Studies on vegetables. Investigation of water, oxalate, and sodium hydroxide soluble celery (Apium graveolens)polysaccharides: pectic polysaccharides

Pectin fractions were isolated from celery, by extraction with water and aqueous ammonium oxalate. The former fraction had [alpha]25D + 219 degrees and contained L-arabinose, D-galactose, D-glucose, and L-rhamnose in the molar proportion 0.67:1.00:0.12:0.27 and 65.1% galacturonic acid residues having a degree of esterification of 18.4%. The major oxalate soluble pectinic acid (A2:[alpha]25D + 207 degrees; arabinose, galactose, glucose, rhamnose, xylose ratio, 0.69:1.00:0.10:0.67:0.08; galacturonic acid, 70.2%; degree of esterification, 1.65%) was quite similar to the water fraction, with a small difference in the uronic acid content and degree of esterification of the uronate residues and L-rhamnose content but wide variations in specific optical rotation and uronic acid contents compared to pectinic acids A1 and A2. All four pectinic acids were homogeneous on the ultracentrifuge. The pectinic acid A0 from the water fraction was reduced and subjected to methylation analysis, and its general structural features are discussed. Evidence is also presented for the presence of an amyloid and a 4-O-methyl-glucuronoxylan in the sodium hydroxide soluble fraction of celery.