Proteomic/peptidomic profile and <i>Escherichia coli</i> growth inhibitory effect of <i>in vitro</i> digested soya protein

Plant proteins contain bioactive peptides with functional properties and physiological activities. In the present work, the bioactive peptides produced during <i>in vitro</i> gastrointestinal digestion of soya protein isolate were investigated. Protein samples were subjected to simulated gastrointestinal digestion with a generation of permeate (&lt;3 kDa) and retentate (&gt;3 kDa) fractions. The permeate was analysed by nano-liquid chromatography electrospray ionisation tandem mass spectrometry (LC-nano ESI MS/MS) using a shotgun peptidomic approach, and the retentate was further digested with trypsin and analysed using a shotgun proteomic approach. Based on protein profile observed, the retentate was further tested for its potential antimicrobial activity by evaluating the inhibitory effect on <i>E. coli</i> growth. In the present study the peptidomic/proteomic characterisation of permeate and retentate fractions revealed the presence of bioactive peptides and proteins associated with antioxidant, ACE-inhibitory, anti-hypertensive and antimicrobial activities. The presence of potentially antimicrobial proteins in the retentate fraction is supported by a marked <i>E. coli</i> F18+ growth inhibitory activity of the same fraction. In particular, the growth inhibitory effect was significant from one until six hours of incubation with 0.65–2.6 mg/ml of <i>in vitro</i> digested soya. The obtained data confirmed that soya-based supplements may have potential beneficial effects after human consumption, and they may be re-cycled for animal nutrition in line with the circular economy concept.HighlightsSoya-based supplements are relevant sources of bioactive molecules.Soya based supplements could be re-cycled for animal feeding considering the circular economy concept. Soya-based supplements are relevant sources of bioactive molecules. Soya based supplements could be re-cycled for animal feeding considering the circular economy concept.