Chemical and microscopic characterization of potato (Solanum tuberosum L) cell walls during cooking

Cell wall material (CWM) was isolated from noncooked, 5 min cooked, and 15 min cooked potato tissue and accompanying cooking media from the cultivars Irene and Nicola. A mass balance of the material in the different fractions obtained during isolation was made. Chemical compositions of the CWM and cell size distributions of the potato tissues were analyzed. The mealy cooking cv. Irene had more CWM per unit cell surface area than the nonmealy cooking cv. Nicola. These results confirmed observations of the potato cell walls made by transmission electron microscopy. The molar composition of the CWM was comparable for bath cultivars. During cooking, for both cultivars relatively more unbranched than branched pectic polysaccharides were solubilized. However, the type of pectin solubilized after 15 min of cooking was different for the two cultivars. This pectin was relatively more branched, more methylated, and more acetylated for cv. Irene than for cv. Nicola.