Compositional, structural, thermal, and microstructural modifications in black soldier fly larvae (Hermetia illucens)...

This study aimed to determine how alkaline pulsed electric field-assisted extraction modulates the compositional, molecular, colloidal, thermal, and microstructural properties of black soldier fly larvae (BSFL) proteins. Defatted BSFL powder was extracted under alkaline conditions and subjected to pulsed electric field treatments at electric field strengths of 1.25-3 kV/cm and 50-250 pulses. Protein fractions were characterised for composition, structure, colloidal behaviour, thermal properties, and microstructure using amino acid analysis, circular dichroism, Fourier-transform infrared spectroscopy, X-ray diffraction, zeta potential, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and particle size analysis. Crude protein content remained relatively stable, from 56.86 to 57.92 g/100 g. In contrast, pulsed electric-field treatment induced clear intensity-dependent changes in protein composition and structure. Thermal transitions shifted markedly, with onset temperatures ranging from 51.62 to 75.59 °C and enthalpy increasing from 0.65 to 1.17 J/g. Zeta potential remained negative, while circular dichroism, Fourier-transform infrared spectroscopy, and X-ray diffraction confirmed molecular reorganisation. Microstructural and particle-size changes further demonstrated the treatment effects. Alkaline pulsed electric field-assisted extraction can therefore generate black soldier fly larvae protein ingredients with distinct structural, colloidal, and thermal characteristics.