Shomer, I., Department of Food Science, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel
Levy, D., Department of Vegetable Crops, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel

Potato tuber bulkiness was studied in an attempt to elucidate the role of the cell wall (CW) in the tissue texture. The volume of the tissue homogenate was measured before and after enzymatic degradation of insoluble pectic substances (PS) and cellulose. Enzymatic removal of PS resulted in disappearance of the middle lamella ultrastructure, leading to a slight volumetric reduction at most, and both were retained the inner CW and the starch grains in the lumen. Enzymatic degradation of cellulose resulted in the loss of the CW ultrastructure and of the homogenate bulkiness; starch and protoplasmic residues precipitated separately. Among the neutral sugars, starch-glucose was the predominant one (ca. 15% of the fresh weight), and the others were cellulose-glucose, rhamnose, arabinose, xylose, mannose and galactose. The microfibrillar lattice of the cellulose glucan provided the tissue bulkiness and texture. Other factors such as pectin and starch may affect texture through interactions with the microfibrillar lattice of cellulose. © 1988 Kluwer Academic Publishers.