Stable Carbon and Nitrogen Isotope Ratios of Red Bell Pepper Samples from Germany, The Netherlands, and Spain

Bell pepper is one of the most cultivated crops in the world. By means of δ13C and δ15N values (‰), red bell peppers from Germany, The Netherlands, and Spain could be distinguished from each other. German fruits cultivated under greenhouse conditions were extremely depleted in 13C with δ13C values for fatty acids of partly less than −50‰. The strong depletion in 13C was in accordance with the use of biomethane-derived CO2 as growth regulator in the greenhouses. Seasonal variations in the δ13C values (‰) of German samples were tentatively assigned to varying CO2 enrichment during the annual production cycle. δ13C values (‰) of Dutch samples also correlated with greenhouse production, whereas Spanish samples most likely originated from open field cultivation. Additionally, the use of color measurement as a tool for presorting the samples was investigated in order to slim the scattering ranges of δ13C and δ15N values (‰) for clearer differentiation.