Aqueous Sucrose Solutions Research Articles

Modeling of solute transport inside plant tissue during osmotic dehydration of apple

The accumulation of solutes on the food surface has resulted in notable contradictions between data resulting from modeling and information observed experimentally. Hence, the mechanisms involved in the transport of solutes in the plant tissue during osmotic dehydration (OD) have not been well documented. The purpose of this study was to analyze solute concentration at different depths of osmotically dehydrated apple cylinder with the use of a conventional (sucrose) and a non-conventional (stevia) osmotic agent. Solute concentration was modeled by Fick's law in order to identify the thicknesses within the tissue where the solute is transferred under a diffusive mechanism. Samples were dehydrated in sucrose (30 and 50°Brix) and stevia (3 and 6% w/w) aqueous solutions. Samples were cut in five slices (0.5, 2, 4, 7, 10 mm in z direction) from the surface to the food center. Sample properties such as: water loss, solute gain, moisture content, solute concentration and effective diffusivity coefficients at different tissue depths and time periods of dehydration process were determined. Results showed the concentration of solutes was higher in the surface than the center for both osmotic solutions: stevia and sucrose. Fick model did not allow an adequate description of the experimental data in the area of solutes accumulation, suggesting that transfer of solutes on the tissue surface is governed by other transport mechanism different from diffusion. This result opens new ways for future research of the solutes transport within plant tissue. Under this approach, the surperficial impregnation of solutes at the surface and a diffusive phenomenon inside the sample center could be considered.

Optical Properties of Hyperosmotic Agents for Immersion Clearing of Tissues in Terahertz Spectroscopy

We measured the transmission spectra of the most common hyperosmotic agents, such as pure glycerol, propylene glycol (PG), dimethyl sulfoxide (DMSO), polyethylene glycol (PEG) with molecular weights of 200, 300, 400, and 600 Da, their aqueous solutions, and aqueous solutions of sucrose, glucose, fructose, and dextran 40 and 70. The experiments were carried out using a THz pulsed spectrometer with an evacuated measuring compartment to eliminate the effect of water vapor on spectral measurements. We reconstructed the dielectric characteristics of hyperosmotic agents in the spectral range from 0.1 to 2.5 THz and plotted a dependence of the amplitude absorption coefficient on the concentration of the considered agents at a frequency of 0.5 THz. The results are useful for selecting optimal agents for immersion optical clearing in the THz range.

Heat transfer and power consumption of Newtonian and non-Newtonian liquids in stirred tanks with vertical tube baffles

Agitation and heating of Newtonian and non-Newtonian fluids are commonly used processes in various industrial sectors. Traditionally, heating is mediated using jackets and helical coils. Compared to these conventional techniques, a vertical tube baffles offers geometrical advantages that favor mixture quality and heat-transfer efficiency. However, the available literature on this subject is scarce. Therefore, this study aims to determining expressions for calculating the Nusselt number. To this end, plots of the power number were obtained as functions of the Reynolds number during the agitation and heating of Newtonian and non-Newtonian fluids in batch-operated tanks with vertical tube baffles. Two tanks (10 and 50 L) were used along with pitched blade turbine (PBT) and Rushton turbine (RT) mechanical impellers. The Newtonian (water and aqueous sucrose solutions) and non-Newtonian (carboxymethyl cellulose and Carbopol solutions) fluids were heated at different rotational speeds using the transient technique for heat transfer. The power consumed by the turbine was measured experimentally in terms of the torque generated during motor agitation. Non-linear regression analyses were used to develop models to plot Nusselt as a function of the Reynolds, Prandtl, and the corrective factor of viscosity. The models demonstrated good fit with the experimental results. The power number, a function of Reynolds, was found to vary in the range of 2–5 for the PBT and 5–9 for the RT. The developed heat-transfer models were found to be valid across a wide Reynolds range of 20–200,000 for both impellers in the laminar and turbulent regions, which were delimited at a critical Reynolds of 10,000.

Mutual diffusion coefficient of concentrated trehalose aqueous solutions including supercooled regions measured by the Soret forced Rayleigh scattering method

We measured the binary mutual diffusion (interdiffusion) coefficient of trehalose aqueous solutions D in the concentration range from 0.1 to 0.8 mass fraction and the temperature range from 25 to 50 °C including supercooled regions under atmospheric pressure. The experimental apparatus was based on the Soret forced Rayleigh scattering (SFRS) technique, which uses the Soret effect to create a periodic spatial concentration modulation (Δw <10−5) of micrometer-order fringe spacing in a disaccharide aqueous solution due to the absorption of an optical interference grating generated by two crossing pulsed excitation laser beams (ΔT <10−2 °C). The decay of the mass diffusion process is monitored by the diffraction intensity of a probing laser beam within a few milliseconds. These characteristics of SFRS enabled us to measure highly viscous disaccharide aqueous solutions under supercooled states. The uncertainties of the experimental results were estimated to be within ±3% for low concentration and ±9% for high concentration (w > 0.55). The experimental results demonstrated that the rate of decrease in the mutual diffusion coefficient with the increasing concentration is more pronounced in supercooled regions than in dilute normal regions. We also measured the mutual diffusion coefficient of sucrose aqueous solutions at 30 °C in the supercooled regions to compare the results with those obtained from trehalose. We observed that the mutual diffusion coefficient of the trehalose aqueous solutions were smaller than those of sucrose with the increasing concentration, the ratio of Dtrehalose to Dsucrose showed an almost linear concentration-dependence towards the values that were less than half. Our findings suggest that trehalose can be more effective than sucrose in terms of the relaxation of the composition near their glass transitions.

A review, analysis and extension of water activity data of sugars and model honey solutions

Water activity is a physical property measured in the food industry which helps predict shelf life and microbial activity. Honey normally has a water activity less than 0.6, but this can vary with the amount of crystallization in solution. The aim of this work was to obtain relationships, as fundamental as possible, that can be used to predict the water activity of solutions with compositions similar to honey. Water activity measurements of aqueous sucrose solutions have been well analysed in literature using hydration theory. The analysis based on hydration numbers was easily able to show the quality of data previously published, and hence relationships were proposed for the hydration numbers of glucose, fructose, maltose and glycerol. A model was proposed in this study, to predict the water activity of food systems containing high concentrations of sugars and some electrolytes. The model was analysed and validated using mostly literature data supplemented with new experimental data.

Structural properties and solute transfer relationships during sucrose and stevia osmotic dehydration of apple

The objective of this research was determined the structural changes in plant tissue during osmotic dehydration (OD) of apple in stevia and sucrose aqueous solutions. Macro and microstructural properties at different thicknesses of the sample were determined. For the study of structural properties, samples were cut in five slices at different thicknesses (0.5, 2, 4, 7, 10 mm in z direction) from the surface to the sample center. Anhydrous real density, volume and microscopy images in sample slices were determined and its relationship with the transfer of water and solutes inside the tissue were analyzed. Anhydrous real density in food considering the solids density in the sample was determined. Volume change as a function of moisture migration in the sample was evaluated. Apple samples were immersed into sucrose (30 and 50° Brix) and stevia (3 and 6%) osmotic solutions at 30 °C and 50 °C. The results showed an increase in the anhydrous real density in the area of greater loss of moisture and greater accumulation of solutes within the food. The volume increased in the thicknesses of the center of the sample where the moisture concentration was highest. The greatest alterations of the plant cell structure in the surface of the sample were observed.

Chang approximation for the osmotic pressure of dilute to concentrated solutions

As many regions around the world are facing water scarcity, reverse osmosis (RO) has attracted attention to supply fresh water to such areas. To design and develop energy-efficient RO processes, accurate osmotic pressure values of salt water are critical, yet conventional models of osmotic pressure have significant deviations from the actual values. In addition, absence or high charge of authentic osmotic pressure databases prevents accessing authentic data. Here, we propose combining the Chang correction factor, a polynomial in solution concentration, with traditional osmotic pressure models to approximate the osmotic pressure of dilute to concentrated solutions with high accuracy. The Chang correction factor is determined by regressing a handful of authentic osmotic pressure data divided by theo- retical values calculated using traditional models. Multiplication of resulting polynomials back to corresponding tradi- tional models enables accurate approximation of the authentic osmotic pressure of dilute to concentrated solutions with R2 approaching 1. In addition, generality of the strategy over aqueous and organic solutions is demonstrated by approx- imating osmotic pressure of NaCl and sucrose aqueous solutions and C2H4Cl2-C6H6 and C3H6Br2-C2H4Br2 organic solutions. The approximation strategy proposed and assessed here will be useful to simulate and develop processes for seawater desalination and various industries with high importance.

Cellulose Nanocrystals as a Model Substance for Rigid Rod Particle Suspension Rheology

A cellulose nanocrystal (CNC) sample with an average particle length and width of 170 and 7.8 nm, respectively, that was prepared from chemical pulp via sulfuric acid hydrolysis procedures was used as the test sample for a basic rheological study on rigid rod particle suspensions. The dynamic viscoelastic (VE) behavior of the CNC suspensions dispersed into a highly viscous aqueous sucrose solution at 60 wt % was examined over a range of concentrations (ν) in a semidilute regime at several temperatures. The obtained VE spectra were smoothly superposed onto master curves at a standard temperature of 25 °C using shift factors identical to those of the medium aqueous sucrose solution. The fundamental VE parameters, such as the zero-shear viscosity, the high frequency limiting viscosity, the average relaxation time (τw), and the reciprocal of the steady-state compliance (Je–1), were precisely determined from the master curves as functions of ν. The average rotational diffusion constant of the CNC particles dispersed into suspensions at a dilute condition, Dr0, was also determined at 25 °C using depolarized dynamic light scattering techniques. The relationship τw0 = (6Dr0)−1 was confirmed in the dilute regime, and τw ∝ ν2(6Dr0)−1 was observed in the semidilute regime as predicted by the Doi–Edwards (D–E) theory. Another relationship Je–1 = (3/5)νkBT, where kBT is the product of the Boltzmann constant and the absolute temperature, was also reasonably confirmed in the semidilute regime until the concentration approached the liquid crystal phase transition boundary, as also predicted by the D–E theory. Consequently, the CNC sample behaves as ideal model particles for the detailed study of rigid rod particle suspensions.

Determination of refractive index, size, and solid content of monodisperse polystyrene microsphere suspensions for the characterization of optical phantoms.

Monodisperse polystyrene microspheres are often utilized in optical phantoms since optical properties such as the scattering coefficient and the scattering phase function can be calculated using the Mie theory. However, the calculated values depend on the inherent physical parameters of the microspheres which include the size, refractive index, and solid content. These parameters are often provided only approximately or can be affected by long shelf times. We propose a simple method to obtain the values of these parameters by measuring the collimated transmission of polystyrene microsphere suspensions from which the wavelength-dependent scattering coefficient can be calculated using the Beer-Lambert law. Since a wavelength-dependent scattering coefficient of a single suspension is insufficient to uniquely derive the size, refractive index and solid content by the Mie theory, the crucial and novel step involves suspending the polystyrene microspheres in aqueous sucrose solutions with different sucrose concentrations that modulates the refractive index of the medium and yields several wavelength-dependent scattering coefficients. With the proposed method, we are able to obtain the refractive index within 0.2% in the wavelength range from 500 to 800 nm, the microsphere size to approximately 15 nm and solid content within 2% of their respective reference values.

Оптические свойства гиперосмотических агентов для иммерсионного просветления тканей в терагерцовом диапазоне

The transmission spectra of the most common hyperosmotic agents, such as pure glycerol, propylene glycol (PG), dimethyl sulfoxide (DMSO), polyethylene glycol (PEG) with 200, 300, 400 and 600 Da molecular weights, and their aqueous solutions, as well as aqueous solutions of sucrose, glucose, fructose, dextran 40 and 70 were measured. The experiments were carried out using a THz pulsed spectrometer with a vacuum measuring compartment to reduce the effect of water vapor on spectral measurements. The dielectric properties of hyperosmotic agents were restored in the spectral range from 0.1 to 2.5 THz and the dependence of the amplitude absorption coefficient on the concentration of considered agents at 0.5 THz frequency was constructed. The obtained results make it possible to choose the optimal agents for immersion optical clearing in the THz range.

Planar sucrose substrates for investigating interfaces found in molten chocolate

Abstract We present planar substrates suitable for investigating the sucrose/triglyceride fat interfaces found in molten chocolate with surface science techniques. The planar sucrose substrates are produced by spin coating sucrose onto hydrophilic, silicon oxide-capped, silicon substrates from millimolar aqueous solutions of sucrose. We present the characterisation of the sucrose film thicknesses and crystallinity using X-ray reflectivity and grazing incidence X-ray diffraction, respectively. These sucrose-coated substrates can be used in flow cells for quartz crystal microbalance with dissipation (QCM-D) and neutron/X-ray reflectivity measurements, through which triglyceride oils containing the surfactants commonly used in chocolate manufacture can be flowed. This provides a well-defined, planar, sucrose/triglyceride interface, which can be used to probe the solid/liquid interfaces that are found in molten chocolate at the molecular level.

Densities and Speeds of Sound for Sucrose in Aqueous Solutions of Ammonium Phosphate Salts at Different Temperatures through Density and Speed of Sound Measurements

Volumetric and acoustic studies of sucrose with ammonium phosphate salts, namely, ammonium dihydrogen phosphate (ADP) and diammonium hydrogen phosphate (DAP), have been carried out using an oscilla...

Quantitative estimation of soda ash as an adulterant in aqueous sucrose solution by employing electrical impedance and capacitance spectroscopy

This study analyses measured values of impedance, capacitance and conductance for pure sucrose-DI water solution and when adulterated with different wt% of soda ash (Na2CO3). For pure sucrose-DI water solution, these electrical parameters vary in a quasi-oscillatory nature with increasing sucrose concentration; however, it varies linearly for adulterant wt% ≥ 1%. For pure sucrose-DI water solution, impedance values, in our test setup, are observed to be ranging from 141.53 kΩ to 230 kΩ whereas capacitance and conductance values range from 40.53 pF to 43.91 pF and 4.14 µS to 6.73 µS, respectively, for different sucrose volume fractions. However, under adulterated conditions (upto 5%) such values change from 157.15 kΩ to 107 Ω for impedance, 42.5 pF to 72 µF for capacitance and 6.06 µS to 8.9 mS for conductance, respectively. Coefficient of sensitivity has been extracted which indicates that the system can detect a minimum of 1% Na2CO3 in aqueous sucrose solution.

A-19 Inhibition in Metabolic Syndrome and its Relationship to Orbitofrontal Cortex Activation During Sucrose Evaluation

Abstract Objective Metabolic syndrome(MetS) is associated with disinhibited eating,executive dysfunction,and increased risk of dementia. The orbitofrontal cortex(OFC) has been implicated in literature as an area involved with decision making and reward. Decreased OFC volume has been linked to disinhibited eating and poorer executive functioning skills.However,research examining executive functioning in individuals with MetS fails to address the role of inhibition as it pertains to consumption and risk of developing MetS. We examined the relationship between neuropsychological performance and OFC activation after receiving and rating a sucrose stimulus to determine if OFC activation is associated with executive functioning deficits that may lead to developing MetS. Method Participants were categorized by MetS status(n = 46) and Control(n = 34) with mean age of 49.13±20.29years. During an fMRI session, the Blood-Oxygenation-Level-Dependent(BOLD) response of OFC was recorded while participants rated the pleasantness of an aqueous sucrose solution. Participants were administered the Color-Word Interference Test outside the scanner. Partial Correlation analyses controlling for age examined the relationship between OFC activation during hedonic ratings of sucrose and cognitive performance. Results There was a significant negative relationship between left OFC activity and Color-Word Interference:Inhibition performance for Controls(r(42) = -.365, p = .015) as compared to MetS(r(30) = .141,p &gt; .05). Conclusions Less activity in the OFC during sucrose hedonic rating was associated with better performance on the Inhibition condition for Controls. We speculate that decreased activation in the OFC after sucrose consumption reflects intact executive functioning and perhaps even a preventative factor to developing MetS. Alternatively, it could indicate that Controls are actively inhibiting hedonic responses to sucrose which improves their ability on a test of inhibition.

The role of disaccharides for protein–protein interactions – a SANS study

ABSTRACTThe disaccharide trehalose has shown outstanding anti-aggregation properties for proteins, which are highly important for the possibility to treat neurodegenerative diseases, such as Alzheimer’s and Huntington’s disease. However, the role and mechanism of trehalose for such stabilising effects are still largely unknown, partly because a direct structural picture of how trehalose organises around proteins in an aqueous system is missing. Here we compare small-angle neutron scattering (SANS) data on myoglobin in aqueous solutions of either sucrose or trehalose, in order to investigate their effect on protein–protein interactions. We find that both trehalose and sucrose induces a well-defined protein–protein distance, which could explain why these inhibit protein–protein interactions and associated protein aggregation. It does not however explain the superior anti-aggregation effect of trehalose and suggests that the local solvent structures are highly important for explaining the protein stabilisation mechanism. In a broader perspective, these findings are important for understanding the role of sugars in biological stabilisation, and could provide a structural explanation for why trehalose is a promising candidate for the treatment of neurodegenerative and other protein aggregation related diseases.

Ascorbic acid and calcium uptake in pineapple tissue through different sucrose concentrations of impregnation solution

Incorporation of ascorbic acid and calcium in pineapple slices through impregnation processes in isotonic (∼14 °Bx) and hypertonic (50 °Bx) aqueous solution of sucrose was studied. Changes in water content, soluble solids, pH, mechanical and structural properties, ascorbic acid and calcium content in fruit in function of dipping time and impregnation syrup concentration were evaluated. Isotonic treatment was more effective than hypertonic treatment for the calcium and ascorbic acid incorporation in the plant tissue. Under same conditions, the ascorbic acid uptake was greater than calcium uptake. The fruit firmness was reduced during isotonic treatment and increased by osmotic dehydration, without significant effect of the nutrients addition to the impregnation solution. Additionally, changes in some physicochemical properties of impregnation solution in function of the time have been studied. Nutrient content in impregnation solutions did not register significant changes, which would allow its reuse with some conditioning of the soluble solids concentration.

Monitoring of the freezing stage in a freeze-drying process using IR thermography

This paper presents a new Process Analytical Technology based on the use of an infrared camera and a mathematical model to estimate the ice crystal size distribution obtained at the end of the freezing stage of a vial freeze-drying process. Both empirical laws and first-principle based equations, already presented in the Literature, may be used to this purpose, if the temperature gradient in the frozen product and the freezing front rate are obtained from the analysis of the thermal images. The resistance of the dried product to vapor flux may be then calculated from the distribution of the ice crystal diameters, thus enabling the use of a one-dimensional model for process simulation and optimization. Freeze-drying of 5% and 10% w/w aqueous sucrose solutions, and of 5% w/w aqueous mannitol solutions, were considered as case study. The results were validated comparing the calculated diameters of the pores of the dried cake, corresponding to the ice crystal diameters, with the results experimentally obtained from the analysis of the SEM images, and comparing the values of drying duration and maximum product temperature calculated with the mathematical model with those measured experimentally. Results evidences the effectiveness of the proposed system for process monitoring.

Hydrogen production from sucrose via aqueous-phase reforming

Commercial sucrose was used to produce hydrogen in a combined approach of hydrogenation and aqueous phase reforming (APR). First a mixture of technical sorbitol/mannitol was produced by hydrogenating an aqueous solution of sucrose in a trickle bed reactor over 5 wt % Ru/C. The produced polyols were treated in a continuous reactor at 498 K and elevated pressure deploying a 2.5 wt % Pt/C catalyst to yield hydrogen. The highest hydrogen selectivity was 62%. No large differences were found when comparing a commercial available sorbitol to the technical sorbitol/mannitol mixture in terms of conversion levels and selectivity to the gas-phase products. This was accompanied by a similar distribution of products retained in the liquid phase. The efficiency of APR when utilizing Pt/C was found to be still insufficient for industrial implementation in terms of hydrogen production. Thus, additional efforts should be made to increase the obtained amounts of hydrogen per mole of converted sugar alcohols.

The effects of osmotic dehydration of white cabbage on polyphenols and mineral content

Within this work, the content of polyphenolic compounds, vitamin C and minerals in white cabbage (Brassica oleracea) was studied, as affected by the variety of cabbage (var. Futoški, hybrid Bravo) and osmotic dehydration in different osmotic solutions. Three osmotic solutions were used: 1) aqueous solution of NaCl and sucrose (S1); 2) mixture of S1 and sugar beet molasses in proportion 1:1 (S2); and 3) 100% beet molasses (S3). The osmotic dehydration of cabbage in molasses (S3) resulted in a substantial increase in the content of iron and potassium in the dehydrated cabbage by 80–100%. On the other hand, a loss of minerals (Fe, Mg and Ca) at 30–60% after cabbage dehydration in sucrose solution is presented. Also polyphenols content was significantly increased during osmotic dehydration in molasses particularly for kaempherol (6.63 mg/kg dm), p-cumaric acid (1.01 mg/kg dm), caffeic acid (20.35 mg/kg dm), catechin (153.81 mg/kg dm) and gallic acid (17.54 mg/kg dm). Additionally, osmotic dehydration process demonstrated a good retention of l-ascorbic acid in cabbage.

Shotgun Metagenomics of a Water Kefir Fermentation Ecosystem Reveals a Novel Oenococcus Species.

Water kefir is a fruity, sour, slightly alcoholic and carbonated beverage, which is made by fermentation of an aqueous sucrose solution in the presence of dried figs and water kefir grains. These polysaccharide grains contain lactic acid bacteria (LAB), yeasts, and sometimes bifidobacteria and/or acetic acid bacteria, which consume sucrose to produce exopolysaccharides, lactic acid, acetic acid, ethanol, and carbon dioxide. Shotgun metagenomic sequencing was used to examine the microbial species diversity present at two time points during water kefir fermentation in detail, both in the water kefir liquor and on the water kefir grains, hence representing four samples. Lactobacillus harbinensis, Lactobacillus hilgardii, Lactobacillus nagelii, Lactobacillus paracasei, and a Lactobacillus species similar to Lactobacillus hordei/mali were present in the water kefir examined, along with Bifidobacterium aquikefiri and two yeast species, namely Saccharomyces cerevisiae and Dekkera bruxellensis. In addition, evidence for a novel Oenococcus species related to Oenococcus oeni and Oenococcus kitaharae was found. Its genome was derived from the metagenome and made available under the name of Candidatus Oenococcus aquikefiri. Through functional analysis of the four metagenomic data sets, it was possible to link the production of lactic acid, acetic acid, ethanol, and carbon dioxide to subgroups of the microbial species found. In particular, the production of mannitol from fructose was linked to L. hilgardii, Candidatus O. aquikefiri, and B. aquikefiri, whereas glycerol production was associated with S. cerevisiae. Also, there were indications of cross-feeding, for instance in the case of amino acid supply. Few bacterial species could synthesize a limited number of cofactors, making them reliant on the figs or S. cerevisiae. The LAB species in turn were found to be capable of contributing to water kefir grain growth, as dextransucrase-encoding genes were attributed to L. hilgardii, L. hordei/mali, and Candidatus O. aquikefiri.