Exploring hemp protein hydrolysates: functional and nutritional interactions with corn starch
This research characterized the functional and nutritional properties of hemp protein hydrolysates (HPH), prepared from hemp seed by-products using two types of commercial proteases, with a focus on starch digestibility when HPH was added to starch (starch-HPH mixtures) as a food ingredient. Hemp protein was efficiently hydrolyzed by bacterial protease (HPHB, 0.5% Bacillus licheniformis), achieving the target 5% degree of hydrolysis at a lower concentration (0.5%) and shorter time (1 min) compared to pepsin (HPHP, 2% pepsin protease). This study compared these two hydrolysates in terms of their functional properties (water- and oil-holding, emulsifying, and foaming capacities) and examined their surface hydrophobicity, free thiol, total thiol and disulphides contents. Both hemp protein isolate and HPH contained a high proportion of essential amino acids. The 20% starch-HPHP mixtures had significantly enhanced antioxidant activities, particularly in normal corn starch with the ferric reducing potential property and waxy/high amylose corn starch with the radical scavenging (ABTS) property. When the in-vitro starch digestibility of the starch-HPH mixtures was assessed, the 20% high amylose corn starch (HACS)-HPHP mixtures reduced rapidly digestible starch (RDS) by 18.8% compared with the HACS containing no HPHP, while the 10% waxy corn starch (WCS)-HPHB mixtures increased resistant starch (RS) by 10% relative to the WCS containing no HPHB. Overall, this study provides comparative evidence that enzyme-specific hydrolysis can alter the functional characteristics of hemp protein hydrolysates and their behavior in starch-based mixtures.