Variation of strontium stable isotope ratios and origins of strontium in Japanese vegetables and comparison with Chinese vegetables

Measurement of 90Sr and 87Sr/86Sr isotope ratio in Japanese cow milk sample using thermal ionization mass spectrometry

The pure beta emitter 90Sr (T1/2 = 28.8y) is a typical contaminant released by nuclear accidents and nuclear explosions. In the event of a nuclear disaster, it is crucial to identify radioactive pollutants quickly, to expedite the public's awareness of radiation exposure. In this work, a rapid 90Sr analysis protocol using thermal ionization mass spectrometry (TIMS) was developed for milk samples. With the improved sample preparation, Sr separation, and a newly developed TIMS method, 18 milk samples can be analyzed in less than 30 h and only 1 mL of cow milk is required for the complete analysis. The minimum detectable activity concentration of 90Sr is affected by the stable Sr concentration therefore, it is around 500 mBq·kg-1 (∼100ag·g-1). Additionally, 87Sr/86Sr isotope ratios (0.71518(9)-0.74132(4)) were determined for the first time in Japanese cow milk samples.

La Sassa cave: Isotopic evidence for Copper Age and Bronze Age population dynamics in Central Italy

This study focuses on the changes in diet and mobility of people buried in the La Sassa cave (Latium, Central Italy) during the Copper and Bronze Ages to contribute to the understanding of the complex contemporary population dynamics in Central Italy. To that purpose, carbon and nitrogen stable isotope analyses, strontium isotope analyses, and FT-IR evaluations were performed on human and faunal remains from this cave. The stable isotope analyses evidence a slight shift in diet between Copper and Bronze Age individuals, which becomes prominent in an individual, dating from a late phase, when the cave was mainly used as a cultic shelter. This diachronic study documents an increased dietary variability due to the introduction of novel resources in these protohistoric societies, possibly related to the southward spread of northern human groups into Central Italy. This contact between different cultures is also testified by the pottery typology found in the cave. The latter shows an increase in cultural intermingling starting during the beginning of the middle Bronze Age. The local mobility during this phase likely involved multiple communities scattered throughout an area of a few kilometers around the cave, which used the latter as a burial site both in the Copper and Bronze ages.

Authenticating teas using multielement signatures, strontium isotope ratios, and volatile compound profiling

High value food products are subject to adulterations and frauds. This study aimed to combine, in our knowledge for the first time, inorganic chemical tracers (multi-elements and Sr isotopy) with volatile organic compound (VOCs) to discriminate the geographic origin, the varieties and transformation processes to authenticate 26 tea samples. By measuring Sr isotope ratio using the multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), 6 out of 11 regions were successfully discriminated. The combination with the ICP-MS inorganic pattern allowed to discriminate 4 more regions with a significance level of 0.05. VOCs fingerprints, obtained with selected ion flow tube mass spectrometer (SIFT-MS), were not correlated with origin but with the cultivar and transformation processes. Green, oolong, and dark teas were clearly differentiated, with hexanal and hexanol contributing to the discrimination of oxidation levels. With this multi-instrumental approach, it is possible to certify the geographical origin and the tea conformity.

Multi-chemical analysis combined with chemometrics to characterize PDO and PGI Italian apples

BACKGROUND

The use of PDO (protected designation of origin) and PGI (protected geographical indication) labels allows to protect and promote agricultural products characterized by unique features related to the place of origin and traditional know-how. However, the presence of non-authentic products in the market represents a fraud that can be tackled applying analytical techniques combined with chemometric analysis. In this study, we applied multi-element and multi-isotope analysis to characterize PDO and PGI apples cultivated in northern Italy, comparing them with Italian apples without labels of geographical indications.

RESULTS

The multi-element and multi-isotope approach allowed to characterize the apples cultivated in northern Italy. Despite a significant effect of the sampling sites on the apple composition, the comparison of the multi-chemical fingerprint of the apples significantly varied among cultivation areas. Results of this characterization were used to classify samples according to their cultivation area applying a linear discriminant analysis (LDA). Outputs of the LDA showed that correct sample classification can be successfully achieved (balanced accuracy > 96%). Moreover, using a selection of variables, it was possible to correctly classify samples also at regional level.

CONCLUSION

The presented evidences indicate that the multi-element and multi-isotope fingerprint can be successfully applied to traceability studies. The combination of this characterization with chemometric tools allows the classification of Italian apples based on their origin both on a national and regional scale. This approach represents an interesting tool to enhance and protect PDO and PGI Italian products. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Isotope chemometrics determines farming methods and geographical origin of vegetables from Yangtze River Delta Region, China

Shanghai city has encountered possible food fraud regarding the geographical mislabeling of vegetables for economic gain. A combination of δ¹³C, δ¹⁵N, δ²H and δ¹⁸O values and partial least squares discrimination analysis and support vector machine (SVM) methods were used for the first time to assess farming methods and determine the origin of vegetables from Shanghai city, Anhui and Zhejiang provinces. The results showed that 65.8% of Shanghai vegetables, 38.2% of Anhui vegetables and 23.6% of Zhejiang vegetables appeared to be grown using green or organic farming methods. The optimal discriminant model was obtained using SVM with a predictive accuracy of 100% for Shanghai vegetables. Zhejiang vegetables had a predictive accuracy of 91.7%, while it was difficult to distinguish Anhui vegetables from Shanghai or Zhejiang vegetables. Therefore, this study provided a useful method to identify vegetable farming methods and discriminate vegetables from Shanghai and Zhejiang.

Sr isotope composition of Golden Delicious apples in Northern Italy reflects the soil 87 Sr/86 Sr ratio of the cultivation area

BACKGROUND

Apples have a leading role in the Italian fruit sector, and high-quality apples, including the Golden Delicious variety, are cultivated mainly in the Northern mountain districts. In the present study, Golden Delicious apples from PDO (Protected Designation of Origin) and PGI (Protected Geographical Indication) cultivation districts were characterized according to their Sr isotope composition and compared with apples from other Northern Italian districts.

RESULTS

Apples collected in two consecutive years (2017 and 2018) confirmed the low annual variability of the ⁸⁷ Sr/⁸⁶ Sr ratio. The isotope ratio of apples was highly correlated with that of the soil extracts of the respective orchards. Statistical differences were highlighted between cultivation districts. However, because similar geological features characterized some areas, their ratios overlapped and a complete separation of the districts was not possible.

CONCLUSION

The ⁸⁷ Sr/⁸⁶ Sr ratio is an excellent marker for studies of food traceability because it retains the information about the place of origin. However, its strength is limited when comparing products from cultivation areas sharing similar geological features. In the perspective of geographical traceability, a multichemical characterization can overcome the limits of single-parameter approach. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Can We Discover Truffle's True Identity?

This study used elemental and stable isotope composition to characterize Slovenian truffles and used multi-variate statistical analysis to classify truffles according to species and geographical origin. Despite the fact that the Slovenian truffles shared some similar characteristics with the samples originating from other countries, differences in the element concentrations suggest that respective truffle species may respond selectively to nutrients from a certain soil type under environmental and soil conditions. Cross-validation resulted in a 77% correct classification rate for determining the geographical origin and a 74% correct classification rate to discriminate between species. The critical parameters for geographical origin discriminations were Sr, Ba, V, Pb, Ni, Cr, Ba/Ca and Sr/Ca ratios, while from stable isotopes δ18O and δ13C values are the most important. The key variables that distinguish T.magnatum from other species are the levels of V and Zn and δ15N values. Tuber aestivum can be separated based on the levels of Ni, Cr, Mn, Mg, As, and Cu. This preliminary study indicates the possibility to differentiate truffles according to their variety and geographical origin and suggests widening the scope to include stable strontium isotopes.

Geographic variation of Sr and S isotope ratios in bottled waters in Japan and sources of Sr and S

The geographic distribution of the stable isotope ratio of Sr (⁸⁷Sr/⁸⁶Sr) is useful for identifying the provenance of drinking water, organisms, and agricultural products. To explore how environmental factors influence this ratio, we determined the ⁸⁷Sr/⁸⁶Sr, sulfur isotope ratio (δ³⁴S), and elemental composition of 208 commercially available bottled waters in Japan, and compared them with the ⁸⁷Sr/⁸⁶Sr values of groundwater, rainwater, rocks, and vegetables from similar localities. We classified the bottled waters into seven categories based on the geology of their source aquifers. The ⁸⁷Sr/⁸⁶Sr and concentrations of several elements (Ca, K, Si, Rb, and Ba) of the bottled waters differed with the aquifer rock type and were well correlated with the ⁸⁷Sr/⁸⁶Sr of reported spring waters, indicating that bottled water, like other groundwater, reflects the lithology and chemistry of its aquifer. The ⁸⁷Sr/⁸⁶Sr of bottled water, taken as a proxy for groundwater, showed regional variations consistent with those of rocks and vegetables, demonstrating that an ⁸⁷Sr/⁸⁶Sr map of water and agricultural products has value for determining the production areas of these substances. However, the value and range of ⁸⁷Sr/⁸⁶Sr differed among these three materials, and the degree of the difference between groundwater and rock depended on the rock type. An analysis of geochemical data from rocks and rainwater suggests that groundwater contains Sr and additional S derived from atmospheric sources such as rainwater and sea salt aerosols. The atmospheric contribution of Sr to groundwater is greatest in areas of siliceous sedimentary rocks with low Sr concentrations and high resistance to weathering. A weak correlation of δ³⁴S of bottled waters with ⁸⁷Sr/⁸⁶Sr indicates the usefulness of maps of combined Sr and S isotope ratios for groundwater provenance. This study shows that for accurate provenance determinations of groundwater, organisms, and agricultural products, it is essential to better quantify the contributions of Sr and S from the atmosphere as well as from rocks and human activities.

Intra- and Intertree Variability of the 87Sr/86Sr Ratio in Apple Orchards and Its Correlation with the Soil 87Sr/86Sr Ratio

The ⁸⁷Sr/⁸⁶Sr ratio of horticultural products mostly derives from that of the bioavailable Sr fraction of the soil where they grow and, therefore, varies according to the local geolithological features. This study investigated the intra- and intertree variability of the ⁸⁷Sr/⁸⁶Sr ratio in two apple orchards in South Tyrol and its relation with the soil ⁸⁷Sr/⁸⁶Sr ratio. In both orchards, a moderate homogeneity of the ⁸⁷Sr/⁸⁶Sr ratio was observed among subsamples of the same tree part (shoot axes, leaves, apple peels, and pulps). Moreover, the ⁸⁷Sr/⁸⁶Sr ratio homogeneity among tree parts was high intratree and low intertree. The variability of the ⁸⁷Sr/⁸⁶Sr ratio within the tree and within the orchard is explained in light of the ⁸⁷Sr/⁸⁶Sr ratios of the soil. This ⁸⁷Sr/⁸⁶Sr variability within orchards does not preclude its use as a geographical tracer; however, this aspect should be evaluated to correctly design a sampling campaign or to generalize the results.

Influence of Chemical and Physical Variables on 87Sr/86Sr Isotope Ratios Determination for Geographical Traceability Studies in the Oenological Food Chain

This study summarizes the results obtained from a systematic and long-term project aimed at the development of tools to assess the provenance of food in the oenological sector. 87Sr/86Sr isotope ratios were measured on a representative set of soils, branches, and wines sampled from the Chianti Classico wine production area. In particular, owing to the high spatial resolution of the 87Sr/86Sr ratio in the topsoil, the effect of two mill techniques for soil pretreatment was investigated to verify the influence of the particle dimension on the measured isotopic ratios. Samples with particle sizes ranging from 250 to less than 50 µm were investigated, and the extraction was performed by means of the DIN 19730 procedure. For each sample, the Sr isotope ratio was determined as well. The obtained results showed that the 87Sr/86Sr ratio is not influenced by soil particle size and may represent an effective tool as a geographic provenance indicator for the investigated product.