Utilization of Bitter Orange Seed as a Novel Pectin Source:Compositional and Rheological Characterization

The seeds from bitter orange,the by-product of juice making units,hold the potential to facilitate novel,easy yet high-quality pectin extraction.To test this hypothesis,orange seed pectin(OSP)was extracted by distilled water and its compositional parameters and rheological behavior were then evaluated.Results showed that galacturonic acid was the major component of OSP(∼425 mg/g)confirming the purity of the extracted pectin,followed by glucose and some minor neutral sugars.The Mw(weight-average molar mass),Rn(number average molar mass),and Rz(z-average molar mass)values for the OSP were 4511.8 kDa,61 nm,and 61.1 nm,respectively.Rheological measurements showed a shear-thinning behavior for OSP so that the viscosity of the gum decreased by increasing the temperature from 5 to 45℃.The Power-law model fitted as the best rheological model describing the flow behavior of OSP.The strain sweep dynamic rheological measurements confirmed an entangled network structure for OSP and the NaCl addition to the gum dispersion decreased the consistency coefficient from 35.6 to 23.18 Pa.sn,while the flow behavior index remained unchanged.These results demonstrate that the OSP can be used as a new source of pectin,with likely a wide range of applications in the food industry.

Mechanical and Thermal Properties of Sugar Palm Fiber Reinforced Thermoplastic Polyurethane Composites:Effect of Silane Treatment and Fiber Loading

The aim of the present study was to develop sugar palm fiber(SPF)reinforced thermoplastic polyurethane(TPU)composites and to investigate the effects of fiber surface modification by 2%silane treatment and fiber loading(0,10,20,30,40 and 50 wt%)on the mechanical and thermal properties of the obtained composites.Surface treatment was employed to improve the fiber-matrix interface,which was expected to boost the mechanical strength of the composites,in terms of tensile,flexural and impact properties.Thermal properties were also investigated by thermal gravimetric analysis(TGA)and dynamic mechanical analysis(DMA)to assess the thermal stability of the developed composites.Furthermore,scanning electron microscopy(SEM)was used to study the tensile fracture samples of composites with a view towards evaluating the effects of fiber surface treatments on the fiber/matrix interfacial bonding.The findings of this study reveal that the silane treatment has determined good bonding and linkage of the cellulose fiber to the TPU matrix,hence contributing to enhanced mechanical and thermal properties of the composites.The composite formulation with 40 wt%sugar palm fiber loading showed optimum values such as 17.22 MPa for tensile,13.96 MPa for flexural,and 15.47 kJ/m^2 for impact strength.Moreover,the formulations with higher fiber content exhibited satisfactory values of storage modulus and thermal degradation,while their good interfacial adhesion was evidenced by SEM images.