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Influence of Water on Molecular and Morphological Structure of Various Starches and Starch Derivatives
Author(s) -
Fechner Petra M.,
Wartewig Siegfried,
Kiesow Andreas,
Heilmann Andreas,
Kleinebudde Peter,
Neubert Reinhard H. H.
Publication year - 2005
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.200500410
Subject(s) - starch , amylose , amylopectin , swelling , chemistry , absorption of water , environmental scanning electron microscope , raman spectroscopy , chemical engineering , potato starch , scanning electron microscope , materials science , organic chemistry , composite material , physics , optics , engineering
In this study the influence of water on untreated, pregelatinised, and chemical modified starches was investigated. Because of their different botanical source, the starch products contain various quantities of amylose and amylopectin. The water vapour absorption capacity of the starches was studied by sorption/desorption and thermogravimetrical measurements. Higher absorption capacities were found for potato starch and for starches containing carboxymethyl and hydroxyethyl groups. Characteristic molecular differences found by Raman spectroscopy were evaluated for untreated and modified starches. To this end, the starch raw materials were classified into groups with similar pretreatments and properties based on cluster analysis. Additionally, the gelatinisation of starch‐water mixtures (gels, powders, and films) was continuously studied using temperature‐dependent Raman spectroscopy. In comparison with powder spectra, the Raman spectra of the starch films showed shifts in band positions in the range of the CH deformation and CH stretching modes. With the exceptions of high‐amylose maize starch and carboxymethylated starch, all starches form films. Starch films differ in their surface structures, water contact angles, and rates of water drop absorption, which might be caused by the different retrogradation properties. The swelling and shrinking behaviour of starch films was investigated at the morphological level by in situ environmental scanning electron microscopy (ESEM) experiments and evaluated by grey value analysis. Films of untreated starch show stronger swelling and shrinking than films of pregelatinised products.