Influence of hemp protein hydrolysates on the textural, thermal, rheological, and structural properties of corn starch with varying amylose content

Abstract

Over the past decades, researchers have investigated the changes in physical, chemical, and nutritional properties of starch blended with various biomolecules. Hemp seed meal is a sustainable byproduct of hempseed oil extraction, and there is limited research on the use of hemp protein hydrolysates, prepared from this hemp seed meal, as a food ingredient. This study investigated the physicochemical properties of hemp protein hydrolysates (HPH) and corn starch complexes using corn starch with varying amylose contents: waxy corn starch (WCS, 1% amylose), normal corn starch (NCS, 27% amylose) and high-amylose corn starch (HACS, 68% amylose). The addition of the HPH to the starch significantly modified the textural properties of starch gels, particularly enhancing elasticity and hardness in WCS and NCS, and increasing adhesiveness in NCS and HACS. Notable effects were observed with 20% HPHP (HPH hydrolyzed by pepsin) on WCS elasticity, 10% HPHB (HPH hydrolyzed by bacterial protease) on WCS hardness, and 20% HPHB on WCS adhesiveness. Particle size distribution indicated substantial granule size increases, especially in HACS. FT-IR analysis revealed shifts in absorption peaks, suggesting altered hydrogen bonding interactions without new functional groups. The addition of protein hydrolysates further amplified the thermal properties of starch, particularly in HACS. Rheological properties varied, with increased storage (G′) and loss (G") moduli in NCS-HPH mixtures and general decreases in WCS-HPH and HACS-HPH. The findings of this study highlight the potential of hemp protein hydrolysates as novel food ingredients when combined with carbohydrates, offering improved functional properties and potential health benefits.