Carbohydrate composition of groundnuts (Arachis hypogea)

The proximate composition of defatted edible groundnut flour, processed and unprocessed, has been determined. The flour contains about 38% total carbohydrates of which oligosaccharides account for 18%, starch 12.5%, hemicelluloses A and B 0.5 and 3.5% respectively and fibre (cellulose) 4.5%. Sucrose 13.90 and 14.55%, raffinose 0.89 and 0.92%, stachyose 1.56 and 1.60%, and verbascose 0.41 and 0.42% represent the oligosaccharide fractions (from 70% alcoholic extract) of unprocessed and processed flour, respectively. In addition the unprocessed flour also contained glucose 0.80% and fructose 0.41 % along with two unidentified spots 0.70%. Hemicellulose A consisted of glucose, arabinose, and xylose (4:0.5:0.1) whereas hemicellulose B had galacturonic acid, glucose, galactose, arabinose and xylose (1:4:1:12:6). The fibre fraction on hydrolysis yielded predominantly glucose with only traces of galacturonic acid and rhamnose. The presence of verbascose and xylose in groundnuts has not been previously reported

Groundnut carbohydrates - a review

This review summarises comparative studies conducted here and elsewhere on the various carbohydrate fractions of groundnut. Mono- and oligosaccharides, starch, xylan, glucomannan and cellulose were some of the fractions isolated and characterised. The xylan was shown to be highly branched, having a backbone of β-1,4-linked D-xylopyranose residues and further substituted at C-2 (9.6%) and C-2, C-3 (15.6%). The glucomannan, containing more of glucose than mannose (mol ratio, 4:1) was a linear β-1,4-linked polymer. Investigations using scanning electron microscope of enzymically digested groundnut starch revealed several types of 'pitting' on the starch granular surface. The effects of processing and germination on the make up of groundnut carbohydrates were also investigated. Incubation of the defatted groundnut flour (GNF) with a partially purified hemicellulase preparation indicated almost complete breakdown of the pentosan constituents and resulted in a greater extraction (over 90%) of proteins from GNF

Structural investigations on two hemicellulosic polysaccharides from groundnut (Arachis hypogea) seed endosperm

A highly branched xylan and a linear, β-d-(1→4)-linked glucomannan are the two hemicellulosic components isolated from the endosperms of groundnut (Arachis hypogea). Electrophoretic, sedimentation, and sugar analysis indicate the polysaccharides to be fairly homogeneous. The O-methyl derivatives of the polysaccharides were analysed, after reduction and O-acetylation, by gas-liquid chromatography and g.l.c.-mass spectrometry. 2,3,4-Tri-O-methyl-d-xylose (3.6 mol), 2,3-di-O-methyl-d-xylose (21.0 mol), 3-O-methyl-d-xylose (2.8 mol), and d-xylose (4.2 mol) were detected in the xylan, whereas 2,3,4,6-tetra-O-methyl-d-glucose and/or mannose (1.6 mol), 2,3,6-tri-O-methyl-d-mannose (5.6 mol), and 2,3,6-tri O-methyl-d-glucose (21.2 mol) were found in the glucomannan. Periodate and Smith-degradation studies substantiate the results of methylation analysis on the xylan. A glucose: mannose ratio of 3:1 for the glucomannan, however, suggests that this fraction may be an aggregate of true glucomannan and glucan or degraded cellulose