Proximate composition, peptide characterization and bioactive properties of faba bean blanching water

Faba bean (Vicia faba L.) offers a rich nutritional profile with high protein content and abundant vitamins and minerals. Processing of faba beans for freezing requires blanching, yielding liluva (legume processing water), possibly containing leached macronutrients, with potential for upcycling. Past evidence has shown that legume processing water may be high in protein. Peptides generated from faba bean proteins during processing have been shown to have bioactivity and can, for example, inhibit HMG-CoA reductase. HMG-CoA reductase is rate-limiting in the biosynthesis of cholesterols and high cholesterol increases the risk of cardiovascular diseases. Thus, this study examined the composition of legume blanching water, analysed the peptides resulting from in vitro digestion and assayed HMG-CoA reductase inhibitory activity of liluva from faba beans sourced from two farms in Canterbury, New Zealand. Results showed that the blanching water contained around 1.7 g/100 mL solid content. These solids were approximately 30 % protein, 12 % water-soluble carbohydrates, 4 % dietary fibre, and 0.17 % ash. Mineral analysis showed high levels of potassium in macro minerals and zinc in trace minerals. Free amino acid analysis revealed high levels of arginine, alanine, asparagine, and glutamic acid, and low levels of methionine and tryptophan. Mass spectrometry analysis identified 111 and 72 endogenous peptides in farm 1 and 2 raw samples, respectively. Most of these peptides were derived from tripeptidyl-peptidase II and subtilisin-like protease. To understand potential bioactivity of these peptides, peptides were also analyzed after in vitro digestion. The resulting identified peptides indicated in silico predicted bioactivities such as anti-thrombotic, antioxidative, ACE dipeptidyl peptidase -III and -IV inhibition and HMG-CoA reductase inhibition activities. Further validation of the faba bean blanching water after in vitro digestion demonstrated approximately 67 % inhibition of HMG-CoA reductase activity, suggesting potential hypocholesterolemic properties. These findings suggest that faba bean blanching water may serve as a sustainable and functional ingredient with potential cholesterol-lowering effects in food production.