Abstract Sugar beet pulp (Beta vulgaris) is one of the main by-product of the sugar refining industry and contains large amounts of cellulose, hemicellulose, pectin and saccharides. Considering the economic aspects, using sugar beet pulp as a rich source for pectin extraction, separation of cellulose nanofibers, dietary fibers preparation, and biofuels production has been expanded. The aim of this study was the managing of agricultural wastes in order to produce dietary fiber. To increase the quality of sugar beet fibers, chemical treatment using alkaline hydrogen peroxide was performed in order to remove or reduce the intensity of the gray color, unpleasant taste and smell. Also, the electrohydrodynamic method was used as a new non-thermal technology for fiber extraction. The effect of chemical treatment by alkaline hydrogen peroxide and physical treatments such as blanching and electrohydrodynamic on soluble and insoluble fiber contents, physicochemical properties (color, structure and water holding capacity) and thermal properties of sugar beet pulp were eva‎luated. The sugar beet pomace was obtained from sugar factory and was heat treated for 10 and 20 minutes at 90°c and then dried. The dried samples were chemically treated with 3% (weight/volume) alkaline hydrogen peroxide with a ratio of sample to solution of 1:10 for different times (20, 70 and 120 minutes). At the same time as bleaching and chemical treatment, electrohydrodynamic treatment (60 and 120 minutes) was also applied to the samples. Then the samples were neutralized by hydrochloric acid and the residues were washed by distilled water and dried at ambient temperature. The dried fibers were grinded by a planetary ball mill and analyzed. The optimal treatment was eva‎luated based on the maximum water holding capacity and the highest color brightness and the chemical, morphological, thermal and structural characteristics of the optimal sample. The results showed that the amount of soluble fiber in the optimal sample increased by 1.5 % and the amount of insoluble fiber was decreased by 16 %. The color brightness of the optimal sample was increased significantly. The results of the thermal test of the treated samples showed a sharp decrease by the degradation temperature in the treated samples and the optimal sample compared to the control sample. Gel permeation chromatography showed that the molecular weight of the treated fibers was decreased compared to the control sample and the lowest molecular weight was the optimal sample. In order to investigate the functional groups present in the treated fibers, the Fourier transform infrared spectrometer was used, the results showed that the effect of physical and chemical treatment on the functional groups. In addition, in the electron microscopic images, was damaged and breakage in the structure of the treated fibers and a decrease in the size of the fibers were observed. Keywords: sugar beet fibers, electrohydrodynamic, physicochemical properties, structural properties, alkaline hydrogen peroxide

علي نصيرپور , جواد كرامت

ناصر همدمي

هاجر شكرچي زاده , احمد ميره اي