Compound-specific Isotope Ratio Analysis for Authentication of High-value Plant Products

Research output: Book/ReportPh.D. thesisResearch

The retail sales of organic food are continuously increasing worldwide. The high demand and premium prices put organic plant products at high risk of food fraud. New analytical methods are urgently needed to ensure the authenticity and integrity of organic production. Stable isotope ratio mass spectrometry is an established and widely applied tool in plant and food forensic sciences. However, recent studies have demonstrated a limitation of traditional bulk tissue stable isotope markers to distinguish fully between conventionally and organically produced plants. Therefore, the PhD project aimed to develop novel compound-specific stable isotope techniques based on analysis of plant oxyanions and use those for authentication of organically grown plants. A new method was developed and it was based on stable isotope analysis of oxygen in plantderived sulphate. The method was implemented and validated on conventional and organic crops from field trials and retail case studies. Next, the key mechanisms determining the stable isotope signatures of plant-derived sulphate were investigated in greenhouse and soil incubation studies. Mechanisms controlling the known bulk tissue stable isotope markers were also examined in hydroponically grown plants, which were deprived in essential plant nutrients. The field and case studies showed that sulphate-based stable isotope analysis was able to discriminate conventional and organic crops and was applicable in different species, across geographical locations, and microclimates. The mechanistic studies revealed that the isotopic signature of soil water and fertilization type were the major factors determining the oxygen stableisotope signature of plant sulphate. The hydroponic experiment showed that selected macronutrient deficiencies can significantly bias the plant bulk tissue stable isotope signatures.The PhD project documented that stable isotope analysis of plant sulphate is a powerful tool for authenticity testing of organic vegetables. Despite the shown limitations of bulk stable isotope markers, they can complement the compound-specific approach and increase the classification power. The novel analytical approach is ready for accreditation and industrial application in the food sector, and it has the potential to protect producers and consumers of organic plant products from food fraud activities.
Original languageEnglish
PublisherDepartment of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen
ISBN (Print)978-87-7209-317-8
Publication statusPublished - 2019

ID: 234697085