The inclusion of (+)-pinoresinol from flaxseed extracts into β-cyclodextrin elucidated by liquid state NMR techniques.

(+)-Pinoresinol (PIN) is a relevant lignan found in flaxseed-derived extracts, but its direct NMR identification in complex food matrices is difficult because of signal overlap and low concentration. In this work, we propose an NMR-based strategy for the selective identification of PIN directly in a multicomponent flaxseed extract. The method combines 1H NMR spectral pattern recognition, quantitative 31P NMR analysis of phenolic hydroxyl groups, and selective spiking experiments. Structural validation was obtained by characterizing the pure PIN/β-cyclodextrin (β-CD) inclusion complex through chemical shift variation analysis, ROESY, and DOSY, which supported a predominant 1:1 stoichiometry in solution. The binding constant was calculated from UV-Vis spectra applying the Benesi-Hildebrand approach. The agreement between the isolated system and the crude extract indicates supramolecular recognition of PIN within the natural matrix. Overall, this study provides an NMR-based approach for the identification of minor lignans in food-derived extracts and supports its application to complex food systems.