Enzymatic degradation studies of pectin and cellulose from red beets

The influence of structural features of the cell wall polysaccharides pecti n and cellulose on the enzymatic degradation of red beet was evaluated. Alc ohol-insoluble substances and acetone-insoluble residues were prepared from red beets and characterized with respect to the content of dietary fibre, pectin fractions, neutral saccharide composition and water absorption. The high methylated and high-acetylated pectin component was partly soluble in water and in EDTA. Pectin was hardly extractable from alcohol-insoluble sub stances as well as from red beets. Isolated pectin could not be completely degraded by pectolytic enzymes. After de-acetylation, the pectic acid from red beets was degradable in a similar rate like citrus pectic acid. From al cohol-insoluble substances, several cellulose and lignin. fractions were pr epared and analysed. A cellulose preparation from red beets was intensely d egraded by cellulases with high activities as shown by the release of reduc ing end-groups, viscosity and scanning electron microscopy. Cell wall prepa rations from red beets were able to bind high amounts of water. A decrease in water absorption during enzymatic action or changes in viscosity and flo w behaviour are sensitive markers for decomposition or depolymerization pro cesses. Furthermore, an inhibitor of microbial enzymes was isolated from re d beets and acetone-insoluble residues. The main reason for the poor enzyma tic liquefaction or maceration of red beets by pectolytic and cellulolytic enzymes is the high degree of acetylation of the pectin component.