LC-MS/MS quantitation of α-amylase/trypsin inhibitor CM3 and glutathione during wheat sourdough breadmaking.

AIMS This study aimed to quantify α-amylase/trypsin inhibitor (ATI) CM3 and glutathione (GSH) during wheat sourdough breadmaking. METHODS AND RESULTS Breads were made with two wheat cultivars and fermented with Fructilactobacillus sanfranciscensis, F. sanfranciscensis ΔgshR or Latilactobacillus sakei; chemically acidified and straight doughs served as controls. Samples were analysed after mixing, after proofing and after baking. GSH and CM3 were quantified by multi-reaction-monitoring-based methods on an LC-QTRAP mass spectrometer. Undigested ATI extracts were further examined by SDS-PAGE. CONCLUSIONS GSH abundance was similar after mixing and after proofing but increased after baking (p < 0.001), regardless of fermentation. In breads baked with cv. Brennan, the samples fermented with lactobacilli had higher GSH abundance (p < 0.001) than in the controls. CM3 relative abundance remained similar after mixing and after proofing but decreased after baking (p < 0.001) across all treatments. This trend was supported by the SDS-PAGE analysis in which ATI band intensities decreased after baking (p < 0.001) in all experimental conditions. The overall effect of baking exerted a greater effect on the abundances of GSH and CM3 than fermentation conditions. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first report to quantify ATI over the course of breadmaking by LC-MS/MS in sourdough and straight dough processes.