Production and characterization of mechanically-enzymatically treated suspensions of the food by-product pea hull.

Given the potential health benefits of dietary fiber, incorporating high-fiber by-products such as pea hulls into food products is both sustainable and desirable. However, incorporation into semi-solid or low viscous food products can be challenging due to limited fiber functionality, which is partly attributable to its low solubility. Here, a combined mechanical-enzymatic treatment of pea hulls was performed with the aim of obtaining low viscous, physically stable, oligosaccharide-rich fiber suspensions. The pea hull consisted mainly of cellulose next to (glucurono)xylans, pectic polysaccharides, especially linear arabinans and unesterified homogalacturonans, and xyloglucans. Mechanical-enzymatic treatment of pea hulls was performed using microfluidization (1,750 bar, 3 or 5 runs), and commercial arabinanase and cellulase (50 °C, 30 min) were used for the enzymatic treatment. The chemical-structural and the technofunctional properties of the treated pea hulls were determined. Both mechanically-enzymatically treated pea hulls showed comparable fiber contents (73%-75%) as well as polysaccharide composition and structures. Both treatments resulted in a reduction in particle size, though with different particle size distributions, and improved functional properties of pea hull suspensions. High mechanical intensity was crucial for physical stability of the suspensions and enzymes for partial degradation of polysaccharides. Contrary to our expectations, this was not accompanied by extensive solubilization of insoluble cell wall polysaccharides, which is likely due to the high proportion of crystalline cellulose. Nevertheless, the treated pea hulls showed an improved hydration capacity, and limited amounts of potentially prebiotic di- and oligosaccharides were also released. Overall, the treatments resulted in high-fiber ingredients with small particle sizes (D