Pectins from food waste: characterization and functional properties of pectic polysaccharide extracted from pumpkin (Cucurbita moschata Duch.) peels

Pumpkin peel is a main by-product produced during pumpkin consumption and processing, which is often disposed of as food waste. Therefore, it is necessary to develop ways to utilize pumpkin peel. In this study, the pectic polysaccharides were extracted from pumpkin peel, and their properties were evaluated. Results indicated that the extraction yield of pectin polysaccharides from Dongsheng pumpkin peel was the highest. Meanwhile, among the pumpkin peel pectic polysaccharides (PPs), Dongsheng PP exhibited the highest methylation degree (22.38%), acetylation degree (15.92%), molecular weight (6.26 × 10⁵ Da) and initial apparent viscosity. Variety had little effect on the microstructure and functional groups of PPs. Compared with the other PP samples, Beibei PP (BBP) had the lowest molecular weight coupled with highest protein content, resulting in the highest emulsifying activity, emulsion stability and antioxidant activity. In addition, all the PPs had the ability to promote the growth of probiotics, and BBP and Banli PP (BLP) shown better capacities to promote the growth of Lactobacillus acidophilus and Bifidobacterium breve. Hence, it could be concluded that extraction pectin from pumpkin peel is a potential method for the utilization of pumpkin peel.