Maltose Solutions Research Articles

Prospects for the use of complex additive to improve biotechnological characteristics of yeast Saccharomyces Cerevisiae

One of the main factors affecting the quality of bread are microbiological and biochemical processes occurring in dough semifinished products as a result of yeast activity. These processes can be controlled by regulating the biotechnological characteristics of yeast, which allows to intensify technological operations of baking production. Baking yeast should have high enzymatic activity, the ability to release carbon dioxide in anaerobic conditions and quickly adapt to changes in the composition of the nutrient medium. These properties of yeast can be improved by pre-activation in nutrient media containing components that intensify the synthesis of fermentation enzymes in yeast cells. The aim of the work was to study the effect of pre-activation of pressed baker's yeast Saccharomyces cerevisiae in nutrient media with food complex additive on their biotechnological characteristics: lifting force and enzymatic activity (zymase, maltase). Yeast lifting force was determined by accelerated method. Zymase and maltase activities were determined by measuring the time for which 10 cm3 of carbon dioxide is released during digestion of glucose and maltose solutions by yeast, respectively. The novelty of the work consists in the establishment of parameters of preliminary activation of baker's yeast Saccharomyces serevisiae with the use of food complex additive. It is shown that the optimal duration of yeast pre-activation is 20 min. Pre-activation of pressed yeast contributed to the increase of their biotechnological characteristics: yeast lifting force increased by 46.9 %, zymase activity - by 37.7 %, maltase activity - by 13.4 %. The obtained results indicate the promising application of yeast pre-activation in nutrient medium with food complex additive in the production of bakery products

Isomerization of maltose to maltulose under microwave heating using uncalcined scallop shell powder

Uncalcined scallop shell powder, consisting mainly of calcium carbonate, and an aqueous maltose solution were placed in a pressure-resistant vessel and heated in a domestic microwave oven to isomerize maltose to maltulose. When a maltose solution (50 mL) was heated at a power of 700 W, a high maltulose yield of approximately 30 % was achieved in as short a time as 105 s. As the reaction progressed, the shell powder dissolved and neutralized acidic by-products to suppress the decrease in pH, keeping the pH above 7, where the isomerization by Lobry de Bruyn-Alberda van Ekenstein transformation proceeded. The average selectivity for isomerization of maltose to maltulose under various reaction conditions was 0.822. This would be because the shell powder kept the pH of the reaction solution in the range of 7–9 and suppressed the progression of side reactions. The coloration of the reaction solution increased rapidly when the yield of maltulose approached its maximum value. This indicated that if the reaction were to be stopped when the yield of maltulose was close to its maximum value, a high yield of maltulose solution with low coloration could be obtained.

Polyglycerol polyricinoleate and lecithin stabilized water in oil nanoemulsions for sugaring Beijing roast duck: Preparation, stability mechanisms and color improvement

Traditional Beijing roast duck often suffers from uneven color and high sugar content after roasting. Water-in-oil (W/O) nanoemulsion is a promising alternative to replace high concentration of sugar solution used in sugaring process according to similarity-intermiscibility theory. Herein, 3% of xylose was embedded in the aqueous phase of W/O emulsion to replace 15% maltose solution. W/O emulsions with different ratios of lecithin (LEC) and polyglycerol polyricinoleate (PGPR) were constructed by high-speed homogenization and high-pressure homogenization. Distribution and penetration extent of solutions and emulsions through the duck skin, as well as the color uniformity of Beijing roast duck were analyzed. Emulsions with LEC:PGPR ratios of 1:3 and 2:2 had better stability. Stable interfacial film and spatial structure were important factors influencing emulsion stabilization. The stable W/O emulsions could more uniformly distribute onto the surface of duck skin and longitudinally penetrate through the skin than solutions.

Hydrogenolysis of disaccharides into propylene glycol on copper-containing oxides

The hydrogenolysis of 10 % methanol-water solutions of sucrose and maltose to propylene glycol on supported copper-containing catalysts in flow reactor was studied. The highest concentration of propylene glycol in the reaction products (0.23 mmol/ml) has been obtained in the hydrogenolysis of sucrose on 23Cu-1Cr2O3/Al2O3 catalyst with its full conversion at 170 °C/4.0 MPa H2 and a load on catalyst of 0.8 mmol С12Н22О11/gcat/h. At that, the catalyst productivity towards propylene glycol consists 0.7 mmol/gcat/h. Hydrogenolysis of maltose in these conditions is characterized by 81 % conversion and low (0.04 mmol/ml) concentration of propylene glycol in the reaction products. The main byproducts of sucrose hydrogenolysis are ethylene glycol, hydroxyacetone, 1,2-butanediol, 1,4-butanediol and sorbitol. Concentration of propylene glycol in the reaction products of sucrose hydrogenolysis on 23Cu-1Cr2O3/Al2O3 does not change significantly (0.23-0.18 mmol/ml) during 18 h of catalyst operation. Сomparison of the productivities of 23Cu-1Cr2O3/Al2O3 catalyst to propylene glycol in hydrogenolysis of 10 % solutions of sucrose (0.7 mmol/gcat/h) and glucose (0.9 mmol/gcat/h) suggests that glucose is more suitable for the production of propylene glycol than studied disaccharides.

Determining the Optimal Vacuum Frying Conditions for Silver Herring (Spratelloides gracilis) Using the Response Surface Methodology.

Vacuum frying (VF) is a selective technique for producing high-quality fried food that is mostly used on vegetables, fruits, and potato chips. It is rarely applied to the production of aquatic (especially fish) products. The purpose of this study is to explore whether VF technology can be applied to the preparation of dried silver herring products and to obtain the optimal VF conditions. The response surface methodology (RSM) was used to examine the factors affecting the quality of silver herring (Spratelloides gracilis) products after VF, namely temperature (75, 90, and 105 °C), duration (25, 35, and 45 min), and concentration (0, 15, and 30%) of maltose solution used to immerse the samples during pre-processing. The results indicated that VF temperatures had significant impacts on water activity (Aw), moisture content, yield, oil content, lightness (L* value), and colour difference (ÄE). The higher the VF temperature, the lower the Aw, moisture content, yield, and oil content of the product, but the higher the L* value and ΔE. Next, a longer VF duration resulted in higher oil content of the product. Maltose concentration was significantly and positively correlated with the yield and fracturability of the product. RSM analysis indicated that the optimal combination of processing conditions was a VF temperature of 105 °C, VF duration of 25 min, and maltose concentration of 27%. Under these VF conditions, the silver herring products had a moisture content of 3.91%, Aw of 0.198, oil content of 21.69%, L* value of 28.19, ΔE of 27.31, and fracturability of 359 g/s. In summary, vacuum frying technology is suitable for the preparation of dried silver herring products, and this study can provide the optimal processing conditions for seafood processors to obtain better quality.

Improvement of IMO production and prebiotic properties using optimal substrate and transglucosylation period

This study focused on the determination of a suitable concentration of maltose and maltodextrin in saccharified rice solution for transglucosylation to reduce the IMO production time and maintain prebiotic properties. Maltose and maltodextrin reported as main substrates for transglucosidase enzyme were tested for a promising rate of IMO synthesis. Maltose utilization by transglucosidase enzyme was higher than that found in maltodextrin in the production of isomaltose, isomaltotriose, isomaltotetraose, isopanose, and isomaltohexaose. Hence, the liquefaction and saccharification of rice flour were optimized to produce high maltose solution. The liquefaction of rice flour at 95 °C with KLEISTASE T10S enzyme concentration of 0.035; 0.055 and 0.075%v/w, and rice flour of 20, 25, and 30%w/v were investigated for maximum hydrolysis. The liquefied solution was further treated with Biozyme LC enzyme concentrations (0.05, 0.015, and 0.20%w/v) at 45 or 60 °C. The result of maximum hydrolysis percentage was found as 87%w/w from the liquefying rice flour of 20%w/v for 40 min with 0.075%v/w Transglucosidase L “Amano” enzyme concentration. Subsequent saccharification with 0.2%v/w enzyme concentration at 60 °C for 30 min yielded highest maltose of 149.1 g/L; maltodextrin, 31.4 g/L, and glucose, 5.3 g/L. Tranglucosylation of the high maltose solution was monitored within 24 h at 6 h intervals. The maximum IMO was at 6 h and declined at a longer transglucosylation period. The trends of the prebiotic index and prebiotic activity scores were parallel with IMO concentration. In conclusion, the IMO could be synthesized from a low-cost resource of maltose in approximately 6 h at 65% yield.

Effects of W/O Nanoemulsion on Improving the Color Tone of Beijing Roast Duck.

Traditional Beijing roast duck is often brushed with a high concentration of maltose solution (15% w/v) and shows ununiform color after roasting. A novel W/O nanoemulsion was applied to improve the color tone of Beijing roast ducks and, meanwhile, reduced the amount of sugar. For the W/O emulsion, 3% (w/v) xylose solution as the aqueous phase, soybean oil as the oil phase, and polyglycerol polyricinoleate (PGPR) and whey protein isolate (WPI) as co-emulsifiers were fabricated by high-pressure homogenization. Particle size measurement by Zetasizer and stability analysis by Turbiscan stability analyzer showed that WPI as co-emulsifier and internal aqueous phase at pH 9 decreased the droplet size and improved the emulsion stability. In addition, by color difference evaluation, the W/O nanoemulsion improved the Maillard reaction degree and color tone of Beijing roast duck. The molecular structure and key composition of pigments on the surface of Beijing roast duck skins were also identified and characterized by UV-vis spectroscopy and UHPLC-MS. This study creatively offers theoretical guidance for increasing applications of W/O-nanoemulsion-based Maillard reaction in the roast food industry, especially for the development of reduced-sugar Beijing roast duck with uniform and desired color satisfying consumers' acceptance and marketability.

Unexpected High-Substrate-Dependent Ketonization of Aldose on Niobium Phosphate-Supported Magnesia: An Emphasis on Surface Chemisorption

A water-tolerant magnesia-based solid base was prepared by combining the use of a non-equilibrium and highly structured dual-porous niobium phosphate (NbP) as the support and high-temperature thermal treatment. The crystal growth of MgO changed, and the bond length of Mg–O was longer than that of pure MgO after it was supported on NbP, which led to the higher basic property of O2– on the surface of MgO/NbP to act as a solid base catalyst toward aldose ketonization. It was revealed that the prepared solid base MgO/NbP exhibited high substrate dependence for ketonization of saccharides, facilitating the use of glucose and glucose-containing aldo-disaccharides─including maltose, cellobiose, lactose, and melibiose─due to their lower free energy after chemisorption than that of pentose, and a moderate reverse reaction barrier in aqueous solution. It was demonstrated that ketonization mainly occurred on the solid surface, especially in the case of high substrate concentration, which was different from the conventional opinion. The type of glycosidic bond and the constituent monosaccharides also affected the yield and selectivity of rare keto-disaccharides. The high performance of the MgO/NbP catalyst toward ketonization of disaccharides was realized as the typical yield and the productivity of maltulose reached 14.2% and 42.6 g·kg-solution–1·h–1, respectively, when treated with 30.0 wt % maltose solution at 130 °C. Although deactivation issues, such as leaching of ions and coke deposition, still remain to be solved, the catalyst has potential to be used in synthesizing high-value rare keto-disaccharides.

Concept, design, and measurement methodology of a highly dynamic thin film dryer for experimental in situ drying manipulation.

This paper describes the technical setup and validation of a thin film drying device in which the conditions such as air temperature, relative humidity, and velocity can be controlled in the range of 20-200 °C, 0-1.5ms-1, and vapor mass flows up to 1200gmin-1. For the first time, it is possible to perform in situ manipulation of the drying kinetic in a highly dynamic manner. The setup allows for a precise online determination of drying and rehydration kinetics; the recording of relevant process parameters such as air humidity, air and surface temperature; and the monitoring of optically observable material properties. The concept for rapid real-time changes in drying conditions is explained, and the constructive details are elucidated. Highly precise gravimetry by a proposed measurement methodology and simultaneously avoiding condensation during rapid parameter changes is accomplished. This is achieved by the combination of minimized thermal inertia of the system, air conditioning via carrier gas-free evaporation, and a highly responsive active insulation. The influence on the drying kinetics by temperature, humidity, and air velocity is shown with experiments on aqueous maltose solution, and the experimental precision is validated. The validation showed a high grade of accuracy regarding gravimetric determination with a maximum observed mass difference of 0.21% referring to the dried product. The dynamics of the setup under in situ changes in drying conditions is exemplified by further experiments. In addition, the presented setup for the first time enables the real time manipulation and observation of kinetically coupled processes such as crystallization behavior, morphology formation, or material degradation during drying. Therefore, it has important practical value for the development of efficient and energy-saving drying methods and products with specific, tailor-made properties.

Starch-Coated Magnetic Iron Oxide Nanoparticles for Affinity Purification of Recombinant Proteins.

Starch-coated magnetic iron oxide nanoparticles have been synthesized by a simple, fast, and cost-effective co-precipitation method with cornstarch as a stabilizing agent. The structural and magnetic characteristics of the synthesized material have been studied by transmission electron microscopy, Mössbauer spectroscopy, and vibrating sample magnetometry. The nature of bonds between ferrihydrite nanoparticles and a starch shell has been examined by Fourier transform infrared spectroscopy. The data on the magnetic response of the prepared composite particles have been obtained by magnetic measurements. The determined magnetic characteristics make the synthesized material a good candidate for use in magnetic separation. Starch-coated magnetic iron oxide nanoparticles have been tested as an affinity sorbent for one-step purification of several recombinant proteins (cardiac troponin I, survivin, and melanoma inhibitory activity protein) bearing the maltose-binding protein as an auxiliary fragment. It has been shown that, due to the highly specific binding of this fragment to the starch shell, the target fusion protein is selectively immobilized on magnetic nanoparticles and eluted with the maltose solution. The excellent efficiency of column-free purification, high binding capacity of the sorbent (100–500 µg of a recombinant protein per milligram of starch-coated magnetic iron oxide nanoparticles), and reusability of the obtained material have been demonstrated.

Effect of trisodium citrate dihydrate on thermophysical properties of saccharides in aqueous media at different temperatures: Volumetric and acoustic properties

From the measurements of density, (ρ) and speed of sound, (u), the intermolecular interactions of D-maltose monohydrate and D-lactose monohydrate with trisodium citrate (TSC) have been explored in aqueous medium at temperatures, T = (293.15–313.15) K, pressure p = 0.1 MPa. From the experimental density measurements, apparent molar volume (VΦ), limiting apparent molar volume (VoΦ) and limiting apparent molar volume of transfer (VoΦ,tr) have been determined for various solutions of maltose and lactose in aqueous TSC. In addition, using experimental speed of sound data, apparent molar isentropic compressibility (KΦ,s), limiting apparent molar isentropic compressibility (KoΦ,s) and partial molar isentropic compression of transfer (KoΦ,s,tr) have been calculated.Further, apparent molar expansibility (EoΦ), Hepler's constant values(∂EoΦ∂T)Pand hydration number (nH)have been assessed to contribute the interpretations received from the acoustic and analysis. The assessed outcomes were construed in terms of diverse intermolecular interactions present in the ternary systems (saccharides+ water + TSC) through a co-sphere overlap model. From the Hepler's constant structure breaking nature of the solute have been confirmed.

Broadband Dielectric Spectroscopic Analysis toward Characterization of the Hydration State and Bioprotective Superiority of Trehalose.

Alteration of the hydrogen-bond (H-bond) network by trehalose is acknowledged as a bioprotective agent. However, most studies exploring the hydration superiority of the trehalose structure are limited structure are limited by the computational cost or a narrow-range spectrum. In the present study, the structural and dynamical behaviors of the H-bond network of trehalose and maltose solutions were observed and compared with a broadband dielectric spectrum (100 MHz-18 THz) to investigate the influence of the trehalose structure on the bioprotective function. From the relaxation time, the reorientation cooperativity, resonant frequency, and damping constant of water-water vibration, the symmetric structure of trehalose allowed a more significant H-bond strengthening effect and homogeneous aqueous environment. In contrast, the difference in the hydration number between trehalose and maltose was negligible. Thus, the enhanced H-bond strengthening effect and homogeneous aqueous environment owing to the symmetric structure are the essential factors that contribute to the remarkable bioprotective effect of trehalose.

Transmission of the effect of Mercurius corrosivus 30 CH on -amylase in cell free medium through water.

Abstract
 Background
 Mercurius corrosivus 30CH promoted -amylase activity in a cell free medium invitro. -amylase causes hydrolysis of starch. The activity of the enzyme is measured in terms of the amount of maltose liberated due to breakdown of starch. In a number of experimental studies it has been demonstrated that the effect of homeopathic potency would be transmitted from one plant to another through water. Here one leaf of a pair of plants was dipped in water in a beaker. The two beakers were connected by a water filled polythene tube. The effect of treatment of one plant with homeopathic potency would be observed in the directly treated plant as well as the connected plant. Two groups of toads were kept in water in two different containers. The two containers were connected by a water filled polythene tube. The effect of treatment of one group of toads with homeopathic potency would be observed in both the directly treated group as well as the connected group.
 Objectives
 The purpose of the present study is to see whether the effect of Mercurius corrosivus 30 CH on -amylase in one test tube would be transmitted to another test tube connected with the former by water filled capillary tube.
 Methods
 Mercurius corrosivus 30 CH was diluted with distilled water (1:100). Two hard glass test tubes each containing -amylase were connected with a water filled capillary tube while one test tube received Mercurius corrosivus 30CH solution, the other only the control solution. The control solution consisted of equal amount of 90% ethanol diluted with water (1:100).There were two more test tubes, one containing same amount of distilled water instead of Mercurius corrosivus 30 CH solution and the other test tube the same amount of 90% ethanol (1:100) as in the control set. After 10 mins starch solution in Sodium acetate buffer was added to each test tube. The enzyme in each test tube was allowed to react with starch for 15 mins and then it was stopped by DNSA (Dinitro salicylic acid) solution .The activity of -amylase was measured by standard biochemical process. The breakdown product maltose in each test tube was quantified by a standard curve prepared by measuring the optical density of the maltose solution at 560 nm in a UV-VIS Spectrophotometer. This experiment was repeated 20 times.
 Results
 Activity of -amylase was expressed in terms of the amount of maltose liberated from breakdown of starch with standard errors in 15mins at a fixed temperature. The data were analyzed statistically using t-test. Mercurius corrosivus 30 CH enhanced the enzyme activity significantly in the directly treated test tube as well as the connected one (p

Screening, Cloning, Expression and Characterization of New Alkaline Trehalose Synthase from Pseudomonas monteilii and Its Application for Trehalose Production.

Trehalose is a non-reducing disaccharide in increasing demand for applications in food, nutraceutical, and pharmaceutical industries. Single-step trehalose production by trehalose synthase (TreS) using maltose as a starting material is a promising alternative process for industrial application due to its simplicity and cost advantage. Pseudomonas monteilii TBRC 1196 was identified using the developed screening method as a potent strain for TreS production. The TreS gene from P. monteilii TBRC 1196 was first cloned and expressed in Escherichia coli. Purified recombinant trehalose synthase (PmTreS) had a molecular weight of 76 kDa and showed optimal pH and temperature at 9.0 and 40°C, respectively. The enzyme exhibited >90% residual activity under mesophilic condition under a broad pH range of 7-10 for 6 h. Maximum trehalose yield by PmTreS was 68.1% with low yield of glucose (4%) as a byproduct under optimal conditions, equivalent to productivity of 4.5 g/l/h using enzyme loading of 2 mg/g substrate and high concentration maltose solution (100 g/l) in a lab-scale bioreactor. The enzyme represents a potent biocatalyst for energy-saving trehalose production with potential for inhibiting microbial contamination by alkaline condition.

Effects of Impurities from Sugar Excipient on Filtrate Flux during Ultrafiltration and Diafiltration Process.

Sugar excipients such as sucrose and maltose are widely used for biopharmaceutical formulation to improve protein stability and to ensure isotonicity for administration. However, according to recent literature, pharmaceutical-grade sucrose contained nanoparticulate impurities (NPIs) that result in protein aggregation and degradation. The objective of this study was to evaluate the filtrate flux behavior of sugar solution during ultrafiltration (UF) and diafiltration (DF). Filtrate flux data were obtained using either a tangential flow filtration (TFF) system for DF experiments or a normal flow filtration system for UF experiments. In diafiltration experiments, which were performed using 7 g/L of human immunoglobulin G in a 20 mM histidine buffer with the 100 mM sucrose or maltose, the filtrate flux with sucrose solution decreased significantly. In contrast, the one with maltose solution was in good correspondence with the calculated filtrate flux accounting for the effects of solution viscosity. This large decline in the flux was also observed during UF experiments, in which the presence of NPIs was identified by dynamic light scattering analysis and by capturing an SEM image of the membrane surface after filtration. In addition, highly purified sucrose resulted in a much lower flux decline in TFF in the absence of NPIs. These results provide important insights into the factors governing the optimization of the UF/DF process using appropriate excipients for biopharmaceutical formulation.

The Assembly of the Mixture of Two Ionic Surfactants in Polyols Media at Variable Temperatures: Combined Conductivity and Theoretical Investigations

AbstractHerein, the aggregation phenomena of the two cationic amphiphiles, the hexadecyltrimethylammonium bromide (CTAB), and tetradecyltrimethylammonium bromide (TTAB), has been investigated in the presence of monosaccharide (glucose) and disaccharide (maltose) at varying compositions and temperatures. The critical micelle concentration (cmc), degree of ionization (g), and several thermodynamic properties have been estimated applying the conductivity measurement technique. To explore the consequence of additives on the mixed micellization of TTAB + CTAB, glucose as monosaccharide having two concentrations (1% & 5% (w/w) glucose) and maltose as disaccharide containing single concentration (1% (w/w)) have been employed. Together with the mixture of TTAB and CTAB, investigation of the physicochemical parameters of pure amphiphiles in glucose and maltose solutions was quantified. The efficiency of the additives in depressing the cmc values followed the order: 1 (w/w) % maltose >5 (w/w) % glucose >1% (w/w) glucose. The ideal cmc (cmcid), activity coefficients, and β values suggested the synergistic attraction (attractive force) between these two surfactants. By utilizing the Rubingh model, the evaluated micellar mole fractions of CTAB (α1) coupled with the ideal mole fraction () imply the increase of the contribution of CTAB in the mixed micellization with rising the α1 values. The values of the negative excess free energy () implied the stability of the mixed micelle formed. The changes in standard enthalpy (ΔH°m) and changes in standard entropy (ΔS°m) of micellization reveal the presence of different modes of interactions like electrostatic, ion‐dipole, H‐bonding, and hydrophobic interactions among the studied components.

Film formation and surface renewal on a rotating spoked disk for polymer devolatilization

The film flow and surface renewal of highly viscous liquid on a rotating spoked disk were investigated experimentally and numerically. In practical applications, the liquid is a polycarbonate melt with very high viscosity and Newtonian behavior at low shear rates. In the experiments, a maltose solution was used. The film thickness on the rotating disk was measured by an electrical conductivity probe. The Volume of Fluid (VOF) model combined with the sliding mesh method was used to simulate the film formation process. The simulated dimensionless film thickness and the film formation process agree well with the experimental results. The film flow and surface renewal under different operation conditions were evaluated. Gravity and viscous forces dominate the process with inertia playing a marginal role. A scraper was designed to intensify transfer processes on the film significantly.

The effect of size and solid content in hydrolysis of sweet potato starch using endogenous beta-amylase enzyme

Sweet potato contains significant amount of endogenous amylase enzymes. The endogenous enzymes can be used in maltose production from sweet potatoes to carry out pre-hydrolysis of the starch to some extent, follow by complete hydrolysis using external enzymes. The main objective of the current study is to investigate the effect of particle size and solid to liquid ratio in hydrolysis process of sweet potato starch using endogenous enzymes. The extent of hydrolysis process is measured by dextrose equivalent of the crude maltose solution. Hydrolysis process consists of liquefaction and saccharification process. The liquefaction process is carried out at 71.5°C and pH 6 for 25 minutes while saccharification process is carried out at 53°C and pH 5,5 for 72 hours. Dextrose equivalent is measured using Lane-Eynon method. The results show that the access of enzyme to the potato tubers is the key to hydrolysis process. The smaller size of tubers gives bigger surface area while lower solid-to-liquid ratio increases enzyme mobility but decreases sugar concentration. Base on the results, a simulation shows that the pre-hydrolysis of sweet potatoes using endogenous enzymes can save almost a half of enzymes required for traditional hydrolysis process.

Microwave vacuum evaporation as a potential technology to concentrate sugar solutions: A study based on dielectric spectroscopy

Traditional vacuum evaporation in the sugar industry generally relies on steam and is characterized by low energy efficiency. Microwaves may be an alternative heat source to steam. In this study, three sugar solutions (glucose, maltose, and trehalose) were concentrated by lab-scale microwave vacuum evaporation (MVE). The dielectric spectroscopy in the frequency range of 0.1-6.5 GHz and the temperature range of 5-90 °C was determined and analyzed. Results showed that the dielectric loss factor increased with concentration and decreased with temperature at 2.45 GHz. The maltose solution had a lower microwave absorption and conversion capacity than glucose or trehalose solution. Meanwhile, the hydrogen bond interactions of trehalose solution were stronger, contributing to higher intermolecular interactions. These results may account for the distinct evaporation efficiencies of MVE on the three sugar solutions. Due to the rapid heating rate (up to 2.86 ± 0.08 °C/s) and massive water loss (closer to 2/3 total mass of the feed solution) over a short period of time (10 min at a microwave power density of 40 W/g and a vacuum pressure of 50 kPa), MVE may be a substitute for conventional methods. Furthermore, the dielectric spectroscopy can be an effective tool to help guide MVE to obtain sugars with high quality. • Dielectric spectroscopy of three sugar solutions was determined and analyzed. • Maltose solution had weaker microwave absorption and conversion ability. • Strong intermolecular interactions in trehalose solution impeded evaporation. • Rapid heating and massive water loss occurred during microwave vacuum evaporation. • Microwave vacuum evaporation may be a substitute for conventional evaporation.

Effect of short-term intake of four sweeteners on feed intake, solution consumption and neurotransmitters release on mice.

This study focused on the effect of short-term intake of sweeteners on feed intake, solution consumption and neurotransmitters release on mice. The results showed that the free drinking of 10mM sucralose solution, 100mM maltose solution, 3mM saccharin solution and 3g/L stevioside solution for 32days will not affect the normal development of the body weight and feed intake of the mice. The consumption of maltose solution was significantly higher than that of the other sweeteners. The leptin and insulin levels increased significantly after the short-term intake of these four sweeteners. The dopamine (DA) content in the whole brain of the mice increased significantly only in the maltose group. These results indicate that the short-term intake of the preferred concentrations of maltose, stevioside, sucralose and saccharin will not affect the body weight and feed intake of the mice. Mice prefer maltose solution to other sweeteners solutions. The 100mM maltose solution and 3mM saccharin solution could result in the oxidative stress on mice after 32days' short-term intake. Compared with other sweeteners, only sugars that could be broken down into small molecules of glucose might have a positive effect on dopamine levels.