Combining sensory profiling and metabolomic approach to better understand the origins of bitter perception in faba bean (Vicia faba L. minor) fractions

Faba beans are promising alternatives to animal proteins due to environmental, food functional and nutritional benefits. However, they are characterised by off-flavours, notably off-notes and bitterness. Research on pulses and pulse-based products has largely focused on the involvement of volatile compounds in off-notes whereas the molecules responsible for pulse bitterness have not been studied as much. To better understand the role of non-volatile compounds in faba bean bitterness, different cultivars and air-classified fractions (flour, starch and protein) were investigated for their taste properties. Firstly, 21 trained panellists evaluated the bitter intensity of gels containing faba bean fractions. Bitter differences were highlighted according to the type of fractions and cultivars. Secondly, an untargeted metabolomics approach based on UHPLC-DAD-HRMS (ultra-high-performance liquid chromatography-diode array detector-high-resolution mass spectrometry) analysis was carried out for profiling the non-volatile content of the fractions. Thirdly, the sensory data was correlated with the metabolomic data resulting in the tentative identification of 42 phytochemical compounds (mainly alkaloids). Fourthly, the bitterness of highlighted compounds was studied using an in vitro cellular-based assay. Linking sensory attributes with the chemical content of pulse-based products allows to target compounds responsible for bitterness to propose strategies improving their flavour and the consumer acceptability.