Inhibitory mechanism of quercetin against the formation of 5-(hydroxymethyl)-2-furaldehyde in buckwheat flour bread by ultra-performance liquid chromatography coupled with high-resolution tandem mass spectrometry.

Ultra-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC-HRMS/MS) was employed to investigate the inhibitory mechanism of quercetin against the formation of 5-(hydroxymethyl)-2-furaldehyde (HMF) in buckwheat flour bread. The HMF and HMF precursors (3,4-dideoxyglucosone-3-ene (3,4-DGE), 3-deoxyglucosone (3-DG), or fructofuranosyl cation dehydration products (FCDPs)) adducts of quercetin were detected in buckwheat flour bread, with the trapping of these compounds by quercetin to form corresponding adducts with HMF or its precursors in 1:1, 1:2, 1:3, and 1:4 ratios (where "1" refers to quercetin in all cases). The structures of these adducts were elucidated by UPLC-HRMS/MS. Carbohydrate module labeling (CAMOLA) techniques and the labelled quercetin in model reactions were utilized to further confirm the inhibitory mechanism. Effects of baking temperature and time on the HMF inhibition rate were investigated in wheat flour bread, and a maximum inhibition rate of 86.0% was obtained with the baking of wheat flour bread (with the added quercetin concentration of 1.90mg/g) at 160°C for 30min.