The invention provides a method of producing a hydrolysed pectic polysaccharide isolate that is enriched in rhamnogalacturonan-l, said method comprising the steps of: • providing a pectin-rich substrate that has been obtained from plant material without the use of organic solvent, said pectin-rich substrate containing at least 3% by weight of dry matter of pectic polysaccharides； · subjecting the pectin-rich substrate to enzymatic treatment to partially hydrolyse the pectic polysaccharides, said treatment enzymatic treatment comprising the use of one or more pectinases selected from pectin lyase (EC4.2.2.10), pectate lyase (EC 4.2.2.2), rhamnogalacturonan galacturonohydrolase (EC 3.2.1.173), endo-polygalacturonase (EC 3.2.1.15), exopolygalacturonase (EC 3.2.1.67 and EC 3.2.1.82)； · subjecting the partially hydrolysed pectic polysaccharides to ultrafiltration using an ultrafiltration membrane having a molecular weight cut-off in the range of 5 to 100 kDa； and • recovering the ultrafiltration retentate. The present invention further relates to the hydrolysed pectic polysaccharide isolate obtained by the present method and to a process of preparing a product selected from a nutritional formulation, a food product, a dietary supplement, a beverage or a pharmaceutical product, said process comprising addition of the aforementioned hydrolysed pectic polysaccharide isolate.
