Valorization of sugar beet pulp waste by extraction of pectin via novel technologies and application in food systems

Sugar beet pulp is a waste from sugar industry that can serve as a source for pectin. Application of novel processing methods including microwave and ultrasound as a pretreatment in the extraction of pectin from sugar beet pulp and use of resulting extracts in food systems were investigated. Industrial sugar beet pulp in citric acid solution was exposed to ultrasound, microwave or heat treatment as conventional method. Extracted pectins were characterized and their functionality in an emulsion and a fermented milk beverage was evaluated. Extraction yield and protein content were enhanced by ultrasound treatment from 5.3% to 10.3% and 6.6% to 8.6%, respectively, while galacturonic acid content (56.8–61.3%) and degree of esterification (72.3–75.8%) were similar regardless of the extraction method. FTIR analysis indicated that ultrasound treatment caused structural changes in the pectin. Sugar beet pectins obtained by ultrasound and microwave treatments yielded higher stability, 53.1% and 55.2%, respectively, in o/w emulsion compared to about 40% by conventional method and commercial citrus pectin. All pectin extracts and citrus pectin resulted in about 2-fold increase in the consistency of the milk beverage while serum separation in the beverage was reduced more by citrus pectin. The results demonstrated that sugar beet pectin is a viable food ingredient. Both ultrasound and microwave technologies offer advantages in reduction of time and energy usage in extraction.