Large-scale extraction of rhamnogalacturonan I from industrial potato waste

Potato pulp is rich in dietary fibres and is an underutilised material produced in large quantities by the potato starch factories. Potato fibres are especially rich in rhamnogalacturonan I (RG I). RG I is a pectic polysaccharide with a high degree of branching and until now undegraded RG I has only been extracted in small amounts limiting the application possibilities for RG I. The present paper describes a large-scale extraction process providing large quantities of undegraded RG I readily available. The extraction process includes enzymatic starch removal using purified Termamyl, enzymatic RG I solubilisation using a highly purified polygalacturonase, and finally purification using depth filtration and ultrafiltration. The extracted RG I has a high molecular weight and a monosaccharide composition comparable to RG I extracted by analytical extraction procedures. The large amount of RG I available by the presented method allows for thorough structure–function analyses and tailoring of RG I to specific functionalities.