Enzymatic extraction of galactan-rich rhamnogalacturonan I from potato cell wall by-product

- Effects of parameters of endo-polygalacturonase-catalyzed isolation of rhamnogalacturonan I (RG I) were investigated.
- Interaction between cell wall concentration and reaction time was the most determinant for the yield.
- Saccharide profile of RG I was dependent on the interaction effect of cell wall and enzyme concentrations.
- High enzyme concentrations resulted in the debranching of neutral side chains (>7% galactan; >15% arabinan) of RG I.
- Validated models can be used to generate RG I targeting specific structures and functional properties.

Potato cell wall was used as low-value source for the enzymatic extraction of galactan-rich rhamnogalacturonan I (RG I). The effects of selected reaction parameters of endo-polygalacturonase from Aspergillus niger-catalyzed isolation of RG I and their interactions were investigated by response surface methodology. Models were developed to relate independent parameters (cell wall concentration, enzyme amount, reaction time) to responses (yield, neutral sugar content, saccharide molar composition, weak acidic fraction proportion). The most significant parameters that affected extracted polysaccharide yield and its galactose (Gal) and arabinose (Ara) contents were the cell wall concentration and enzyme amount. The interaction between the cell wall concentration and the reaction time was the most determinant for the yield. However, the cell wall concentration and the enzyme amount exhibited significant interaction effect on Gal and Ara contents. Comparison of predicted and experimental values validated the established predicted models, which can be used to identify the conditions for the isolation of RG I-type pectic polysaccharides with selected structural and saccharide composition properties. The monosaccharide composition and the linkage patterns confirmed the isolation of galactan-rich RG I type pectic polysaccharides. The present study is expected to increase the capability to generate RG I targeting specific composition and functional properties.