and migration of wildlife using stable isotopes: a review
Oecologia
Cited by (38)
A comprehensive overview of emerging techniques and chemometrics for authenticity and traceability of animal-derived food
2023, Food ChemistryCitation Excerpt :Fortunately, measures and techniques to identify the geographical origin traceability and authenticity of animal-derived food have also being increased (Valdés, Beltrán, Mellinas, Jiménez, & Garrigós, 2018). At present, stable isotope analysis and elemental analysis are extensive used to identify the geographic origin and adulteration of animal-derived food (Erasmus, Muller, van der Rijst, & Hoffman, 2016; Rees, Kelly, Cairns, Ueckermann, Hoelzl, Rossmann et al., 2016). The δ13C of diverse animal tissues (muscle or lipid) is highly impacted by the composition of the animal's diet.
Stable isotopes verify geographical origin of Tibetan chicken
2021, Food ChemistryCitation Excerpt :δ13C value of poultry from Japan did not differ among muscle tissue samples from different body parts, but the values clearly varied among samples from China, Japan and the USA (Sakamoto et al., 2002). Rees et al. determined the δ13C, δ15N, δ2H and δ18O values in chicken samples from five countries (China, Brazil, Chile, Thailand and Argentina), δ13C of chicken leads to useful discrimination between a large proportion of European chicken and chicken reared in locations such as South America, Thailand and China (Rees et al., 2016). Stable isotope technique plays an important role in distinguishing the geographical origin of chicken, which is reflected not only in the traceability of chicken from different countries, but also in the traceability of chicken sample from different provinces in the same country.
Geographic origin discrimination of pork from different Chinese regions using mineral elements analysis assisted by machine learning techniques
2021, Food ChemistryCitation Excerpt :Regarding the authentication of meat, the reported works are focused on the analysis of volatile compounds (Arredondo et al., 2014) or spectrum data (Parastar et al., 2020). The main data analysis methods used in the study of geographic origin by trace element content are traditional multivariate statistical analyses, such as PCA and LDA (Franke et al., 2008; Sun et al., 2011) or PCA and canonical discriminant analysis (CDA) (Rees et al., 2016). The traditional data statistical analysis method is based on a data model that limits the data to the assumption model.
Trace elements and machine learning for Brazilian beef traceability
2020, Food ChemistrySpatial variations in oxygen and hydrogen isotopes in waters and human hair across South Korea
2020, Science of the Total Environment