Surface Composition and Morphology of Starch, Amylose, and Amylopectin Films
- 12 November 2002
- journal article
- research article
- Published by American Chemical Society (ACS) in Biomacromolecules
- Vol. 4 (1), 166-172
- https://doi.org/10.1021/bm0256810
Abstract
The surfaces of solution-cast films of starch, amylose, and amylopectin were examined with scanning electron microscopy (SEM), atomic force microscopy (AFM), electron spectroscopy for chemical analysis (ESCA), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The surface topography visualized by SEM showed that amylopectin films were very smooth whereas amylose and starch films were rougher. It appears that crystallinity or phase separation in the bulk of the film affects the surface topography. AFM showed that the outmost surfaces of all films were covered with small protrusions, 15−35 nm wide and 1−4 nm high. Studies with ESCA revealed the presence of 3−8% nitrogen on the surfaces. ToF-SIMS indicated that the nitrogen originates from protein because ionic fragments from amino acids and the peptide backbone were found. Extracts from the top surface layer of the starch film showed protein bands in gel electrophoresis (SDS-PAGE) around 60 kDa, which is in the same molecular weight range as the biosynthesizing enzyme GBSS I present in starch granules. The proteins apparently phase separated during film formation and migrated to the surface, resulting in an extensive enrichment of proteins in the film surface, where about 8% of the protein is present in the top 0.01% of the film. We believe that the protrusions observed with AFM could be one or a few proteins aggregated side by side.Keywords
This publication has 18 references indexed in Scilit:
- Networks from α,ω-Dihydroxypoly(dimethylsiloxane) and (Tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxysilane: Surface Microstructures and Surface CharacterizationMacromolecules, 1999
- AFM in studies of thermoplastic starches during ageingCarbohydrate Polymers, 1998
- Structure, mechanical and barrier properties of amylose and amylopectin filmsCarbohydrate Polymers, 1998
- The Surface Chemistry of Starch Granules Studied by Time-of-Flight Secondary Ion Mass SpectrometryJournal of Cereal Science, 1997
- Thermodynamic incompatibility of proteins and polysaccharides in solutionsFood Hydrocolloids, 1997
- Microscopy of starch: evidence of a new level of granule organizationCarbohydrate Polymers, 1997
- Distribution of Nitrogen in the Cationized Potato Starch GranuleStarch ‐ Stärke, 1995
- Development of Starch Based Plastics ‐ A Reexamination of Selected Polymer Systems in Historical PerspectiveStarch ‐ Stärke, 1993
- Microstructure of amylose gelsCarbohydrate Polymers, 1992
- Evaluation of the ESCA technique as a screening method for the estimation of protein content and quality in seed mealsJournal of the Science of Food and Agriculture, 1976