Integrated Processing of Sugar Beet Pulp: Pectin and Microcrystalline Cellulose Production and Their Properties

Sugar beet pulp is a multi-ton waste product of the sugar beet industry. In this study, using chemical processing, beet pectin and microcrystalline cellulose were sequentially obtained from sugar beet pulp by acid extraction and alkali treatment, bleaching, and sulfuric acid hydrolysis, respectively. The resulting biopolymers were characterized using infrared spectroscopy (IR spectroscopy), X-ray diffraction (XRD), atomic force microscopy (AFM), and thermogravimetric analysis (TGA) to determine their chemical structure, morphology, thermal stability, and the crystallinity of the microcrystalline cellulose. Physicochemical analysis showed that the isolated pectin is characterized by a high molecular weight (39.25 kDa) and degree of esterification (75.0%). The crystallinity index of the obtained cellulose, calculated using XRD, is 86.4%. The yield of pectin on the absolute dry weight (ADW) basis was 14.5% by mass, and the yield of microcrystalline cellulose on the ADW basis was 34.5% by mass. Using the TGA/DSC method, it was determined that the thermal degradation temperature of pectin is 257.4°C, and that of microcrystalline cellulose is 344.4°C. The valuable biocompatible biopolymers obtained are in demand in the food and pharmaceutical industries, as well as in medicine and cosmetology.