Enhanced functional characteristics and digestibility of blends of hemp protein hydrolysate and pea protein isolate

Plant-based proteins show poor functional properties and when a balanced source of amino acids is required, it cannot be provided only by a single source of plant-based protein. This study aims to enhance the functional and digestibility properties of hemp seed meal (HSM) protein by hydrolyzation (HPH) through ultrasonication and enzymatic treatment. The blending of HPH with pea protein isolate (PPI) was conducted to improve the amino acid profile. During ultrasonication, the protein content was significantly affected (p < 0.05) by ultrasonication time and solid-to-solvent ratio but not by the amplitude. Degree of hydrolysis was significantly (p < 0.05) affected by all three variables. Optimal hydrolysate was prepared by ultrasonication at 80% amplitude for 10 min and solid-to-solvent ratio of 1:30, with a protein content of 64.57% and a degree of hydrolysis (DH) of 6.25%. Under these conditions, papain treated HPH exhibited an increase in protein concentration (84.2%) and DH (17.3%). The blend of HPH and PPI in the ratio of 1:1 showed improved protein content (85.5%) with significant (p < 0.05) increase in solubility (72.8% at pH 7). This blend showed a good emulsifying activity index (33.4 m²/g) emulsifying stability (35.3 min), oil holding capacity (2 g/g), water holding capacity (1.8 g/g), foaming capacity (195.8%), and foaming stability (85.2%). This blend also displayed a balanced amino acid profile, with methionine and lysine contents of 1.63 mg/g and 5.88 mg/g, respectively. The blend of PPI:HPH (1:1) showed integration of HPH into the PPI matrix, due water bridging between protein particle as observed by scanning electron microscopy (SEM). The amide I at 1627.6 cm⁻¹ in HSM shifted to 1633.7 cm⁻¹ in HPH and amid II at 1518.7 cm⁻¹ in HSM shifted to 1535.3 cm⁻¹ in HPH indicating a change in secondary structure of HSM due to ultrasonication and enzymatic hydrolysis. In Vitro protein digestibility of 1:1 blend was also higher compared to other samples. The blend of HPH and PPI blend have good potential for creating nutritionally enhanced and functionally superior plant-based food products.