Thyme (Thymus vulgaris) has been demonstrated to extend the shelf-life of food products, being also a potential source of bioactive compounds. The aim of this research was to optimize the ultrasound assisted extraction employing β-cyclodextrin aqueous solutions as no-contaminant technology and Response Surface Methodology to obtain thyme extracts with the maximum antioxidant capacity. The optimal extraction conditions were: a solution of β-ciclodextrin 15 mM, an ultrasonic treatment time of 5.9 min at a temperature of 36.6 °C. They resulted in an extract with a polyphenolic content of 189.3 mg GAE/mL, an antioxidant activity (DPPH) of 14.8 mg GAE/mL, and ferric reducing/antioxidant power (FRAP) of 3.3 mg GAE/mL. Interestingly, the extract demonstrated to inhibit the production of Maillard browning products and can be considered a potential antiglycant agent. The obtained data is important for developing eco-friendly technologies in order to obtain natural antioxidant extracts with a potential inhibitory capacity of Maillard glycation reaction.

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Propidium monoazide (PMA) is a selective nucleic acid intercalating dye that can be combined with real‐time PCR (qPCR) in order to evaluate cell viability in food samples. The aim of the present work was to evaluate PMA‐qPCR to detect and quantify viable STEC cells in beef burgers using stx2 as target gene. First, it was determined that 100 µM of PMA could inhibit qPCR signal from non‐viable cells and had no influence on the amplification of different concentrations of viable cells. Then, it was shown that PMA efficiently distinguished between different log cfu of viable cells in presence of a high concentration of non‐viable cells, both in culture and in beef burger homogenates. Finally, it was determined that PMA could distinguish between viable and non‐viable cells within the same log cfu in beef burger homogenates. PMA‐qPCR effectively detected and quantified viable STEC cells in culture and in beef burger homogenates. Novelty impact statement The main achievement of this work is that we demonstrate PMA‐qPCR could not only detect, but also quantify viable STEC cells targeting stx2 gene, even in the presence of a high concentration of non‐viable STEC cells in a complex matrix as beef burgers. This methodology can be used to assess effectiveness of antimicrobial treatments to reduce STEC contamination in meat products more rapidly and with less pathogenic residues than conventional methods.