Screening of wine industry by-products as a source of bioactive peptides: Fractionation, in vitro antihypertensive activity and peptidomics analysis.

The suitability of grape pomace and wine lees protein isolates as a source of bioactive peptides with antihypertensive activity was evaluated through hydrolysis with different proteolytic enzymes. Peptides were initially fractionated by ultrafiltration. The determination of the angiotensin-converting enzyme inhibitory activity evidenced that hydrolysates of Flavourzyme from grape pomace and of Alcalase from wine lees showed higher bioactivities. The fractions <3 kDa of these hydrolysates were further purified by semipreparative reversed-phase liquid chromatography. The peptidome of the fractions showing the highest angiotensin-converting enzyme inhibitory activities was characterised by nano-liquid chromatography-Orbitrap tandem mass spectrometry. The analysis of the chemical features of identified peptides like hydrophobicity and the frequency of angiotensin-converting enzyme inhibitory-active di-, tri- and tetrapeptide motives was associated with the antihypertensive activity. The peptides GPCKFYYGK, FSSFYYGK and YYGKF, among others, appear to contribute significantly to the antihypertensive activity of the hydrolysates.