Characterization of L-theanine in tea extracts and synthetic products using stable isotope ratio analysis

Matteo Perini ^a, Silvia Pianezze ^a,d,*, Luca Ziller ^b, Federica Camin ^b,c

a Technology Transfer Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38098, San Michele all'Adige, Italy

b Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38098, San Michele all'Adige, Italy

c Department of Cellular, Computational and Integrative Biology, University of Trento, Centre Agriculture Food Environment C3A, Via E. Mach 1, 38098, San Michele all'Adige, Italy

d Department of Agricultural and Environmental Sciences, University of Udine, Via Sondrio 2A, 33100, Udine, UD, Italy

L-theanine involves a great number of health benefits and dietary supplements containing this molecule are becoming increasingly popular. There is, therefore, a growing need to find ways to discriminate between natural L-theanine extracted from tea leaves and the cheaper, synthetic one obtained using specific bacterial enzymes. A first attempt of stable isotope ratio analysis characterization of the possible synthetic adulterant L-theanine (d13C of -14.3 ± 1.5‰), obtained from vegetable substrates with C4 photosynthetic cycle, and of the more expensive natural L-theanine (d13C of -24.4 ± 1.3‰), extracted from Camellia sinensis plants with C3 photosynthetic cycle, is reported here.

Keywords: Authentication, Carbon and nitrogen stable isotope ratios, IRMS, L-theanine, Tea

https://doi.org/10.38212/2224-6614.3249