Development and implementation of stable isotope ratio analysis in bulk products and sub-components to ensure food traceability

Nowadays, objective assessment of food authenticity has become of paramount importance with an increasing demand for analytical methods able to provide proof of origin and prevent food adulteration. In order to achieve this scope, the European Union has reinforced control activities and investigated new markers able to support food characterisation and geographical traceability. Stable isotope ratio analysis of so-called bioelements such as hydrogen, carbon, oxygen, nitrogen and sulphur has been applied since the 1990s for food authenticity control of different premium products. Application of isotopic composition is based on evidence that isotopic signature is affected by various environmental factors such as photosynthetic and nitrogen cycles, pedological characteristics of soils, agricultural practices, botanical origin, geographical origin and climatic or hydrological conditions. In this study, isotope ratio mass spectrometry methods were developed to characterise and determine the authenticity of cereal crops, pasta, wine, balsamic vinegar, oenological tannins and extra-virgin olive oils. In particular, the isotopic variability measured along the Italian production chain of pasta allowed good discrimination in relation to geographical provenance. \u3b42H, \u3b418O and \u3b413C were shown to be significantly correlated to geographical factors (e.g. longitude), whereas \u3b415N and \u3b434S were affected by geology and fertilization practices. The measurement of amino acid \u3b415N and \u3b413C values improved the discrimination between conventional and organic wheat compared to stable isotope ratio analysis of bulk. Variability of \u3b415N value was checked along the entire oenological chain for the first time. The study included evaluation of the effect of the fermentation process using different types of yeast, the addition of nitrogen adjuvants and ultrasound lysis simulating wine ageing. Despite nitrogen isotope fractionation observed from soil to wine through plant, the \u3b415N value of proline conserves the nitrogen isotopic fingerprint of the growing soil and can therefore be used as additional isotopic marker to trace the geographical origin of wine. The same analytical approach, when applied to commercial tannins samples, made it possible to characterise them based on the botanical origin. The \u3b413C values were shown to be significantly more negative in tannins from grapes, tea and acacia and less negative in tannins from oak. Furthermore, stable isotope ratios \u3b42H, \u3b413C of acetic acid and \u3b418O of water were investigated in \u201caceto balsamico di Modena IGP\u201d (ABM) samples. No isotopic variation was observed along production chain of ABM, providing experimental evidence that such analytical parameters, used routinarely for wine, can be used also for ABM in authenticity studies. Finally, \u3b42H, \u3b413C and \u3b418O of extra-virgin olive oils were analysed in bulk samples and compounds, specifically in fatty acids. The results showed that bulk analysis was able to discriminate between some different countries on the basis of specific geo-climatic conditions. Moreover, both \u3b413C and \u3b42H values of main fatty acids allowed a good discrimination between European and non-European extra-virgin olive oils. To conclude the methods developed for the specific considered commodities can be proposed as suitable tools for the detection of mislabelling and for consumer protection, demonstrating that isotopic analysis can effectively contribute towards distinguishing the authenticity of commercial sample