Hydrolysed Gelatin-Derived, Solvent-Free, Electrospun Nanofibres for Edible Applications: Physical, Chemical and Thermal Behaviour

Abstract

Electrospinning is a novel technique which has been used recently in the food field. Electrospun nanofibres (NF) have often been produced from non-edible compounds. Biopolymer solutions were developed from gelatin hydrolysed by bromelain in slightly acid medium (pH 4.5). The effects of gelatin concentration, bromelain activity and tip-collector distance on NF morphology and diameter (Df) were studied. Defect-free NF were produced (no beads or droplets), having a 109.5 to 229.3 nm Df. A Box-Behnken design was optimised for studying acetic acid’s effect on gelatin NF thermal behaviour and residual solvent concentration. Gelatin ionisation by acetic acid improved the solutions’ electrospinnability. NF denaturing temperature (Td) was 98.4 °C and gelatin powder Td 102.3 °C. These values were associated with smaller amorphous structure in NF than in gelatin powder. Total acetic acid became evaporated during electrospinning; solvent-free NF were thus produced in line with international food regulations.