Soybean hull insoluble polysaccharides: improvements of its physicochemical properties through high pressure homogenization

COLLETTI, A.C.; DELGADO, J.F.; CABEZAS, D.M.; WAGNER, J.R.; PORFIRI, M.C.

FOOD BIOPHYSICS

SPRINGER

Lugar: Berlin; Año: 2019

1557-1858

Soybean hull is an agroindustrial waste which has not been fully studied as afood ingredient. The aims of this work were to obtain insoluble fibers fromsoybean hull and to evaluate the effect of high pressure homogenization(HPH) on its physicochemical properties. Hull insoluble polysaccharides(HIPS) were obtained in a single step, as the insoluble residue after pectinremoval. FTIR showed bands corresponding to cellulose and hemicellulose inHIPS, and thermogravimetric analysis showed two degradation events at236.3 °C and 325.6 °C, corresponding to cellulose and hemicellulose,respectively. HIPS dispersions (pH 3.00) were subjected to HPH by threecycles at increasing pressures (up to 1000 bar), obtaining soybean hullnanofibers. SEM images show that HPH at 1000 bar reduced the dimensionsof the fiber bundle from 30 to 90 μm in length and 9?15 μm in diameter tonanofibers of 10?30 μm in length and 100?400 nm in diameter. AFM furtherconfirms a heterogeneous distribution of sizes in HIPS and HIPS ,evidencing the presence of individual nanofibers with diameters around 50 ±10 nm and 40 ± 10 nm, respectively, with several μm in length. Furthermore,an increase in water holding capacity from 2.1 to 61 g /g andviscosity from 0.39 to 34,945 Pa.s were achieved as HPH at 1000 bartreatment was applied. HPH increased the interfacial area and promoted theinterconnection of fibers in a hydrated gel-like structure. This explains flowbehavior, which was extensively studied in this work: three-region viscosityprofile (shear-thinning, plateau or shear-thickening and shear-thinning) and apronounced hysteresis loop. Oscillatory rheology was used to study theviscoelastic behavior of HIPS dispersions. HIPS are a source of nanofibers,easy to obtain through a single step of chemical treatment followed by theapplication of high pressures. It is remarkable that the use of few chemicalsolvents is favorable from an environmental point of view. This work alsosuggests a potential application of HIPS to improve physicochemical andstructural properties in acidic foods.