Microencapsulation of bayo bean (Phaseolus vulgaris) protein hydrolysate with inhibitory activity on angiotensin-I converting enzyme through freeze-drying

The aim of this study was to obtain microcapsules of a bayo bean protein hydrolysate (BBPH) with antihypertensive activity using Eudragit® L 30 D-55 as wall material (EGLD) through freeze-drying processing. The BBPH was obtained using sequential pepsin-pancreatin enzymatic system. The ACE-I inhibitory activity was measured using tripeptide hippurylhistidyl leucine (HHL) as model peptide. Three microcapsule formulations were prepared containing BBPH and EGLD at ratios of 1:20, 1:4 and 1:1, respectively. The physicochemical characteristics of microcapsules were evaluated by optical (OM) and scanning electronic microscopy (SEM), confocal laser scanning microscopy (CLSM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). ACE-I inhibitory activity of BBPH was IC₅₀=0.42 mg/mL. All microcapsules showed irregular shapes. The BBPH was distributed homogeneously in all formulations. The DSC and XRD analysis revealed a uniform dispersion of the BBPH and partially crystalline structures of EGLD and BBPH. The FT-IR confirmed the chemical stability of BBPH in the microcapsules. In conclusion, the EGLD microcapsules containing BBPH were prepared successfully by freeze-drying processing.