[Dietary fiber and pectin fractions of Beta vulgaris var. conditiva].

The alcohol-insoluble substance (AIS) from red beet (Beta vulgaris var. conditiva Alef.) (3.31% of the edible substance) was extracted sequentially with water, ammonium oxalate, 0.05 N HCl and 0.05 N NaOH. Accordingly 3.93 g, about 0.8 g, 2.96 g resp. 3.80 g galacturonan/100 g AIS were extracted with this procedure. These pectin extracts were purified as Cu2 +-salts and fractionated into a water-soluble and a water-insoluble part. The composition of neutral monosaccharide units was estimated in the fractions. Gal, Ara and Glc dominated; Xyl, Rha and Man were also present but in smaller amounts. A higher GalA content was found in the soluble fractions (with the exception of the alkali extract). Pectins from red beet are middle- or low-esterified and partially acetylated. The composition of the AIS and of the residue after pectin extraction (RE) was determined (14.6 resp. 9.5% pectin; 10,6 resp. 17.6% protein; 58.7 resp. 64.9% total polysaccharides). In the AIS 23.3% soluble and 54.7% insoluble dietary fiber were estimated, whereas in RE 15.3 resp. 54.7% were found (enzymatic method). Following dietary fiber fractions were determined by the detergent method for both preparations: 39.0 resp. 52.7% NDF; 6.3 resp. 4.5% NDF filtrate; 23.6 resp. 41.8% ADF; 1.2 resp. 1.8% lignin. The water binding capacity decreased from 19.85 g water (AIS) to 11. 53 g water (RE) related to 1 g AUS. From these just 50% were found in the NDF fractions and about 13% in the ADF fractions. Alterations of the grown biological structures during pectin extraction and dietary fiber analysis (detergent method) were investigated by scanning electron microscopy.