Post-extrusion physical properties, techno-functionality and microbiota-modulating potential of hempseed (Cannabis sativa L.) hull fiber

Abstract

One-third of hempseed is composed of fiber, yet this major nutrient is far understudied than the seed's oil, protein, polyphenol or cannabinoid fractions. Here we provided a comprehensive and novel study covering the monosaccharide-linkage composition, physical, functional and microbiota-shifting properties of the fiber-rich (>77%) hempseed hull, which is a major industrial processing by-product. Xylose and cellulose-derived 4-linked glucopyranosyl linkage residue dominated the monosaccharide profile and 1D/2D NMR molecular assignments of hempseed hull. Processing with extrusion technology altered the particle size distribution, FTIR structural characteristics, X-ray diffraction crystallinity and thermal stability of hempseed fiber. Extruded hempseed fiber showed significantly greater soluble fiber content, water and oil binding capacity, dynamic modulus and flow viscosity values in oil and oil-water dispersions, delayed starch gelatinization and inhibited its retrogradation. Integration of 16S rRNA gene sequencing and the rapidly emerging metaproteomics revealed a higher population of Megasphaera elsdenii and Lactobacillus spp., along with their expressed ferredoxin and enolases respectively, in porcine faecal samples after fermentation with hempseed hull fiber. Higher production of propionic, butyric and valeric acid from the microbiota was further observed in fiber-treated faecal inoculum. Finally, the possible microbiota modulating-effect of fiber-bounded unique phenylpropionamides ( N - trans -caffeoyltyramine and lignanamides) from hempseed hull was assessed for the first time. • The effects of extrusion on the fiber profile of hempseed hull were investigated. • Linkage and NMR analysis revealed the molecular composition of hempseed fiber. • Functionality of hempseed fiber was tested in oil, water and starch matrices. • Hempseed fiber may alter gut microbial populations and their expressed proteins. • Microbiota and phenolic amides interaction were explored.