Characterisation of off-flavour compounds and their sensory impact on Lupinus angustifolius L.: Special emphasis on volatile markers of green, grassy, and beany aroma notes and bitter taste.

Abstract

Volatile organic compounds (VOCs) across five varieties of Lupinus angustifolius L. were quantified using headspace solid-phase microextraction assisted gas chromatography orbitrap mass spectrometry (HS-SPME-GC-Orbitrap-MS), and alkaloids were analysed using liquid chromatography mass spectrometry (LC-MS) with their sensory impact assessed through a trained panel. To our knowledge, this is the first systematic comparison of off-flavour profiles across multiple L. angustifolius varieties grown in Western Australia under different sowing conditions. Two-way analysis of variance (ANOVA) revealed that quinolizidine alkaloids (QAs) and VOCs in L. angustifolius were regulated by interactions between the sowing time and variety. Partial Least Squares regression (PLS-R) indicated that PBA Jurien exhibited stronger bitterness and a 'green/grassy' aroma, whereas Tanjil had a stronger beany aroma. Kalya and Mandelup showed lower contribution to undesirable sensory notes. Pearson correlation analysis revealed a weak positive, statistically significant relationship between 'green/grassy' aroma and specific lipoxygenase (LOX) activity across L. angustifolius varieties, whereas no significant correlation was observed between 'beany' aroma and specific LOX activity. Lupanine showed a strong positive correlation with specific LOX activity and a moderate positive association with bitterness. This study provides insights into screening L. angustifolius varieties with reduced 'beany', 'green/grassy' aromas and bitterness for future human food applications.