title: Thermal analysis of some natural polysaccharide materials by isoconversional method.
abstract: Isoconversional thermal analysis of some important polysaccharides from functional foods is reported. Various thermal parameters including apparent activation energy (Ea), pre-exponential factor (A) were worked out, and the fitness of data to different models describing the degradation kinetics of polysaccharides was studied. The polysaccharides from Mimosa pudica (MP), Plantago ovata (PO), Argyreia speciosa (AS), Acacia nilotica (AN), P. ovata husk (HK) and Acacia modesta (AM) exhibited multistep degradation while those from Astragalus gummifer (AG), Salvia aegyptiaca (SA) and Ocimum basicilicum (OB) degraded mainly in single step. Generally, the degradation was exothermal. The average Ea values as determined by Flynn-Wall-Ozawa method were found to be in the range 132-187 kJ mol(-1). The mean comprehensive index of thermal stability (ITS) fell in the range 0.33-0.43. All the materials under investigation except those from SA and AS appear to be as stable as some of the important commercial materials used as pharmaceutical ingredients. Model-fitting analysis revealed that the major degradation step follows first-order kinetics.
authors.affiliation: Department of Chemistry, Forman Christian College, Lahore 54600, Pakistan. saeediq50@hotmail.com
authors.forename: Mohammad S
authors.initials: MS
authors.lastname: Iqbal
authors.forename: Shazma
authors.initials: S
authors.lastname: Massey
authors.forename: Jamshed
authors.initials: J
authors.lastname: Akbar
authors.forename: Chaudhary M
authors.initials: CM
authors.lastname: Ashraf
authors.forename: Rashid
authors.initials: R
authors.lastname: Masih
mesh_terms: D006358:Hot Temperature; D007700:Kinetics; D010944:Plants / Q000737:chemistry* / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D013818:Thermogravimetry / Q000379:methods*; D014675:Vegetables / Q000737:chemistry* / Q000378:metabolism
chemical_list: D011134:Polysaccharides