Improvements in gelatin cold water solubility after electrospinning and associated physicochemical, functional and rheological properties

Abstract

A major limitation of gelatin feedstocks for industrial food and pharmaceutical applications is the lack of solubility at room temperature, necessitating use of drum/dry blending processes, combined with additives. Herein, electrospinning is investigated as an alternative route for producing cold water soluble 100% gelatin feedstock in place of powders. The physicochemical, rheological and functional properties of electrospun gelatin and an industrially available gelatin powder feedstocks were compared. Optimal conditions for producing gelatin nanofiber sheets were found to be 25% (w/v) polymer concentration in a binary solvent system of acetic acid: water (3:1 v/v), a spinning voltage of 25 kV, a flow rate of 0.5 ml/h and a tip-to-collector distance of 150 mm. The production of nanofibers from gelatin powder did not change the nature of the material. The glass transition temperature of gelatin nanofibers was lower than gelatin powder. Conversion of gelatin powder into nanofiber sheets also increased the dissolution rate in water at ambient temperature and promoted emulsion and foam forming ability, as well as increasing foam stability. Loss tangent measurements revealed that the gel formed by the gelatin nanofibers could be characterized as a weak gel. No difference was observed in the Young's modulus of samples made from gelatin nanofibers and powder, and the 0.2% (w/v) gelatin nanofiber sample yielded a higher viscosity than the 0.1% (w/v) concentration. Gelatin nanofibers have promising potential to be used as feedstock in food technology when cold water solubility and improved control of physical, functional and textural properties are required.