Flour and parenchyma cells from sweet potato and potato: a comparative study of their physicochemical properties and digestibility

In tuber crops, starch granules are enveloped in parenchyma cells (PCs) which are bound together by pectin-rich middle lamella. Flour and intact PCs were isolated from sweet potato (Shinyulmi cultivar) and potato (Dejima cultivar). Starch granules and PCs of potato were larger than those of sweet potato. PCs from both species had lower contents of crude ash, crude protein, and crude lipid compared to their flour counterparts. As temperatures rose, the solubility patterns varied between flour and PC of sweet potato, while remaining consistent for potato. Potato PC had higher gelatinization temperatures compared to its flour counterpart, while sweet potato PC had lower temperatures than its flour, possibly due to the considerable loss of non-starch polysaccharide during its PC preparation. Compared to cooking, baked PCs showed a more evident inhibition on digestion. This study suggests that such species differences need to be considered when utilizing PCs in food processing.