The glass transition of amylopectin measured by DSC, DMTA and NMR

Kalichevsky, Monica T.; Jaroszkiewicz, E.; Ablett, S.; Blanshard, J. M. V.; Lillford, Peter J.

doi:10.1016/0144-8617(92)90129-e

Cited by 363 publications

(173 citation statements)

References 11 publications

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“…Both curves closely matched one another, the EPR data being slightly lower than the differential scanning calorimetry data. The T g measured by differential scanning calorimetry has been found to occur above the T g measured at a molecular level (Kalichevsky et al, 1992). The midpoint of T g from EPR measurements was situated slightly above the midpoint of the T g measured by differential scanning calorimetry (data not shown).…”

Section: Molecular Motion and Intracellular Glassesmentioning

confidence: 95%

Influence of Water Content and Temperature on Molecular Mobility and Intracellular Glasses in Seeds and Pollen

Buitink

Claessens

Hemminga³

et al. 1998

Plant Physiology

132

152

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Although the occurrence of intracellular glasses in seeds and pollen has been established, physical properties such as rotational correlation times and viscosity have not been studied extensively. Using electron paramagnetic resonance spectroscopy, we examined changes in the molecular mobility of the hydrophilic nitroxide spin probe 3-carboxy-proxyl during melting of intracellular glasses in axes of pea (Pisum sativum L.) seeds and cattail (Typha latifolia L.) pollen. The rotational correlation time of the spin probe in intracellular glasses of both organisms was approximately 10 ؊3 s. Using the distance between the outer extrema of the electron paramagnetic resonance spectrum (2A zz ) as a measure of molecular mobility, we found a sharp increase in mobility at a definite temperature during heating. This temperature increased with decreasing water content of the samples. Differential scanning calorimetry data on these samples indicated that this sharp increase corresponded to melting of the glassy matrix. Molecular mobility was found to be inversely correlated with storage stability. With decreasing water content, the molecular mobility reached a minimum, and increased again at very low water content. Minimum mobility and maximum storage stability occurred at a similar water content. This correlation suggests that storage stability might be at least partially controlled by molecular mobility. At low temperatures, when storage longevity cannot be determined on a realistic time scale, 2A zz measurements can provide an estimate of the optimum storage conditions.

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Section: Molecular Motion and Intracellular Glassesmentioning

confidence: 95%

Influence of Water Content and Temperature on Molecular Mobility and Intracellular Glasses in Seeds and Pollen

Buitink

Claessens

Hemminga³

et al. 1998

Plant Physiology

132

152

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“…A region related to polysaccharides and carbohydrates at " 75 and 104 p.p.m. (Kalichevsky et al, 1992) and B. subtilis cell walls (Forrest et al, 1991) displayed mobility changes when native spores and preparations with 10 % water were compared. This could indicate increasing hydration of the cortex.…”

Section: Discussionmentioning

confidence: 99%

Effects of hydration on molecular mobility in phase-bright Bacillus subtilis spores

Leuschner

Lillford

2000

Microbiology

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The molecular mobility of 31 P and 13 C in dormant Bacillus subtilis spore samples with different water concentrations was investigated by high-resolution solidstate NMR. Lowest molecular mobility was observed in freeze-dried preparations. Rehydration to a 10 % weight increase resulted in increases in molecular motions and addition of excess water furthered this effect. A spore slurry which had been freeze-dried displayed after addition of excess water similar NMR spectra to native wet preparations. Dipicolinic acid (DPA), which is mainly located in the core, was detected at all hydration levels in 13 C crosspolarization magic angle spinning (CPMAS) but not in single-pulse magic angle spinning (SPMAS) spectra, indicating that hydration had no effect on its mobility. The molecular mobility of 31 P, present mainly in core-specific components, was strongly dependent on hydration. This result suggests reversible water migration between inner spore compartments and the environment, whereas 13 C spectra of DPA indicate that it is immobilized in a water-insoluble network in the core. Scanning transmission electron microscopy revealed that freeze-dried spores were significantly longer and narrower than fully hydrated spores and had a 3 % smaller volume.

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“…This third hydration region (region c) was not observed at -6O"C, perhaps because the wc in this region (c) is close to where freezing and melting transitions become detectable. The viscosity of food polymers at comparable wc values is much lower than that of the glassy state, but it is considerably higher than that of liquid water (Slade and Levine, 1991;Kalichevsky et al, 1992;Angell et al, 1994). This condition is commonly referred to as a "rubbery state" (Slade and Levine, 1991;Peleg, 1993).…”

Section: Cp At Low Wc Valuesmentioning

confidence: 99%

Calorimetric Properties of Dehydrating Pollen (Analysis of a Desiccation-Tolerant and an Intolerant Species)

et al. 1996

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l h e physical state of water in the desiccation-tolerant pollen of Typha latifolia L. and the desiccation-sensitive pollen of Zea mays L.was studied using differential scanning calorimetry in an attempt to further unravel the complex mechanisms of desiccation tolerance. Melting transitions of water were not observed at water content (wc) values less than 0.21 (T. latifolia) and 0.26 (2. mays) g H,O/g dry weight. At moisture levels at which melting transitions were not observable, water properties could be characterized by changes in heat capacity. Three hydration regions could be distinguished with the defining wc values changing as a function of temperature. Shifts i n baseline power resembling second-order transitions were observed i n both species and were interpreted as glass-to-liquid transitions, the glass-transition temperatures being dependent on wc. lrrespective of the extent of desiccation tolerance, both pollens exhibited similar state diagrams. l h e viability of maize pollen at room temperature decreased gradually with the removal of the unfrozen water fraction. I n maize, viability was completely lost before grains were sufficiently dried to enter into a glassy state. Apparently, the glassy state per se cannot provide desiccation tolerance. From the existing data, we conclude that, although no major differences in the physical behavior of water could be distinguished between desiccation-tolerant and h t o l e r a n t pollens, the physiological response to the loss of water varies between the two pollen types.

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The glass transition of amylopectin measured by DSC, DMTA and NMR

Cited by 363 publications

References 11 publications

Influence of Water Content and Temperature on Molecular Mobility and Intracellular Glasses in Seeds and Pollen

Influence of Water Content and Temperature on Molecular Mobility and Intracellular Glasses in Seeds and Pollen

Effects of hydration on molecular mobility in phase-bright Bacillus subtilis spores

Calorimetric Properties of Dehydrating Pollen (Analysis of a Desiccation-Tolerant and an Intolerant Species)

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