Emulsifying and structural properties of pectin enzymatically extracted from pumpkin

- Enzymatic extraction method was used to produce pumpkin pectin.
- The backbone of pumpkin pectin was mainly composed of α-1,4-d-galacturonic acid.
- Some l-rhamnose was involved in the backbone through α-1,2-linkages.
- Emulsifying properties resulted from presence of protein in the pectin structure.

The present study investigated the emulsifying and structural properties of pectin enzymatically extracted from pumpkin. Pumpkin pectin fraction A was obtained from raw pumpkin with an enzymatic preparation of cellulase and α-amylase. Pumpkin pectin fraction B was achieved by treating the fraction A solution with pronase to reduce protein content. According to the findings (on protein content, galacturonic acid content, neutral sugar composition, and molecular weight distribution), the pronase treatment could remove protein from the fraction A without considerably influencing any other chemical and molecular properties. Moreover, the fraction A exhibited emulsifying properties in water and oil mixture, whereas the removal of protein in the fraction B resulted in the loss of emulsifying properties. The FT-IR and 1D NMR analysis revealed that the backbone of pumpkin pectin is mainly composed of α-1,4-d-galacturonic acid in which a considerable portion of galacturonic acid residues is present as methyl esters, and some l-rhamnose are involved in the linear region of the backbone through α-1,2-linkages.