Acidic-heating induced protein fibrils derived from perilla seed residues: spotlight on assembly behavior, conformational changes and structure-function relationships

In vitro fibrillation of food-derived proteins is increasingly accepted as a promising strategy to prepare new food ingredients, which have broader functional properties than natural protein. In current study, acidic-heating (90 °C, pH 2.0) was performed for perilla seed protein isolate (PSPI) derived from oilseed residues to evaluate the feasibility to produce protein fibrils. TEM images revealed that PSPI were hydrolyzed and reassembled a fundamental linear structure of fibrils after 6 h of heating, as reflected by the variation in particle size distribution. And the branching effects were observed with prolonged time. The conformational changes of PSPI were systematically assessed by electrophoresis, fourier transform infrared spectroscopy, fluorescence spectroscopy, circular dichroism, molecular dynamics simulations. Together with the results of surface hydrophobicity, zeta-potential confirmed that the self-assembly behavior of PSPI based fibrils was dominated by hydrophobic and electrostatic interactions. In addition, correlation analysis was combined to reflect the dynamical variation on emulsification, foaming, viscosity, interfacial and antioxidant properties during the structural evolution of PSPI. Overall, in-depth insights on the potential of perilla residues to convert into protein fibers will provide theoretical support for the regulation of functional properties of plant proteins and expand the potential applications of oilseed residues in the food field.