Faba bean and pea protein ingredients: Endogenous lipid accumulation and lipid oxidative state

Pulses such as faba bean and pea are a promising source of proteins in the current protein transition. For their use in food products, they are processed into protein ingredients through dry or wet fractionation routes. The use of these ingredients is currently hampered by their inherent off-flavours, partly arising from lipid oxidation. In this study, both commercial and pilot-scale-produced faba bean and pea protein ingredients were used to determine their endogenous lipid profile, as well as the lipids' oxidative status. All protein ingredients contained considerable amounts of endogenous lipids compared to the raw material (4.4-6.6 g/100 g dry matter for concentrates and 7.4-7.5 g/100 g dry matter for isolates), and more than half these lipids were phospholipids. In addition, minor lipophilic compounds (tocopherols, carotenoids) were present in substantial amounts (240-2700 μg/g lipids) that varied both with the seed cultivar or growing conditions and with the seed-to-ingredient processing method. The endogenous lipids had undergone oxidation, as high and highly variable levels of hydroperoxides were found (2.7-57 μmol/g lipids). Yet, levels of secondary lipid oxidation markers were fairly low, and no strong occurrence of off-flavour associated volatiles, e.g., hexanal, was detected. Nonetheless, considering the high initial hydroperoxide concentration, it is expected that these off-flavours can quickly be formed upon hydroperoxide decomposition if these ingredients are applied in typical food matrices, such as plant-based dairy alternatives. These results substantiate the origin of lipid-derived off-flavours in pulse protein applications.