Gordon-Taylor Model Research Articles

State diagrams of green peas (Pisum sativum L.) powders with different maltodextrin additions.

The purpose of this study was to examine the effect of maltodextrin addition on the physical stability of powdered green peas. The evaluation of the physical state of the material was based on the equilibrium water content of the monolayer (Xm) and the glass transition temperatures of the powders at room temperature (Tg) and in the frozen state (Tg'). Graphical sorption characteristic at 25°C was determined using static-gravimetric method while capacity of the monolayer values was calculated from the mathematical GAB model. Differential scanning calorimetry was carried out in order to determine glass transition lines and freezing curves which combine together were used to plot state diagrams. Relationship between Tg and solid content were shown by using Gordon-Taylor model. Freezing data were modeled employing the Clausius-Clapeyron equation and its development-Chen model. Sorption isotherms showed sigmoidal shape characteristic for high-molecular weight materials. Monolayer moisture content varied between 0.047 and 0.106 g water/g solids. The glass transition temperature of anhydrous green peas increased in from 89.9 to 175.6°C while Tg' value changed from -43.4 to -26.6°C to as a result of 75% polysaccharide addition. The ultimate maximum-freeze-concentration conditions of the powders were observed in range from 0.783 to 0.814 g solids/g sample. Monolayer capacity, Tg and Tg' values increased with increasing maltodextrin amount in the sample which indicates that the addition of starch hydrolysate has a beneficial effect on the stability of powders stored frozen and at room temperature.

Effect of counterions on the water sorption and glass transition properties of maltobionate salts

AbstractThe purpose of this study was to clarify the effect of counterions on the water sorption and glass transition properties of maltobionate salts. Sodium maltobionate (NaMb), potassium maltobionate (KMb), and magnesium maltobionate (MgMb2) were employed, and the values for calcium maltobionate (CaMb2) and maltose were taken from the literature. The water sorption isotherm of the samples was characterized using the Guggenheim-Anderson-de Boer model. The glass transition temperature (Tg) and freeze-concentrated glass transition temperature (Tg’) were evaluated by differential scanning calorimetry. The effect of water content on the Tg was analyzed using the Gordon-Taylor model. The order of the anhydrous Tg values of maltobionate salts was: KMb < NaMb < maltose < MgMb2 < CaMb2. The anhydrous Tg of the divalent cation forms (MgMb2 and CaMb2) was much higher than that of the monovalent cation forms (NaMb and KMb). The anhydrous Tg will be affected by the plasticizing effect and electrostatic effect of cations. The Tg depression induced by water plasticizing was greater for KMb than for the other maltobionate salts. The order of Tg’ values of freeze-concentrated maltobionate salts was: KMb < maltose < NaMb < MgMb2 < CaMb2. This trend was almost the same as that seen for anhydrous Tg, but the range of the Tg’ values (242.2–257.8 K) was much lower than that of the anhydrous Tg (346.9–421.3 K). The Tg’ appears to be affected by the strength of ionic interactions and amount of unfrozen water.

A bridging model of a water-triggered shape-memory effect in an amorphous polymer undergoing multiple glass transitions

Hydrothermally-driven shape memory polymers (SMPs) have been extensively studied due to their advantage of having multiple response capabilities. In these SMPs,bound water reduces their glass transition temperatures (T g) by plasticizing the soft segments to achieve a water-triggered shape-memory effect (SME). However, the effect of bound water on hard segments, which has a synergistic effect on the T g and water-triggered SME of the soft ones, remains largely unexplored. In this study, we propose a new model to explore the working principles and hydrothermally-driven shape memory behaviors of amorphous SMPs. The bound water molecules are first divided into bridging and non-bridging bound water, and then a bridging effect is proposed to convert hard segments into soft ones, thus affecting the T g and water-triggered shape memory behavior in SMPs. An extended Gordon–Taylor model is formulated to identify the effects of bound water weight fraction and T g. Furthermore, a constitutive relationship between strain and relaxation time has been developed to describe the effects of temperature and bound water weight fraction on the hydrothermally-driven shape memory behaviors. Finally, the effectiveness of the proposed models is verified using the experimental results of amorphous SMPs reported in the literature.

PHASE DIAGRAMS OF HYDROLYSATES WITH DIFFERENT DEGREE OF DEPOLYMERIZATION OBTAINED BASED ON CHEMICALLY MODIFIED STARCHES

Background. One of the best ways to present the relationship between phase changes and the stability of food products related to water content and temperature change is a phase diagram. The aim of the pre-sented research was to develop phase diagrams for maltodextrins obtained from native potato starch and acetylated potato starch (E14120) and distarch phosphate (E1412). For this purpose, glass transition curves and freezing curves were determined using the DSC (differential scanning calorimetry) method. As part of the research, an attempt was also made to assess the impact of modification of the original material and the degree of saccharification on the parameters that determine storage stability. Samples with different water activity were obtained by placing dried maltodextrins in an environment with different humidity. The glass transition temperature and freezing temperature were determined using DSC. The results were described using the Gordon and Taylor equation and the Chen equation, and phase diagrams were prepared. Results and conclusions. The glass transition temperature of anhydrous maltodextrins (Tgs) varied in the range of 131.4 ÷ 172.5 ºC depending on the type of modification of base starch and DE. The glass transition temperature (Tg) of all samples decreased with increasing water activity. The obtained values of the k constant of the Gordon-Taylor model ranged from 4.81 to 5.70, and the parameters of the Chen model varied from -0.334 to -0.123 (parameter B) and from 0.074 to 0.117 (parameter E). The values of unfreezable water Xw' (from 0.218 to 0.218 kg of water/kg of sample) and temperature Tm' (from -18.6 to -14.9 °C) and Tg' (from -42.1 to -22.4 °C) determined using a phase diagram for individual maltodextrin samples depended on DE and the type of modification of base starches. The research performed allows us to conclude that native and modified starch hydrolysates were characterized by different thermal proper-ties, which provides wide possibilities of their use in industrial processes.

Systematic Investigation on the Glass Transition Temperature of Binary and Ternary Sugar Mixtures and the Applicability of Gordon-Taylor and Couchman-Karasz Equation.

Glass transition temperatures (Tg) of carbohydrate mixtures consisting of only one monomer and glycosidic binding type (aldohexose glucose, α1-4-glycosidic bonded) were studied by differential scanning calorimetry (DSC). The aim of this work was to systematically assess the predictability of Tg of anhydrous binary and ternary sugar mixtures focusing on the components Tg, molecular chain length, and shape. Binary systems were investigated with glucose as a monosaccharide and its linear di-, tri-, tetra-, penta-, hexa-, and heptasaccharides. Additionally, the Tg of ternary carbohydrate systems prepared with different glucose/maltose/maltotriose mass fractions were studied to evaluate the behavior of more complex mixtures. An experimental method to prepare fully amorphized, anhydrous mixtures were developed which allows the analysis of mixtures with strongly different thermodynamic pure-component properties (Tg, melting temperature, and degradation). The mixtures’ Tg is systematically underestimated by means of the Couchman–Karasz model. A systematic, sigmoidal deviation behavior from the Gordon–Taylor model could be found, which we concluded is specific for the investigated glucopolymer mixtures. At low concentrations of small molecules, the model underestimates Tg, meeting the experimental values at about equimolarity, and overestimates Tg at higher concentrations. These deviations become more pronounced with increasing Tg differences and were explained by a polymer mixture-specific, nonlinear plasticizing/thermal volume expansion effect.

Effect of water sorption on glass transition and microstructural variation of dextran & sugar mixtures

Dextran is widely used as a model polysaccharide to study the interactions between polysaccharides and small molecule sugars. This study examined water sorption isotherms and glass transition temperatures (Tg) of mixtures of dextran with trehalose, lactose and sucrose for understanding how different disaccharides affect dextran's processing adaptation and storage performance relevant to water sorption. At the same chemical composition, monolayer water (m0) was dextran & sucrose (dex&suc) > dextran & trehalose (dex&tre) > dextran & lactose (dex&lac). The higher ratios of dextran, the higher was the Guggenheim constant (C) value of the mixtures. The compatibility of dextran and disaccharides was dex&tre > dex&lac > dex&suc. Gordon–Taylor model showed dex&tre (2:1) best inhibited water plasticization. Furthermore, trehalose and lactose were more effective in preventing morphological changes of hydrous matrices in the mixtures. The crystallinities of samples at 43% relative humidity (RH) were slightly lower than that at 11% RH.

The Thermal Characteristics, Sorption Isotherms and State Diagrams of the Freeze-Dried Pumpkin-Inulin Powders.

Powders based on plant raw materials have low storage stability due to their sorption and thermal properties and generate problems during processing. Therefore, there is a need to find carrier agents to improve their storage life as well as methods to evaluate their properties during storage. Water adsorption isotherms and thermal characteristics of the pumpkin powder with various inulin additions were investigated in order to develop state diagrams. Differential scanning calorimetry (DSC) was used to obtained glass transition lines, freezing curves and maximal-freeze-concentration conditions. The glass transition lines were developed using the Gordon–Taylor model. Freezing data were modeled employing the Clausius–Clapeyron equation and its development–Chen model. The glass transition temperature of anhydrous material (Tgs) and characteristic glass transition temperature of maximum-freeze-concentration (Tg′) increased with growing inulin additions. Sorption isotherms of the powders were determined at 25 °C by the static-gravimetric method and the experimental data was modeled with four different mathematical models. The Peleg model was the most adequate to describe the sorption data of the pumpkin–inulin powders. Guggenheim-Anderson-de Boer (GAB) monolayer capacity decreased with increasing inulin concentration in the sample.

Effect of carbonation and ultrasonication assisted hybrid drying techniques on physical properties, sorption isotherms and glass transition temperature of banana (Musa) peel powder

Banana peels (Cavendish and Nay poovan) in ripe and raw form were dried using tray drying (T), microwave (M), microwave-convection (MC) and freeze drying (F) with ultrasonication (U) and combined treatment of carbonation and ultrasonication (CU) as pretreatments. SEM analysis showed microscopic channels in samples after U treatment, which were more ravine after CU. Based on bulk density, tapped density, porosity, angle of repose, colour parameters, viscosity, CU + F was found best drying combination followed by CU + MC. For selected samples, relative water sorption changes induced by U and CU were positive as the sorption surface area increased after given pre-treatments. Peleg model fitted best to experimental data for sorption studies. The water plasticizing effect of U and CU treatments on glass transition temperature (Tg) was predicted using Gordon-Taylor model. State diagram predicted critical moisture content (Xc), 0.106 kg H2O/kg dry matter and critical water activity (awc), 0.525 at 16 °C.

Water vapour sorption thermodynamic properties and stability of spray dried avocado milkshake powder

Abstract Correlation of sorption and glass transition properties were determined for avocado milk shake powder obtained by spray-drying with varying levels (2,6,12%) of maltodextrin (MD). The isotherms were Type III and GAB model was found to be adequate to predict the sorption data. At 25 °C, the critical water content that ensures the glassy state of the shake powder during storage increased from 0.05 to 0.08 g water/g product while the critical water activity increased from 0.14 to nearly 0.6, yield increased and stickiness decreased with increasing levels of MD (2 to 12%) The correlation between Tg and the water fraction present in the sample was fitted using the Gordon–Taylor model showing satisfactory values of R² ( >0.98). From the combined plot of Tg and EMC vs water activity the critical water activity at 20° C is 0.1 which increased to 0.6 at -5°C.

Evaluation of water sorption isotherm, glass transistion temperature, vitamin C and color stability of mango peel powder during storage

The purpose of this work was to study the physical and chemical stability of the mango peel powder produced by hot-air drying. Sorption isotherms at 25 °C and glass transition temperatures (Tg) of the samples in equilibrium at different aw were determined. The degradation of vitamin C and color parameter b* was evaluated along storage under controlled conditions (relative humidity = 60%, temperature = 10, 25 and 35 °C) during 180 days. GAB model well-described water adsorption of the product, showing a monolayer moisture content (Xm) of 0.1260 g water/g dry solids and a critical aw of 0.56. The Gordon-Taylor model predicted the plasticizing effect of water on glass transition temperature, since Tg of the powders kept at different relative humidity conditions decreased as water activity increased. No visual signs of agglomeration and darkening were observed for samples stored at aw ≤ 0.529. The powders are a source of calcium and rich in potassium, copper, magnesium and manganese. The concentration of inorganic contaminants and pesticide residues were below the maximum allowed limits. The degradation of vitamin C and color parameter b* followed the first and zero-order kinetic models, respectively. The study indicated good stability for the powders along the storage at 10 and 25 °C, which can be incorporated into different food products, showing high retention of vitamin C, phenolic compounds, antioxidant activity and maintenance of color characteristics.

Crystallization and strength analysis of amorphous maltose and maltose/whey protein isolate mixtures.

Maltose is an essential derivative of starch. To understand the processability and stability of maltose-containing foods, material characterization of the phase and state transition from its amorphous state is required. Although the crystallization of amorphous maltose is well understood, few studies have reported the relationship between the crystallization and the glass transition temperature (Tg )-related molecular mobility. In this study, water sorption, crystallization, Tg -related α-relaxation, and the corresponding time factor for amorphous maltose and maltose / whey protein isolate (WPI) mixtures are measured at various water activity (aw ) levels and 25 °C. The water-additive principle for maltose / WPI mixtures was observed at aw ≤ 0.440 at the molecular level, whereas the crystallization of amorphous maltose occurred at high aw values (≥0.534). The crystal formation and crystallization kinetics of amorphous maltose were affected by water and WPI at aw ≥ 0.534 and 25 °C, as determined by X-ray diffraction. The relationship between Tg and the water content was fitted by the Gordon-Taylor model, and its constant showed a compositional dependence for the maltose / WPI mixtures. The α-relaxation temperature of the amorphous samples decreased due to water plasticization, but increased with an increase in the WPI quantity. The Strength (S) value for amorphous maltose, which was a quantitative estimate of the compositional effects on molecular mobility, was based on the William-Landel-Ferry (WLF) equation. The S concept exhibits considerable potential for application in controlling the crystallization of amorphous maltose and improving the processability and stability of maltose-containing foods. © 2020 Society of Chemical Industry.

Study on redispersibility of drug nanocrystals particles during storage: Novel understanding based on water adsorption and glass transition of amorphous matrix formers.

The objective of this study was to understand the influence of the water adsorption and glass transition of matrix formers on redispersibility in water of drug nanocrystals-aggregated particles(NAP) during storage, and the critical storage strategy for NAP powders were determined based on the Guggenheim-Anderson-de Boer (GAB) and the Gordon-Taylor models. Apigenin was used as model drug. Six kinds of matrix formers sucrose(SU), lactose(LA), trehalose(TR), inulin(IN), maltodextrin(MA) and PVPK30(PV) were used to prepare apigenin nanocrystals-aggregated particles (AN-NAPs). The results demonstrated that the adsorption isotherms curves of six kinds of matrix formers based AN-NAPs all showed typical II (S) type adsorption. The water activity significantly influenced the redispersibility of AN-NAP, which could be attributed to the microstructure collapse of amorphous matrix induced by moisture adsorption at high water activity or high moisture. MD based AN-NAP(AN-NAP/MD) exhibited much better redispersibility at high water activity(0.689) compared with the other amorphous matrix formers. MD was able to significantly enlarge the Tg of AN-NAP system and prevent from aggregation of AN-NAP compared to other matrix formers. And the critical water activity and moisture content of AN-NAPs were in the ranges of 0.015-0.545 and 0.0412-0.1508g water/g dry matter, respectively. Of all amorphous matrix based NAPs, the critical water activity of AN-NAP/MD was the highest (0.545), and the critical moisture content was 0.1003g water/g dry matter, and followed by TR based on AN-NAP. MD could be used as an excellent matrix former for nanocrystals-aggregated particles during storage. Therefore, the roles of water adsorption and glass transition of matrix formers on redispersibility of drug nanocrystals-aggregated particles during storage was successful elucidated, and the critical storage strategy was proposed based on the GAB model and the Gordon-Taylor model.

Impact of solid state miscibility on quantitive nano-precipitation of budesonide and PVP-VA.

In the present study, the drug–polymer miscibility and molecular interaction of budesonide in polymers (PVP/VA E 735, 635 and 535) systems were studied, by using three techniques including, calculation of Hansen solubility parameters, analysis of melting points depression, and measurement of glass transition temperature (Tg). Budesonide nanoparticles were prepared by sonication technique. The combined effect of four significant formulation variables, namely, polymer and surfactant concentrations, time and amplitude of sonication on particle size, polydispersity, drug loading and entrapment efficiency of drug was investigated by apply 24 factorial design. The drug/ polymer blend was considered miscible depending on the results of three approaches. The results of calculated values of miscibility parameter (χ) for each pair were negative ranging from - 2.012to -1.948. Single Tg and positive deviation from Gordon-Taylor model for all ratios of drug–polymer binary mixtures. Produced amorphous budesonide nanoparticles, depending on choice of polymer and process parameters contained from 97% to 99% drug, with particle size diameter varying in size from 641-357 nm. It was found that clear evidence on effect VA ratio on percent entrapment efficiency and particle size of budesonide.

Physical, Chemical, Thermal and Microstructural Characterization of Edible Films from Mechanically Deboned Chicken Meat Proteins

Mechanically deboned chicken meat protein concentrate (CMPC) was mixed with 30, 40 and 50% glycerol to produce films and physical, thermal, chemical, morphological and microstructural properties of films were characterized. The apparent porosity of films increased with increasing glycerol content which was due to the increase of free volume in film matrix (P < 0.05). The higher the apparent porosity, the greater the water vapor and oxygen permeability of films were (P < 0.05), which means gas molecules are permeating through pores. Puncture strength of films decreased as glycerol concentration increased, whereas puncture deformation was increased (P < 0.05). Lower glass transition temperature (Tg) observed as glycerol concentration increased, and Tg values of films were well fitted to Gordon-Taylor model as a function of glycerol mass fraction. Higher glycerol concentrations led to decrease of onset temperatures of weight losses, while weight loss increased. Infrared spectra of films showed similar backbone structure, but increasing glycerol concentration affected to peak intensity around 1000–1100 cm−1. All films had low percentage of degree of crystallinity. CMPC films showed lower contact angle than 65° and all films had hydrophilic surfaces. The surface morphology of films showed that films plasticized with 40% glycerol had the lowest roughness value (P < 0.05). Micrographs of films also showed porous surface structure as glycerol concentration increased, and these images supported the results of porosity, mechanical and barrier properties of films. It can be concluded from these results that glycerol at 40% concentration showed the best results when compared with the other two concentrations.

Effect of osmotic dehydration on desorption isotherms and glass transition temperatures of mango

SummaryThe influence of different osmotic solution pretreatments (sucrose and glucose with concentration of 45%) on desorption isotherms and glass transition temperatures (Tg) of mango was investigated. The Peleg model satisfactorily described the relationship between water activity (aw) and moisture content of all samples (0.992 &lt; r2&lt;0.997). The equilibrium moisture content of mangoes osmotically pretreated in sucrose was higher than that of samples pretreated in glucose. Differential scanning calorimetry was used to measure the Tg of samples equilibrated with different aw (0.12–0.75). The dependence of Tg on moisture content was adequately fitted by Gordon–Taylor model (0.946 &lt; r2&lt;0.949). The osmo‐dehydrated mangoes showed lower Tg than fresh samples at the same moisture content. Additionally, the samples osmotically pretreated in glucose showed the lowest Tg value.

Thermodynamic sorption properties, water plasticizing effect and particle characteristics of blueberry powders produced from juices, fruits and pomaces

Fresh blueberries were processed into three powder forms through freeze drying, namely juice powders containing 8% whey protein isolate (WPI), fruit powders and pomace powders. The water binding behaviors of these blueberry powders were studied through thermodynamic sorption analysis, quantification of water plasticizing effect and characterization of particle properties. The GAB model was successful in fitting the water sorption isotherms of blueberry powders at 20, 35 and 50°C. Thermodynamic studies revealed that the sorption processes of all the samples were enthalpy-driven and only the sorption process of blueberry juice powders containing WPI was spontaneous (ΔG<0). Meanwhile, the highest absolute integral entropy values for blueberry juice powders containing 8% WPI, fruit powders and pomace powders were obtained at the moisture contents of 0.011, 0.013 and 0.024kgH2O/kg dried matter, respectively. Furthermore, the plasticizing effect of water on blueberry pomace powders was the weakest, since its k value of Gordon-Taylor model was lower than that of other samples. These results implied that blueberry pomace powders had the weakest affinity with water molecules. Thus, blueberry juice powders containing 8% WPI and fruit powders were suggested to be stored at a lower relative humidity than pomace powders. Besides, it was temporarily found that the difference in water binding capacity among blueberry powders was associated with the distribution of functional groups derived from sugars and acids, as well as the particle size. All the results can be a reference for drying, packaging, storage and distribution of blueberry powders in practical applications.

Thermal characteristics and state diagram of freeze-dried broccoli: Freezing curve, maximal-freeze-concentration condition, glass line and solids-melting

Stability of foods during processing and storage can be determined from their phase and state diagrams. In this study, state diagram of broccoli was developed considering freezing curve, glass line, maximal-freeze-concentration conditions, solids-melting and BET-monolayer line. The freezing point, glass transition and solids-melting were measured and modeled by Chen’s model, Gordon-Taylor model, and Flory-Huggins model, respectively. The ultimate maximal-freeze-concentration conditions (Tm′)u (i.e. end temperature of freezing) and (Tg′′′)u [i.e. end glass transition at (Tm′)u] were found as −30.0°C and −32.2°C, respectively, and solids content (i.e. Xs′) at this point was 0.70g/g sample. The solids-water interaction (χ) during melting was estimated as 0.69 (dimensionless) from Flory-Huggins model, and BET-monolayer was observed as 0.089g/g dry-solids at 20°C.

Glass Transition and State Diagram for Jujube Powders With and Without Maltodextrin Addition

Both water activity and glass transition concepts were used for stability evaluation of jujube powder in this study. The water sorption behaviour at 25, 35 and 45 °C and the relationship between water content (X w), glass transition temperature (T g) and water activity (a w) were investigated for jujube powder with and without the maltodextrin addition. Moisture sorption isotherms of different jujube powders were of type III and BET model was the best for fitting the experimental data. The equilibrium moisture content of jujube powder containing 20% maltodextrin at a given a w was lower than that of pure jujube powder. However, temperature had no significant effect on the moisture sorption of jujube powders. Values of T g of different jujube powders were obtained using differential scanning calorimetry and the glass transition line was fitted to the Gordon-Taylor model. A depression in T g with increasing water content was observed. State diagrams of different jujube powders were established based on the moisture sorption isotherm and the glass transition curve. Results showed that jujube powders with and without maltodextrin addition were stable at 25 °C when the water content was lower than 0.0673 and 0.0566 g/g solid, respectively.

Physical properties of spray dryedStenocereus griseuspitaya juice powder

AbstractThe aim of this work was to analyze the effect of spray drying conditions on the physical properties of pitaya juice powder using a 23factorial design. Independent variables were inlet air temperature (150 and 180°C), feed flow rate (1.5 and 2 L/hr), and the amount of encapsulants (60 and 90%). The spray process was performed on pilot‐scale spray dryer and maltodextrin/pectin combination was used as encapsulating material. Moisture content, yield, color, water adsorption, glass transition temperature, and morphology of pitaya juice powders were analyzed. Critical conditions of storage, at which the glass transition occurs were determined. Experimental results showed that all the individual factors had a significant effect on moisture content and color, however, yield was only affected by feed flow rate and percentage of encapsulants. Lower drying temperatures (150°C) favored higher yield of 59% and privileged red‐violet color retention during spray drying. The GAB and Gordon‐Taylor models gave good fit for the experimental data of adsorption isotherms and glass transition temperatures, respectively.Practical ApplicationsIn this work betalains with compounds including nutraceutical properties, which can be used as a dye, were encapsulated. The knowledge of the properties of natural products, with potential either as an additive or as a colorant, is of great significance for applications in both the food and pharmaceutical industry. The efficiency, color, morphology of powders, and properties influencing hygroscopicity, collapse, compression, and agglomeration were determined. These factors control the processability, handling properties, and the stability of pitaya powders.

Effect of different DE values of malto-dextrin on properties for Schisandrae Chinensis Fructus spray-dried powder

The purpose of this study was to compare the effect of different DE values of malto-dextrin on Schisandrae Chinensis Fructus spray-dried powder. The glass transition temperature (Tg) of the spray-dried powder, powder properties and microscopic morphology were determined, and then the moisture absorption isotherms and the glass transition temperature were used to predict its storage stability. The study showed that after adding malto-dextrin, the powder rate was increased; moisture content was decreased; Tg was increased; mobility got better; produced spherical microstructure; and Tg was increased with the decrease of DE value. The water activity-equilibrium moisture content (aw-EMC) relationship in GAB models showed, the moisture absorption of powder was increased with the rising of DE value; and the equilibrium moisture content-glass transition temperature (EMC-Tg) relationship in Gordon-Taylor models showed that, Tg was decreased with the increase of moisture content. As a result, the storage critical condition of the spray-dried powder was improved, and along with the decrease of DE value, the critical water activity and the critical water content were increased. Therefore, the smaller the DE value, the greater the stability of the spray-dried powder.