The effect of molecular size on molecular mobility in amorphous oligosaccharides

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The physical properties and especially the molecular mobility of amorphous carbohydrate matrixes directly influence the stability of foods, feeds, and pharmaceuticals and the dessication tolerance of animals and plants during anhydrobiosis. Phosphorescence of the sodium salt of erythrosin B was used to investigate the local molecular mobility in pure amorphous solids of a homologous series of malto-oligosaccharides (maltose, G 2; maltotriose, G 3; maltotetraose, G 4; maltopentaose, G 5; maltohexaose, G 6; and maltoheptaose, G 7); sucrose and maltodextrin DE18 (a hydrolytic fraction of starch) were investigated for comparison. Measurements of the temperature-dependence of the phosphorescence emission energy, an indicator of the extent of local dipolar relaxation, and the phosphorescence emission lifetime, an indicator of the rate of collisional quenching of the excited state by matrix molecules, demonstrate that the local matrix molecular mobility increases with molecular size, and thus, with an increase in T g, in these glucose oligosaccharides. Master curves of the spectroscopic measures of matrix mobility for each oligosaccharide, plotted against T-T g, were not superimposable, suggesting that local properties of the amorphous sugar matrixes, rather than T g per se, influence local matrix mobility. Indicators of spectral heterogeneity also varied with molecular size, indicating that dynamic site heterogeneity also increased with molecular size and thus, T g. These results emphasize the importance of additional research in developing appropriate "molecular rules" for designing amorphous matrix systems with better long-term stability for foods, feeds, or pharmaceuticals.

Original languageEnglish (US)
Pages (from-to)82-93
Number of pages12
JournalFood Biophysics
Volume5
Issue number2
DOIs
StatePublished - Mar 10 2010

Fingerprint

phosphorescence
Oligosaccharides
oligosaccharides
Phosphorescence
Erythrosine
erythrosine
Drug products
maltotriose
Food
drugs
Desiccation
Maltose
maltodextrins
maltose
Pharmaceutical Preparations
Starch
Sucrose
physical properties
Sugar (sucrose)
Carbohydrates

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Food Science
  • Biophysics
  • Bioengineering
  • Applied Microbiology and Biotechnology

Keywords

  • Amorphous solids
  • Dynamic heterogeneity
  • Glass transition
  • Molecular mobility
  • Phosphorescence

Cite this

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abstract = "The physical properties and especially the molecular mobility of amorphous carbohydrate matrixes directly influence the stability of foods, feeds, and pharmaceuticals and the dessication tolerance of animals and plants during anhydrobiosis. Phosphorescence of the sodium salt of erythrosin B was used to investigate the local molecular mobility in pure amorphous solids of a homologous series of malto-oligosaccharides (maltose, G 2; maltotriose, G 3; maltotetraose, G 4; maltopentaose, G 5; maltohexaose, G 6; and maltoheptaose, G 7); sucrose and maltodextrin DE18 (a hydrolytic fraction of starch) were investigated for comparison. Measurements of the temperature-dependence of the phosphorescence emission energy, an indicator of the extent of local dipolar relaxation, and the phosphorescence emission lifetime, an indicator of the rate of collisional quenching of the excited state by matrix molecules, demonstrate that the local matrix molecular mobility increases with molecular size, and thus, with an increase in T g, in these glucose oligosaccharides. Master curves of the spectroscopic measures of matrix mobility for each oligosaccharide, plotted against T-T g, were not superimposable, suggesting that local properties of the amorphous sugar matrixes, rather than T g per se, influence local matrix mobility. Indicators of spectral heterogeneity also varied with molecular size, indicating that dynamic site heterogeneity also increased with molecular size and thus, T g. These results emphasize the importance of additional research in developing appropriate {"}molecular rules{"} for designing amorphous matrix systems with better long-term stability for foods, feeds, or pharmaceuticals.",
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The effect of molecular size on molecular mobility in amorphous oligosaccharides. / You, Yumin; Ludescher, Richard.

In: Food Biophysics, Vol. 5, No. 2, 10.03.2010, p. 82-93.

Research output: Contribution to journalArticle

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AU - You, Yumin

AU - Ludescher, Richard

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N2 - The physical properties and especially the molecular mobility of amorphous carbohydrate matrixes directly influence the stability of foods, feeds, and pharmaceuticals and the dessication tolerance of animals and plants during anhydrobiosis. Phosphorescence of the sodium salt of erythrosin B was used to investigate the local molecular mobility in pure amorphous solids of a homologous series of malto-oligosaccharides (maltose, G 2; maltotriose, G 3; maltotetraose, G 4; maltopentaose, G 5; maltohexaose, G 6; and maltoheptaose, G 7); sucrose and maltodextrin DE18 (a hydrolytic fraction of starch) were investigated for comparison. Measurements of the temperature-dependence of the phosphorescence emission energy, an indicator of the extent of local dipolar relaxation, and the phosphorescence emission lifetime, an indicator of the rate of collisional quenching of the excited state by matrix molecules, demonstrate that the local matrix molecular mobility increases with molecular size, and thus, with an increase in T g, in these glucose oligosaccharides. Master curves of the spectroscopic measures of matrix mobility for each oligosaccharide, plotted against T-T g, were not superimposable, suggesting that local properties of the amorphous sugar matrixes, rather than T g per se, influence local matrix mobility. Indicators of spectral heterogeneity also varied with molecular size, indicating that dynamic site heterogeneity also increased with molecular size and thus, T g. These results emphasize the importance of additional research in developing appropriate "molecular rules" for designing amorphous matrix systems with better long-term stability for foods, feeds, or pharmaceuticals.

AB - The physical properties and especially the molecular mobility of amorphous carbohydrate matrixes directly influence the stability of foods, feeds, and pharmaceuticals and the dessication tolerance of animals and plants during anhydrobiosis. Phosphorescence of the sodium salt of erythrosin B was used to investigate the local molecular mobility in pure amorphous solids of a homologous series of malto-oligosaccharides (maltose, G 2; maltotriose, G 3; maltotetraose, G 4; maltopentaose, G 5; maltohexaose, G 6; and maltoheptaose, G 7); sucrose and maltodextrin DE18 (a hydrolytic fraction of starch) were investigated for comparison. Measurements of the temperature-dependence of the phosphorescence emission energy, an indicator of the extent of local dipolar relaxation, and the phosphorescence emission lifetime, an indicator of the rate of collisional quenching of the excited state by matrix molecules, demonstrate that the local matrix molecular mobility increases with molecular size, and thus, with an increase in T g, in these glucose oligosaccharides. Master curves of the spectroscopic measures of matrix mobility for each oligosaccharide, plotted against T-T g, were not superimposable, suggesting that local properties of the amorphous sugar matrixes, rather than T g per se, influence local matrix mobility. Indicators of spectral heterogeneity also varied with molecular size, indicating that dynamic site heterogeneity also increased with molecular size and thus, T g. These results emphasize the importance of additional research in developing appropriate "molecular rules" for designing amorphous matrix systems with better long-term stability for foods, feeds, or pharmaceuticals.

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