Characterisation of volatile compounds of lupin protein isolate‐enriched wheat flour bread

Abstract

The influence of lupin protein isolate (LPI) on the volatile fraction of wheat flour (WF) bread was investigated. Headspace solid-phase microextraction technique (HS-SPME) coupled to the gas chromatography–mass spectrometry (GC–MS) analysis was applied to characterise volatile compounds of both crust and crumb. In a preliminary sensory experiment, LPI was found to have a modifying effect on the odour of WF-bread. The most important odorants of WF and LPI-containing wheat flour (LWF) breads were evaluated on the basis of detection frequency analysis. Fifty three compounds were detected by more than five judges, ten of which were detected only in LWF bread. The most important compounds of LPI-containing crumb and crust were vinylpyrazine, hexanal, 2-propylpyrazine, 2-octenal, 2,3-butanedione, 2,5-dimethylpyrazine, non-identified compounds with green, mushroom-like or pleasant odour and pyrazines. Their presence was attributed either to oxidative degradation of fatty acids or thermal reactions. Most of these compounds contributed to the aroma character of LPI-bread with green, earthy, malty, buttery and roasted notes.