Compound-Specific δ¹⁵N and δ¹³C Analyses of Amino Acids for Potential Discrimination between Organically and Conventionally Grown Wheat

Abstract

We present a study deploying compound-specific nitrogen and carbon isotope analysis of amino acids to discriminate between organically and conventionally grown plants. We focused on grain samples of common wheat and durum wheat grown using synthetic nitrogen fertilizers, animal manures, or green manures from nitrogen-fixing legumes. The measurement of amino acid δ(15)N and δ(13)C values, after protein hydrolysis and derivatization, was carried out using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Our results demonstrated that δ(13)C of glutamic acid and glutamine in particular, but also the combination of δ(15)N and δ(13)C of 10 amino acids, can improve the discrimination between conventional and organic wheat compared to stable isotope bulk tissue analysis. We concluded that compound-specific stable isotope analysis of amino acids represents a novel analytical tool with the potential to support and improve the certification and control procedures in the organic sector.

Quantifying terrestrial carbon in freshwater food webs using amino acid isotope analysis: Case study with an endemic cavefish

“…CO 2 ) enters biological systems. Using this search protocol, we aggregated 121 data points (Appendix ) comprising 78 allochthonous carbon sources (Fogel & Tuross, ; Jarman et al, ; Larsen et al, ; Paolini, Ziller, Laursen, Husted, & Camin, ; Thorp & Bowes, ) and 43 autochthonous carbon sources (Larsen et al, ; Scott et al, ; Thorp & Bowes, ). Geographically, origins of non‐cultured producer samples include Africa [i.e.…”

Multi‐isotopic signatures of organic and conventional Italian pasta along the production chain

“…This has generated additional information regarding the fertilizer source and has enabled discrimination of plants grown with synthetic fertilizers and legume‐based green manures. In addition, gas chromatography coupled to isotope ratio mass spectrometry (GC‐c‐IRMS) for the analysis of δ 15 N and δ 13 C of amino acids was recently successfully applied to Danish bread wheat and Italian durum wheat . Another solution is to combine the isotopic ratio of N with those of other bio‐elements, such as H, C, O and S, as it has been performed for some organic fruits .…”

δ15N from soil to wine in bulk samples and proline

“…Nitrogen stable isotope ratio analysis has been shown to be a useful tool for characterizing the geographical origin of food products in combination with other isotopic parameters and is commonly used to verify the management system applied in agriculture …”

“…Traditionally, stable isotope analysis has relied on measurement of bulk products or specific components after proper extraction, but emerging methods aimed at direct analysis of individual chemical compounds provide a means of obtaining a more in‐depth understanding . Recently, gas chromatography combustion isotope ratio mass spectrometry (GC‐c‐IRMS) has been used to examine the effects of fertilization practices on the δ 15 N and δ 13 C values of individual amino acids in wheat and durum wheat to discriminate between organically and conventionally grown plants . Amino acids in grapes and wines have various origins, and their nature and concentration influence the growth of yeast during fermentation, the fermentation rate and the production of aromatic compounds .…”