Fractionation and characterisation of pectin-rich extracts from garlic biomass

•Garlic polysaccharides were predominantly pectins.•Pectins extracted from skin biomass were mainly homogalacturonan.•Pectins from leaf biomass comprised both HG and RG-I. Polysaccharides from garlic waste leaf and skin biomass have been isolated using a sequential extraction protocol and characterised using constituent sugar composition and linkage analysis, spectroscopy, chromatography and dilute solution viscometry. The results revealed that the isolated polysaccharides were predominantly pectins. The predominant monosaccharide in all samples was galacturonic acid (>61 %), followed by galactose and rhamnose. The pectins extracted from skin biomass were mainly homogalacturonan (83–91 %), whereas those extracted from leaf biomass comprised both homogalacturonan (62–65 %) and rhamnogalacturonan-I (35–38 %). The degree of methyl esterification of uronic acids in all samples was 44–56 %. The peak molecular weight of the main polysaccharide population in each sample was ∼ 350 x103 g/mol, with leaf extracts and the skin acidic extract containing a second, lower molecular weight peak. Overall, waste garlic biomass is a potential resource for commercial pectin extraction for use in food or pharmaceutical industries.