Free sugars and non-starch polysaccharides–phenolic acid complexes from bran, spent grain and sorghum seeds

• Published in: Journal of cereal science 2019-05, Vol.87, p.124-131
• Main Authors: Miafo, Ange-Patrice Takoudjou, Koubala, Benoît Bargui, Kansci, Germain, Muralikrishna, Gudipati
• Format: Article
• Language: English
• Subjects: Free sugars; Non-starch polysaccharides; Phenolic acids; Sorghum bran and spent grain
• ISSN: 0733-5210; 1095-9963
• DOI: 10.1016/j.jcs.2019.02.002

Free sugars and non-starch polysaccharide-phenolic acid complexes were isolated from sorghum seeds and their major by-products namely bran and spent grain. Total sugar (12.56%) and reducing sugar (10.47%) in free sugars were highest in spent grain. The major soluble sugars identified in materials were maltose, glucose, sucrose, fructose, and raffinose. Hemicelluloses B (2.95–10.82%) and calcium hydroxide extractable polysaccharides (CHEP) (2.20–5.22%) were obtained with the highest yields. The CHEP fractions were completely water-soluble. The major sugars identified in non-starch polysaccharides (NSP) fractions were arabinose, xylose, galactose, and glucose. The Pentose/Hexose ratio was highest in CHEP, in spent grain, it was fourteen-fold that of bran. Ferulic, coumaric and p-hydroxybenzoic acids were present in all the NSP and absent in the alkali-insoluble residues, ferulic acid (56.31–100.73 mg/100 g sample) being the major phenolic acid present. Ferulic, coumaric and vanillic acids were identified as the major phenolic acids in CHEP fractions. Based on their solubility, pentose and phenolic acid contents, NSP from sorghum by-products especially CHEP could exhibit high functional properties when added to foods. •Sorghum grain by-products are important sources of non-starch polysaccharides.•The calcium hydroxide extractable polysaccharides (CHEP) are completely soluble.•The CHEP fractions contained highest amount of total bound phenolic acids.•Ferulic acid is the major phenolic acid bound to all the isolated polysaccharides.•The CHEP could exhibit high functional properties when added to foods.