geographic origin (11)

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Methods to determine the geographic origin of EVOO are a useful tool to prevent fraud for this high value oil. Portuguese researchers have applied SIRA of carbon, oxygen and hydrogen (δ13C, δ2H and δ18O) with chemometrics to verify whether the geographical origin of VOOs obtained from three Mediterranean countries can be determined. One hundred and thirty eight authentic VOO samples were collected from Portugal, France and Turkey from two different harvest years (2016 and 2017). The samples were analysed for the isotopic ratios using an elemental analyser coupled to an isotope ratio mass spectrometer (EA-IRMS). Using meteorological and geographical parameters, a meteoric water line for olive oil from Portugal, France and Turkey, in two harvest years, were created to assess the impact of climate change on their δ2H and δ18O values. After principal component analysis, the VOOs from Portugal and France were well separated, Turkey slightly less so, but also the 2016 and 2017 harvest years of each country were also discriminated.  

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8169733900?profile=RESIZE_400xItalian researchers have developed a method based on FT-NIR (Fourier transform - near infrared) spectroscopy combined with chemometrics to authenticate pasta made exclusively with durum wheat. In addition, the objective of this study was to verify that the pasta was made with 100% Italian durum wheat. The 361 samples used were pasta marketed in Italy and made with durum wheat cultivated in Italy (n = 176 samples), and on pasta made with mixtures of wheat cultivated in Italy and/or abroad (n = 185 samples). The samples were analysed by FT-NIR spectroscopy coupled with supervised classification models. Good performance results of the validation set (sensitivity of 95%, specificity and accuracy of 94%) were obtained using principal component-linear discriminant analysis (PC-LDA), which clearly demonstrated the high prediction capability of this method. 

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This study compared the capabilities of three spectroscopic techniques as fast screening platforms for honey authentication purposes. Multifloral honeys were collected in the three main honey-producing regions of Argentina over four harvesting seasons to give a total of 502 samples. Spectra were run on each of the samples with FT-MIR ( Fourier transform mid-infrared), NIR (near infrared) and FT-Raman  (Fourier transform Raman)  spectroscopy. The spectroscopic platforms were compared on the basis of the classification performance achieved under a supervised chemometric approach. Very good classification scores to distinguish the three Argentian regions were achieved by all the spectroscopies, and a nearly perfect classification was provided by FT-MIR. The results obtained in the present work suggested that FT-MIR had the best potential for fingerprinting-based honey authentication, and demonstrated that sufficient accuracy levels to be commercially useful can be reached.

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4340822886?profile=RESIZE_710xDetermining the geographic origin of coffee beans is more challenging with roasted coffee beans, and is useful if it can be performed on the product available to the consumer. US researchers analysed the concentrations of 44 trace elements in 53 samples of roasted Arabica coffee beans (Coffea arabica) from 21 different countries. Although trace elements are not volatilised at roasting temperatures, the absolute elemental concentrations of coffee beans vary through different degrees of roasting (from green through dark roasts). The study analysed trace element ratios to evaluate concentration-related differences among beans from different origins. By comparing the distributions of 1892 element ratios for each of the  countries, the study demonstrated that many of the world’s coffee-producing regions can be distinguished from other regions of the world on the basis of element ratios.

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3925480647?profile=RESIZE_710xThe assessment of durum wheat geographical origin is an important and emerging challenge, due to the added value that a claim of origin could provide to the raw material itself, and subsequently to the final products (i.e. pasta). As an alternative to the use of stable isotopes and trace elements to determine geographic origin, Italian researchers used non-targeted high resolution mass spectrometry (LC-HRMS) to select chemical markers related to the geographical origin of durum wheat. Durum wheat samples from the 2016 wheat harvest were used to set up the model and to select the markers, while samples from the 2018 harvest were used for model and metabolomic markers validation. Different geographies across different continents were used in the sample set, so that it is now possible to discriminate between Italian, European and Non-European durum wheat samples.

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This research is by the same French team, who reported using elemental strontium and strontium isotopes as markers for geographic origin and authenticity of Bordeaux wines, which was reported as a 27 April 2019 News item. In this research, lead (Pb) concentrations and Pb isotope ratios of 43 authentic Bordeaux wines from prestigious châteaux and 14 suspicious Bordeaux origin were determined to evaluate their potential as markers for authenticity and geographical origin. Total Pb concentrations in Bordeaux wines have drastically decreased over the past 50 years corresponding to changes in environmental lead concentrations with a clear shift of isotopic signatures towards geological values. The Pb isotopic ratios determined in both sets of samples clearly demonstrated that the suspicious Bordeaux wines displayed Pb isotopic signatures statistically distinctive from those obtained for authentic Bordeaux wines. Three isotopic ratio signatures using the geological and environmental Pb isotopes data that characterise European and Asian sources were used to give a non-ambiguous discrimination between authentic Pauillac AOC and the counterfeit wines.   

3436675196?profile=RESIZE_710x Read the abstract here

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Bordeaux wines are highly valued and sought after, and hence vulnerable to counterfeiting. French reseachers have used strontium concentration and strontium isotope ratios as markers for Bordeaux wine geographic origin and authenticity. Forty three authentic Bordeaux wines were collected from the world’s most prestigious Bordeaux châteaux. The Sr elemental composition and 87Sr/86Sr ratio were determined on these authentic wines. The results demonstrated relatively small variabilities for 87Sr/86Sr ratio and Sr concentrations in the authentic Bordeaux wines, which can be used with reasonable certainty to identify regional Bordeaux wineries and distinguish them from counterfeit wines.

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The Olive Oil Marketing Regulation requires that olive oils of mixed origin have to be designated as either EU and/or non-EU origin. In this study 2H/1H, 13C/12C and 18O/16O ratios were analysed in bulk olive oils using  isotope ratio mass spectrometry (IRMS) as well as 13C/12C and 2H/1H in the four main fatty acids (linoleic, oleic, palmitic and stearic acids) using IRMS coupled with GC (gas chromatography). The isotopic composition of olive oils was successfully used to distinguish samples originating in the two areas. When bulk data were combined with fatty acid isotopic data the differentiation power of the method was improved. The improvement is due to the specific isotopic fingerprint of the individual countries making up the EU and non-EU samples. 

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Chinese researchers have developed an integrated approach combining HPLC/DAD, GC/MS, near infrared (NIR) spectroscopy, and chemometrics  to geographically discriminate saffron samples from Iran and China. Using a dataset based on 98 samples of saffron, the saffron compounds picrocrocin and two types of crocins were found to be the discriminating markers, and the Chinese samples had higher contents of safranal and picrocrocin but lower cis-crocin 3Gg, kaempferol-3-O-sophoroside and isophorone. 

 Furthermore, an NIR method was successfully established to rapidly distinguish the Chinese and Iranian samples. The relationship between an ISO standard and the contents of the chemical indices was also studied. The results indicated that the ISO standard should be revised, especially for analysing safranal.

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Marketing of cocoa and chocolate products made from single origin cocoa is becoming more popular. However, a reliable analytical method able to verify the geographical origin of cocoa is lacking. The potential of HR MAS 1H NMR (Magic-angle spinning NMR in solid state) on cocoa powder combined with chemometrics for metabolic profiling was assessed for the geographical origins of 60 fermented and dried cocoa beans of 23 different cocoa producing countries from the three major crop-growing areas (Africa, Central/South America, Asia/Oceania) was evaluated. The same samples were also subjected to extraction and analysis with liquid solution 1H NMR. The same metabolites were determined by both methods apart from the additional determination of of cocoa lipids by HR MAS 1H NMR, which were lost in the extraction for liquid 1H NMR. HR MAS 1H NMR  gave better discrimination in the verification of geographical origin.

Read the abstract at: NMR determination of cocoa origin

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A study has been completed to look at the ratio of stable isotopes of  δ18O, (D/H)I, (D/H)II, δ13C, δ15N and 87Sr/86Sr moving from the soil, through the cultivation of grapes and their preparation at different stages into wine.  The isotopic ratio of 87Sr/86Sr does not vary significantly from grape to wine, and δ15N has been proposed as further isotopic marker for the geographical characterisation of grape products.

The paper in Food Chemistry by Caterina Durante et al is in press, but the abstract can be read at http://www.sciencedirect.com/science/article/pii/S0308814616306318

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