Rheological and Bioactive Profile of Gelatin—Hemp Protein Hydrogels

TL;DR

This study shows that adding hemp protein to gelatin hydrogels improves their structure, strength, and antioxidant properties, making hemp an active and beneficial component.

Contribution

The study reveals that hemp protein acts as an active structure-forming and functional component in gelatin hydrogels, not just a passive filler.

Findings

Hemp protein increased water-holding capacity and gel strength in gelatin hydrogels.

At higher concentrations, hemp protein influenced the viscoelastic response and mechanical stability of the hydrogels.

Antioxidant activity and color parameters were significantly enhanced with hemp protein addition.

Abstract

The aim of this study was to investigate the effect of hemp protein addition on the structural, rheological, textural, color, and bioactive properties of gelatin hydrogels. Composite systems containing 0–20% hemp protein were analyzed to clarify the mechanism of interaction with the gelatin matrix and to determine whether hemp protein acts as a passive filler or an active structure-forming component. In all formulations, the gelatin concentration was kept constant at 5% (w/w), while hemp protein was added at increasing levels without replacing the gelatin phase, resulting in systems with increasing total solid content. The addition of hemp protein significantly enhanced water-holding capacity and gel strength, as confirmed by rheological measurements and texture profile analysis. Thermorheological analysis revealed a gradual transition from a classic thermoreversible gelatin gel to reinforced composite networks, with the viscoelastic response increasingly governed by the hemp protein structure at higher concentrations (15–20%). Frequency- and amplitude-sweep tests demonstrated improved mechanical stability and reduced frequency dependence. FTIR analysis indicated reorganization of hydrogen bonding and an increasing contribution of hydrophobic interactions related to the lipid fraction of hemp protein. Furthermore, the addition of hemp protein led to a marked increase in antioxidant activity (ABTS and FRAP) and significant changes in color parameters. These results demonstrate that hemp protein functions as an active structural and functional component in gelatin hydrogels, enabling the development of materials with tailored mechanical properties and enhanced bioactivity.

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