Physicochemical and antioxidant properties of pectin fractions extracted from lemon ( Citrus Eureka ) peels

Pectin, a natural polysaccharide, holds versatile applications in food and pharmaceuticals. However, there is a need for further exploration into extracting novel functional fractions and characterizing them thoroughly. In this study, a sequential extraction approach was used to obtain three distinct lemon pectin (LP) fractions from lemon peels ( Citrus Eureka ): LP extracted with sodium acetate (LP -SA), LP extracted with ethylenediaminetetraacetic acid (LP-EDTA), and LP extracted with sodium carbonate and sodium borohydride (LPSS). Comprehensive analysis revealed low methyl-esterification in all fractions. LP -SA and LP -SS displayed characteristics of rhamnogalacturonan-I type pectin, while LP-EDTA mainly consisted of homogalacturonan pectin. Notably, LP -SA formed self -aggregated particles with rough surfaces, LP-EDTA showed interlocking linear structures with smooth planes, and LP -SS exhibited branch chain structures with smooth surfaces. Bioactivity analysis indicated that LP -SA had significant apparent viscosity and ABTS radical scavenging activity, while both LP-EDTA and LP -SS showed excellent thermal stability according to thermogravimetric analysis (TGA). Furthermore, LP -SS exhibited remarkable gel -forming ability and significant hydroxyl free radicals scavenging activity. In conclusion, this study presents a novel method for extracting various lemon pectin fractions with unique structural and bioactive properties, contributing insights for advanced applications in the food and pharmaceutical sectors.