Time: Thursday, 19/June/2025: 11:00am - 11:40am Session Chair: Eva de Rijke Session Chair: Simon Douglas Kelly |
Location: 5161.0151 Bernoulliborg, Nijenborgh 9, 9747 AG Groningen |
Tracking tomato processing with stable isotopes: a study on fractional composition and authenticity
1National Research and Development Institute for Cryogenic and Isotopic Technologies ICSI Rm. Valcea, Romania; 2Doctoral School of Chemical Engineering and Biotechnologies, U.N.S.T. Politehnica of Bucharest
The isotopic fingerprint of food products serves as a crucial tool for assessing traceability and authenticity, offering insights into raw material origin and transformation processes. This study examines the stable isotope composition of carbon (¹³C), nitrogen (¹⁵N), oxygen (¹⁸O), and hydrogen (²H) in tomatoes and their derived fractions at different processing stages during their transformation into tomato passata (Brix ~36). The objective was to assess the persistence of isotopic signatures throughout processing and establish a direct isotopic link between raw material and final product. Six experimental trials were conducted using different tomato varieties, with isotopic ratios measured via Isotope Ratio Mass Spectrometry (IRMS). Despite significant water loss and concentration effects, isotopic values remained within a characteristic range, confirming the retention of the original raw material’s isotopic fingerprint. The δ¹³C values of bulk tomatoes ranged from -26.58‰ to -28.56‰, while δ¹⁵N remained stable across processing stages. Expected variations in δ¹⁸O and δ²H, due to evaporation, retained a discernible pattern linked to the initial material. A detailed isotopic analysis of tomato fractions, including pectin, pulp, sugar, and organic acids, further confirmed isotopic stability. δ¹³C in pectins shifted slightly from -28.04‰ to -25.45‰ in juice and from -29.21‰ to -25.56‰ in passata, while δ¹⁵N remained relatively constant. The pulp fraction exhibited minor isotopic shifts, with δ¹³C ranging from -29.05‰ to -27.42‰ in juice and from -28.46‰ to -26.63‰ in passata. δ¹³C in sugars and organic acids remained stable, demonstrating minimal alteration during processing. These findings highlight the robustness of stable isotope analysis as an effective tool for verifying the authenticity of processed tomato products. The observed isotopic stability across different tomato fractions supports the use of δ¹³C, δ¹⁵N, δ¹⁸O, and δ²H as reliable markers for traceability, reinforcing their role in food authentication and quality control strategies.
Latest applications of the LC-co-IRMS for food and dietary supplements authentication
1Technology Transfer Center, Fondazione Edmund Mach, Italy; 2Research and Innovation Center, Fondazione Edmund Mach, Italy
The LC-co-IRMS represents an innovative technique based on the oxidation in acid conditions of all the carbon-based compounds of a sample mixture, previously separated from each other through an appropriate analytical column. Since its introduction in the market in 2004, the LC-co-IRMS has been used to analyse various matrices [1]. Nevertheless, the potential of this techniques is still far from being fully exploited. In this work, we presented some of the latest LC-co-IRMS applications that our group developed for traceability purposes.
In a recent study, the LC-co-IRMS was applied to check for the fraudulent addition of exogenous sugars to Italian authentic wine must. A database of about 100 samples from 16 different Italian regions was considered to set reference values for the carbon isotopic ratio (δ13C) of glucose and fructose in this matrix [2].
Besides sugars, organic acids have also been considered. The addition of biosynthetic citric acid obtained though the fermentation of cheap starting materials like cane sugar by the fungus Aspergillus Niger was detected in matrices such as tomato sauce, lemon and orange juice.
Finally, dietary supplements and drugs have also been studied. Levodopa is an amino acid prescribed for Parkinson disease. Natural levodopa can be extracted from plants like the Mucuna pruriens, but cheaper analogues can be chemically synthesised or biochemically obtained from the fermentation of sugars by various fungi [3]. The LC-co-IRMS led to the characterisation of the different levodopa sources, pointing out the possibility to detect fraudulent additions of the biochemical active principle to products declared as natural.
[1] Perini, M.; Bontempo, L. Trends in Analytical Chemistry 2022, 147, 116515. doi.org/10.1016/j.trac.2021.116515
[2] Perini, M.; Pianezze, S.; Guardini, K.; Allari, L.; Larcher, R. Molecules 2023, 28, 1411. doi.org/10.3390/ molecules28031411
[3] Min, K.; Park, K.; Park, D.H.; Yoo, Y.J. Appl Microbiol Biotechnol 2015, 99, 575-584. doi: 10.1007/s00253-014-6215-4.