Heat-induced gelation of protein from mealworm (Tenebrio molitor): influence of pH and zinc concentration

Abstract

Mealworm protein has the general potential to substitute environmentally less favourable, animal derived raw-materials as a gelling biomaterial for zinc enriched wound healing ointments. However, various factors affecting heat-induced gelation of mealworm protein have not yet been studied in detail. Therefore, we investigated the influence of pH (pH 5.5 and 7.5) and zinc concentration (0 M, 0.1 M and 0.3 M) on rheological properties and gel structure of heat-induced mealworm protein gels. Additionally, we used gel solubility experiments and rheological investigations to study the gels with regard to the involved types of interactions. Generally, all examined samples were able to form heat-induced gels. From gel solubility experiments and temperature sweeps, hydrophobic interactions and hydrogen bonds were found to be dominant in all samples. From higher storage moduli we derive the contribution of additional electrostatic and/or covalent interactions in samples with ZnSO4, while shorter linear viscoelastic regimes and more pronounced intracycle strain stiffening were related to less homogenous and more particulate gel structures. From our results strategies for the customisation of gel properties and gel composition may be deduced, that may advance the potential for future utilisation of mealworm protein in wound dressings.

Keywords

• Rheology
• Gel solubility
• Wound healing
• Zinc
• Divalent cations
• Insects