Rheology of supersaturated sucrose solutions

Quintas, Mafalda A. C.; Brandão, Teresa R. S.; Silva, Cristina L. M.; Cunha, Rosiane L.

doi:10.1016/j.jfoodeng.2005.08.011

Cited by 80 publications

(80 citation statements)

References 30 publications

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“…Though more pronounced in our data, the temperature dependence of the diffusivity is clearly present in the Stokes-Einstein estimates. In addition, the magnitude of the temperature dependence increases with sucrose concentration in both our measurements and the Stokes-Einstein predictions based on the Quintas et al (2006) parametrization.…”

Section: Stokes-einstein Comparisonsupporting

confidence: 68%

“…Assuming a hydrodynamic radius of r H = 0.4 nm = 4 Å for PEG-4 (Kuga, 1981; for more information, see Sect. 4.3), the viscosity of binary sucrose at a RH of 74 % (Quintas et al, 2006) implies D PEG 5 × 10 −9 cm 2 s −1 . For comparison, the experimental diffusivity of sucrose in sucrose at room temperature and the same RH was shown to be 2.0 × 10 −9 cm 2 s −1 (Price et al, 2016).…”

Section: Activity Coefficientsmentioning

confidence: 98%

“…In comparison to our 19.5 • C measurement, Stokes-Einstein underestimates D PEG by about a factor of ∼ 140-600 over the whole experimental range. The break-down of Stokes-Einstein seems much more pronounced if the measured diffusivities are compared to the temperature dependent Williams-Landel-Ferry (WLF) parametrization by Quintas et al (2006) (∼ 3-4 orders of magnitude). Note that, in contrast to the Song et al (2016) parametrization, we extrapolate far beyond the scope of the experimental data the parametrization is based on (see blue, 10 • C, and red, 20 • C, hollow symbols in Fig.…”

Section: Stokes-einstein Comparisonmentioning

confidence: 99%

“…Thus a strong effect at the PEG-4 levels considered here is not substantiated by experimental data. Figure 8 shows a comparison of the measured PEG-4 diffusivities with diffusivities calculated from literature viscosity data for aqueous sucrose Quintas et al, 2006). To estimate the hydrodynamic radius, data for PEG 200, i.e., a polydisperse mixture of polyethylene glycols with an average molecular weight of 200 g mol −1 comparable to PEG-4 with 194.23 g mol −1 , were considered.…”

Section: Stokes-einstein Comparisonmentioning

confidence: 99%

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Diffusivity measurements of volatile organics in levitated viscous aerosol particles

et al. 2017

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Abstract. Field measurements indicating that atmospheric secondary organic aerosol (SOA) particles can be present in a highly viscous, glassy state have spurred numerous studies addressing low diffusivities of water in glassy aerosols. The focus of these studies is on kinetic limitations of hygroscopic growth and the plasticizing effect of water. In contrast, much less is known about diffusion limitations of organic molecules and oxidants in viscous matrices. These may affect atmospheric chemistry and gas-particle partitioning of complex mixtures with constituents of different volatility. In this study, we quantify the diffusivity of a volatile organic in a viscous matrix. Evaporation of single particles generated from an aqueous solution of sucrose and small amounts of volatile tetraethylene glycol (PEG-4) is investigated in an electrodynamic balance at controlled relative humidity (RH) and temperature. The evaporative loss of PEG-4 as determined by Mie resonance spectroscopy is used in conjunction with a radially resolved diffusion model to retrieve translational diffusion coefficients of PEG-4. Comparison of the experimentally derived diffusivities with viscosity estimates for the ternary system reveals a breakdown of the Stokes-Einstein relationship, which has often been invoked to infer diffusivity from viscosity. The evaporation of PEG-4 shows pronounced RH and temperature dependencies and is severely depressed for RH 30 %, corresponding to diffusivities < 10 −14 cm 2 s −1 at temperatures < 15 • C. The temperature dependence is strong, suggesting a diffusion activation energy of about 300 kJ mol −1 . We conclude that atmospheric volatile organic compounds can be subject to severe diffusion limitations in viscous organic aerosol particles. This may enable an important long-range transport mechanism for organic material, including pollutant molecules such as polycyclic aromatic hydrocarbons (PAHs).

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Section: Stokes-einstein Comparisonsupporting

confidence: 68%

Section: Activity Coefficientsmentioning

confidence: 98%

Section: Stokes-einstein Comparisonmentioning

confidence: 99%

Section: Stokes-einstein Comparisonmentioning

confidence: 99%

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Diffusivity measurements of volatile organics in levitated viscous aerosol particles

et al. 2017

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“…In this case, the increase in the solution concentration caused an increase in the osmotic gradient and, consequently, a faster water loss leading to greater diffusivity values. Moreover, the solution viscosity decreases exponentially with temperature (QUINTAS et al, 2006), which may facilitate mass transfer phenomena. Considering the influence of initial fruit:solution ratio, the almost parallel lines observed in Figure 4 indicates no significant effect of interaction between this variable and the solution concentration on the initial mass rate exchange.…”

Section: Optimization Of the Osmotic Dehydration Processmentioning

confidence: 99%

Effect of process variables on the osmotic dehydration of star-fruit slices

et al. 2012

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The objective of this work was to study the effect of blanching and the influence of temperature, solution concentration, and the initial fruit:solution ratio on the osmotic dehydration of star-fruit slices. For blanching, different concentrations of citric and ascorbic acids were studied. The samples immersed in 0.75% citric acid presented little variation in color in relation to the fresh star-fruit. Osmotic dehydration was carried out in an incubator with orbital shaking, controlled temperature, and constant shaking at 120 rpm. The influence of process variables was studied in trials defined by a complete 23 central composite design. In general, water loss and solids gain were positively influenced by temperature and by solution concentration. Nevertheless, lower temperatures reduced water loss throughout the osmotic dehydration process. An increase in the amount of dehydrating solution (initial fruit:solution ratio) slightly influenced the evaluated responses. The process carried out at 50 ºC with a solution concentration of 50% resulted in a product with lower solids gain and greater water loss. Under these conditions, blanching minimized the effect of the osmotic treatment on star-fruit browning, and therefore the blanched fruits showed little variation in color in relation to the fresh fruit.

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The effect of local dynamics of Atto 390‐labeled lysozyme on fluorescence anisotropy modeling

Babcock

Brancaleon

2015

Biopolymers

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Fluorescence anisotropy decay is a popular optical technique to study the structure, size, shape and even functions of biomolecules. The method measures the time dependence of the depolarization of a fluorophore and is therefore sensitive to the changes in the rotational motion (e.g., aggregation and binding) or changes in the mobility of segments of biopolymers (such as the ones associated with tertiary structure changes). Fluorescence anisotropy decay often requires the use of fluorescent dyes that need to be covalently attached to the biomolecule. The location of the attachment on the biomolecule (e.g., a protein) and the linker used, affect the mobility of the dye and its anisotropy decay. With this study we have combined the experimental data with molecular dynamic simulations to offer a more correct interpretation of the fluorescence anisotropy decay of a popular fluorescent dye (Atto 390) attached to the N-terminus of Hen Egg White Lysozyme (HEWL). Our model shows how the use of relatively simple molecular dynamics computation to simulate the motion of the dye, provide a model to interpret the experimental fluorescence anisotropy decay that yields a better estimate of the hydrodynamic radius of HEWL. The improvement is due to a more detailed description of the segmental motion of the dye attached to the protein.

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Rheology of supersaturated sucrose solutions

Cited by 80 publications

References 30 publications

Diffusivity measurements of volatile organics in levitated viscous aerosol particles

Diffusivity measurements of volatile organics in levitated viscous aerosol particles

Effect of process variables on the osmotic dehydration of star-fruit slices

The effect of local dynamics of Atto 390‐labeled lysozyme on fluorescence anisotropy modeling

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