Impact of controlled and limited enzymatic hydrolysis on the functionality of hemp protein

In line with the rapidly growing market for plant proteins, hemp seed protein is gaining traction. However, the poor functionality (namely low solubility) of hemp protein limits its use in food applications. An innovative protein modification approach is needed to overcome this challenge. We hypothesize that limited enzymatic hydrolysis using select proteases will improve the solubility of hemp protein.

Objective:
The objective of this study was to evaluate the impact of controlled and limited protein hydrolysis, using two enzymes (trypsin and Protease M) on the structure and functionality of hemp protein concentrate.

Methods:
Hemp protein concentrate (defatted flour) was subjected to enzymatic hydrolysis, using either trypsin, Protease M, or a combination of both, following the pH-stat approach. Preliminary trials were carried out to determine hydrolysis parameters to produce a Protease M (PHHPC) and a trypsin hydrolysate (THHPC) with DH < 14% at both bench and pilot scale. The size distribution and protein/peptide profile were characterized by SDS-PAGE and size-exclusion chromatography. Functional properties evaluated were solubility, gel strength, and emulsion capacity.

Results:
Protein profiling validated the successful hydrolysis of hemp protein components. Trypsin targeted vicilin and the acidic subunit of edestin, while Protease M partially hydrolyzed vicilin and the acidic and basic subunits of edestin. Solubility was significantly improved upon hydrolysis. A significant 6-fold increase in solubility (up to 60% compared to 10%) was observed for PHHPC with a DH of 12% compared to the control. Furthermore, significant increase (almost two-fold) in emulsification capacity of THHPC samples compared to the control.

Research significance to the AOCS membership:
Findings addressed a critical gap in hemp protein utilization by demonstrating scalable enzymatic hydrolysis that result in a significant enhancement in functionality. The remarkable six-fold increase in solubility achieved through controlled enzymatic hydrolysis paved the way for integrating hemp protein into high-protein beverages.