Transformation of hempseed (Cannabis sativa L.) oil cake proteome, structure and functionality after extrusion

The entire protein fractions from hempseed, its oil cake (30-40% protein) and the extruded protein isolate (>90% protein) were investigated. The first semi-quantitative mass spectrometry-based proteomics on hempseed was performed, leading to a sum of 1879 differentially abundant proteins being identified from individual pairwise comparisons of each extruded group compared to unextruded hempseed cake. The 'free-form' amino acid content and total amino acid content of hempseed oil cake were enhanced by up to 315% and 18%, respectively, after extrusion. Changes in the structure and thermal properties of hempseed protein were confirmed through circular dichroism, Fourier transform infrared spectroscopy, scanning electron microscopy and differential scanning calorimetry. The proteomic and structural transformation in the extruded hempseed protein fractions contributed to greater values in majority of tested functionality parameters, such as protein solubility, water and oil binding capacity, emulsification properties, and in vitro digestibility, as compared to their unextruded counterparts.