The roles of cell wall polymers and intracellular components in the thermal softening of cassava roots

Cassava varieties Iapar 19 – Pioneira (short cooking time, domestic vegetable), Taquari (medium-to-long cooking time, domestic vegetable), and Branca de Santa Catarina (long cooking time, industrial vegetable), were selected in order to investigate the cell wall and compositional basis for these textural differences. Pioneira had lower levels of Ca2+ and Mg2+, and higher levels of phytic acid and monovalent cations than the longer cooking time varieties. Detailed cell wall analysis indicated that the longer cooking Branca cultivar had higher levels of chelator-insoluble pectic polysaccharides. The potential causative roles of these different features were evaluated using vortex-induced cell separation (VICS) studies. Time to achieve the complete VICS of Branca cultivar was reduced to that of Pioneira with externally-supplied chelating agents (CDTA) and Na2CO3. Taquari roots did not respond in this way indicating a different biochemical basis for the maintenance of cell adhesion. The results are discussed in relation to the thermal stability of texture in these cassava varieties.