Introducing dried spot techniques in food characterization: The case of red wine.

Food quality, interrogated by analytical methods, is a prerequisite of modern societies' well-being. However, analysis is greatly compromised at the sampling and sample preparation stages, which are typically resource-intensive and tedious. Dried spot microsampling on paper cards, used almost exclusively for dried blood spots (DBS) in biomedical settings, offers noteworthy advantages to conventional techniques, almost eliminating sample preparation amid easy on-site sampling. Moreover, it involves minute sample size and transportation by regular post, relieved from bulk sample requirements and questionable transfer and storage conditions. Dried spot techniques could thus provide an attractive solution to existing challenges for holistic food quality assessment, yet they remain unwarrantedly unexplored in this field. The present work introduces dried spot sampling of food commodities, or Food-DS, as an alternative format in food characterization, utilizing untargeted LC-HRMS as a powerful metabolite profiling tool. Using red wine as a proof-of-concept, an optimized workflow was developed for volumetric sampling on standard DBS cards followed by automated extraction and was successfully compared to conventional techniques. Various aspects were optimized for enhanced sensitivity and metabolite coverage, including spot extraction parameters and, notably, extraction solvent type, assisted by the dereplication results. The possibility of remote sampling by non-trained users, in conjunction with automated card processing, highlights the potential of the proposed workflow to promote accessible and cost-effective food analysis. This study is envisioned to serve as a basis for the integration of dried spot techniques in food characterization towards more convenient and resource-efficient quality assessment, minimizing logistical constraints.