Volatile and odour-active compounds of air-classified faba bean fractions

International audienceFaba bean is an interesting alternative to animal proteins due to environmental, food functionality and nutritional benefits. Air-classification is a dry process based on the separation of the coarse fraction (starch fraction) and the fine fraction (protein fraction). Volatile compounds, and especially odour-active ones, contribute to pulse’s off-notes that decrease the consumer acceptability. Degradation of amino acids, carotenoid and free fatty acid oxidations are the origins of these molecules and happen during plant growth, storage and transformation stages. Today, a little is known about volatile and mainly odour-active compounds of faba beans. To better understand the volatiles involved in faba bean off-notes, different cultivars and air-classified fractions (flour, starch and protein) were studied. SAFE (Solvent-Assisted Flavour Evaporation) extraction, GC-MS (Gaz Chromatography-Mass Spectrometry) and GC-O (GC-Olfactometry) methods were conducted. A total of 147 volatile compounds were identified by GC-MS whose origin was related to the literature for 67 of them. Free fatty acid oxidation was common to all fractions, and especially in the protein ones, correlated to important LOX (lipoxygenase) activity. However, one cultivar presented greater quantity of volatiles from amino acid breakdown that suggested an intense endogenous secondary metabolism or microorganism contamination. Then, 35 odour-active compounds where identified by GC-O and 10 new attributes were highlighted for the first time in faba bean. Protein fractions with greater quantity of volatiles were also characterized by important detection frequency. This approach could be extended to identify cultivars and processes that limit the presence of off-notes in faba bean and pulses