Gordon-Taylor Equation Research Articles

Controlling the switching temperature of biodegradable shape memory polymers composed of stereocomplex polylactide / poly(d,l-lactide-co-ε-caprolactone) blends

We synthesized new biodegradable shape-memory polymers (SMPs) by blending synthesized poly(d,l-lactide-co-ε-caprolactone) (PLCL) and stereocomplex polylactide (sc-PLA) to be used as biomaterials for medical devices. PLCL copolymers (Mn ∼80,000) with various monomer ratios (LA:CL) were synthesized by the bulk ring-opening polymerization. The glass transition temperature of the resulting PLCL copolymers could be well controlled from −3 °C to 60 °C, agreeing well with the values by the Gordon-Taylor equation, confirming the homogeneous random distribution of LA and CL monomers in the synthesized PLCL. The synthesized PLCL and sc-PLA were eventually blended for the fabrication of biodegradable SMPS. The PLCL/sc-PLA blend samples possessed the sc-PLA crystallinity of ∼13%, which effectively worked as crosslinkings, exhibiting shape-memory behavior with various switching temperatures (30.5°C–62 °C) and shape-recovery ratios realized by adjusting the CL ratio of the PLCL copolymers: a lower CL ratio resulted in a higher switching temperature and a higher shape-recovery ratio.

Improved solubility and permeability of both nifedipine and ketoconazole based on coamorphous formation with simultaneous dissolution behavior

Coamorphous formation between the hydrophobic drugs nifedipine (NIF) and ketoconazole (KTZ) was investigated with the expectation of improving the solubility and permeability of the two compounds. NIF and KTZ spray-dried particles (SDPs) were prepared in a range of NIF/KTZ molar ratios (3/1-1/3). All NIF/KTZ SDPs were in an amorphous state with a single glass transition temperature (Tg). The Tg value of NIF/KTZ (1/1) SDPs showed the largest positive deviation from the theoretical Tg values calculated by the Gordon–Taylor equation, resulting in NIF/KTZ (1/1) SDPs having the highest physical stability at 40°C and 75% relative humidity. The Fourier transform infrared spectroscopy spectra of NIF/KTZ SDPs suggested hydrogen bonding between the NH group of NIF and the tertiary amine group of KTZ. These findings suggest a coamorphous formation between NIF and KTZ at a molar ratio of 1/1 through hydrogen bonding in the solid state. The investigation of the dissolution profiles of NIF and KTZ from NIF/KTZ SDPs showed that NIF/KTZ (1/1) SDPs exhibited supersaturation and had the highest improved solubility of both drugs. NIF/KTZ (1/1) SDPs showed simultaneous dissolution and precipitation of NIF and KTZ, whereas NIF/KTZ (2/1) and NIF/KTZ (1/2) SDPs had different dissolution profiles, suggesting that hydrogen bonding between NIF and KTZ can be maintained in an aqueous solution. Furthermore, the improved permeabilities of both drugs through coamorphous formation were observed in a permeation study using the Caco-2 cell line. The permeated amounts of NIF and KTZ from NIF/KTZ (1/1) SDPs were 2.3- and 3.6-fold higher than those of the individual drug crystals, respectively. This study revealed that coamorphous formation between hydrophobic drugs has a high potential to enhance solubility and improve the membrane permeability of both drugs.

Maltodextrin improves physical properties and volatile compound retention of spray-dried asparagus concentrate

Traditional hot air drying of asparagus is known to lead to a powder with a poor aroma profile. We here concentrated asparagus juice into asparagus concentrate (21.7% w/w) and spray-dried it with maltodextrin DE12 as carrier agent to improve the volatile profiles of asparagus powder and to valorise fresh asparagus side-streams. We performed headspace GC-MS with untargeted metabolomics to assess the overall metabolite profile of the spray-dried asparagus powders and identified 70 volatile compounds. The maltodextrin content was positively correlated to the retention of an asparagus key odorant 1-octen-3-ol, as well as other alcohols and aldehydes. Nevertheless, drying conditions had limited effect on the volatile retention of the powders. Moreover, higher outlet temperatures increase the presence of volatiles that were formed during drying, such as 3-methylthio-propanal. From our analyses, it was further found that an increased concentration of maltodextrin was correlated to a lower moisture content, a higher glass transition temperature (Tg) and a narrower size distribution of the spray-dried powders. The Tg of all powders was described with the Gordon-Taylor equation for multicomponent mixtures, and we found a minimum weight fraction of 0.67 (w/dw) maltodextrin required to obtain glassy asparagus powder for storing at ambient conditions.

Physical stability of hydroxypropyl methylcellulose-based amorphous solid dispersions: Experimental and computational study.

The preparation of an amorphous solid dispersion (ASD) is a promising strategy for improving the poor oral bioavailability of many active pharmaceutical ingredients (APIs). However, poor predictability of ASD long-term physical stability remains a prevalent problem. The purpose of this study was to evaluate and compare the predictive performance of selected models concerning solid-liquid equilibrium (SLE) curve and glass-transition temperature (Tg) line modeling of ibuprofen (IBU) in cellulosic polymers (i.e., hydroxypropyl methylcellulose (HPMC) and hydroxypropyl methylcellulose acetate succinate (HPMCAS)). For SLE curve modeling, an empiricalanalyticalapproach(Kyeremateng et al., 2014)and the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EOS) were chosen. Due to the unavailability of PC-SAFT parameters for both polymers, an approximation procedure for parametrization was applied. The Gordon-Taylor equation and Kwei equation were considered for Tg line determination. The impact of various computational set-ups (e.g., model parametrization or extrapolation length) on IBU solubility prediction at storage conditions was thoroughly investigated, assessed and confronted with the results from an 18-month physical stability study. IBU developed stable 20wt% API content ASDs with both HPMC and HPMCAS.The extrapolation behavior and subsequent ASD thermodynamic stability prediction at storage conditions deduced from the aforementioned models weresignificantly different. Overall, the PC-SAFT EOS predicted higher IBU solubility in both polymers and, thus, a lower recrystallization tendency when compared to the empirical analytical approach. At higherIBU concentrations, liquid-liquid demixing inIBU-polymer systems was predicted by the PC-SAFT EOS, which was in qualitative disagreement with experimental observation.

Freeze-concentrated glass-like transition temperature of carbohydrate–phosphate buffered saline systems and impact on collapse of freeze-dried solids

Phosphate buffered saline (PBS) and carbohydrates are used to freeze-dried biomaterials. It has been suggested that PBS reduces the freeze-concentrated glass-like transition temperature ( $$T_{\text{g}}^{\prime }$$ ) of carbohydrate solutions and that freeze-dried solids collapse readily during freeze-drying. In order to obtain more insight into the subject, the effect of PBS on the $$T_{\text{g}}^{\prime }$$ of trehalose solution was systematically investigated. The $$T_{\text{g}}^{\prime }$$ of trehalose solution was found to be independent of the trehalose content. The $$T_{\text{g}}^{\prime }$$ of trehalose–PBS solution, on the other hand, decreased with decreasing trehalose content. The behavior was described as a $$T_{\text{g}}^{\prime }$$ curve for a trehalose–PBS pseudobinary system. The $$T_{\text{g}}^{\prime }$$ curve was analyzed using the modified Gordon–Taylor equation, and the $$T_{\text{g}}^{\prime }$$ of PBS was extrapolated to be 195.0 K. In order to compare the plasticizing effect of PBS, the $$T_{\text{g}}^{\prime }$$ values of other carbohydrate materials including sugar alcohols (glucose, maltitol, sucrose, inulin, and maltodextrin) were also investigated. It was found that freeze-concentrated trehalose was more sensitive to the plasticizing effect of PBS than the other sugars. Finally, trehalose and trehalose–PBS solutions with varying trehalose content were freeze-dried, and their water activity (aw) and apparent volume ratio against pre-dried (frozen) solids (VFD VF−1 ) were evaluated. Freeze-dried trehalose samples had low aw values and high VFD VF−1 values. Freeze-dried trehalose–PBS samples, on the other hand, had significantly higher aw values and lower VFD VF−1 values than freeze-dried trehalose samples depending on the trehalose content. These results corresponded to the $$T_{\text{g}}^{\prime }$$ and initial solute content.

Exploring the physical stability of three nimesulide–indomethacin co-amorphous systems from the perspective of molecular aggregates

Co-amorphization of drugs has been a promising approach to enhance the apparent solubility and dissolution rate of poorly-water soluble drugs. Nimesulide, a BCS Ⅱ drug, was combined with indomethacin to form three co-amorphous systems at molar ratios of 2:1, 1:1 and 1:2 via quench cooling. The aim of this research was mainly to probe the relationship between physical stability (long-term stability and temperature sensitivity) and intermolecular interaction modes among three co-amorphous systems. The calculated glass transition temperature by the Gordon-Taylor equation shows the presence of intermolecular interactions within co-amorphous systems. FTIR spectra further verify that there are hydrogen bonds and π–π stacking in intermolecular interactions. Specific atomic groups involved in the intermolecular hydrogen bonding were investigated using radial distribution function analysis based on molecular dynamic simulation. Gaussian calculation visually gives dominant molecular aggregate composed of multiple hydrogen bonding modes in co-amorphous systems and explains the stability difference of 1:2>1:1>2:1. Finally, powder dissolution profiles were conducted and the 1:2 system has the greatest dissolution advantage with six-fold improvement of dissolution rate compared with pure NMS.

Determination of the Optimal Molar Ratio in Amino Acid-Based Coamorphous Systems.

Coamorphous drug formulations are a promising approach to improve solubility and bioavailability of poorly water-soluble drugs. On the basis of theoretical assumptions involving molecular interactions, the 1:1 molar ratio of drug and coformer is frequently used as "the optimal ratio" for a homogeneous coamorphous system (i.e., the coamorphous system with the highest physical stability and, if strong interaction is possible between two molecules, the highest glass transition temperature (Tg)). In order to more closely investigate this assumption, l-aspartic acid (ASP) and l-glutamic acid (GLU) were investigated as coformers for the basic drug carvedilol (CAR) at varying molar ratios. Salt formation between CAR with ASP or GLU was expected to occur at the molar 1:1 ratio based on their chemical structures. Interestingly, the largest deviation between the experimental Tg and the theoretical Tg based on the Gordon-Taylor equation was observed at a molar ratio of around 1:1.5 in CAR-ASP and CAR-GLU systems. In order to determine the exact value of the ratio with the highest Tg, a data fitting approach was established on thermometric data of various CAR-ASP and CAR-GLU systems. The highest Tg was found to be at CAR-ASP 1:1.46 and CAR-GLU 1:1.43 mathematically. Spectroscopic investigations and physical stability measurements further confirmed that the optimal molar ratio for obtaining a homogeneous system and the highest stability can be found at a molar ratio around 1:1.5. Overall, this study developed a novel approach to determine the optimal ratio between drug and coformers and revealed the influence of varying molar ratios on molecular interactions and physical stability in coamorphous systems.

Assessment of the protective effect of PMMA on water immersion ageing of flame retarded PLA/PMMA blends

The incorporation of PMMA into phosphorus-containing flame retarded PLA was assessed as a possible strategy to reduce the sensitivity of the material to ageing in water at 70 °C. PLA and PMMA are miscible and the unique glass transition temperature can be easily controlled by a proper amount of PMMA according to Gordon-Taylor equation. Water penetration as well as phosphorus release was reduced when incorporated PMMA amount increased. Consequently, the ability to form char and the fire performances measured in cone calorimeter were further preserved. Nevertheless, an efficient protective effect was only observed when PMMA incorporation allows the glass transition temperature in the blend to increase above the ageing temperature. This is achieved for a weight ratio PMMA/PLA no lower than 1.

Solid state nuclear magnetic resonance studies of hydroxypropylmethylcellulose acetyl succinate polymer, a useful carrier in pharmaceutical solid dispersions.

Hydroxypropylmethylcellulose (HPMC) acetyl succinate (HPMC-AS) is a key polymer used for the enablement of amorphous solid dispersions (ASDs) in oral solid dosage forms. Choice of the appropriate grade within the material is often made empirically by the manufacturer of small-scale formulations, followed by extensive real time stability. A key factor in understanding and predicting the performance of an ASD is related to the presence of hydrogen (or other) bonds between the polymer and active pharmaceutical ingredient (API), which will increase stability over the parameters captured by miscibility and predicted by the Gordon-Taylor equation. Solid state nuclear magnetic resonance (NMR) is particularly well equipped to probe spatial proximities, for example, between polymer and API; however, in the case of HPMC-AS, these interactions have been sometimes difficult to identity as the carbon-13 NMR spectra assignment is yet to be firmly established. Using feedstock, selectively substituted HPMC polymers, and NMR editing experiments, we propose here a comprehensive understanding of the chemical structure of HPMC-AS and a definitive spectral assignment of the 13 C NMR spectra of this polymer. The NMR data also capture the molar ratios of the acetate and succinate moieties present in HPMC-AS of various grades without the need for post treatment required by chromatography methods commonly use in pharmacopoeia. This knowledge will allow the prediction and measurement of interactions between polymers and APIs and therefore a rational choice of polymer grade to enhance the solid state stability of ASDs.

The Cooling Rate- and Volatility-Dependent Glass-Forming Properties of Organic Aerosols Measured by Broadband Dielectric Spectroscopy.

Glass transitions of secondary organic aerosols (SOA) from liquid/semisolid to solid phase states have important implications for aerosol reactivity, growth, and cloud formation properties. In the present study, glass transition temperatures (Tg) of isoprene SOA components, including isoprene hydroxy hydroperoxide (ISOPOOH), isoprene-derived epoxydiols (IEPOX), 2-methyltetrols, and 2-methyltetrol sulfates, were measured at atmospherically relevant cooling rates (2-10 K/min) by thin film broadband dielectric spectroscopy. The results indicate that 2-methyltetrol sulfates have the highest glass transition temperature, while ISOPOOH has the lowest glass transition temperature. By varying the cooling rate of the same compound from 2 to 10 K/min, the Tg of these compounds increased by 4-5 K. This temperature difference leads to a height difference of 400-800 m in the atmosphere for the corresponding updraft induced cooling rates, assuming a hygroscopicity value (κ) of 0.1 and relative humidity less than 95%. The Tg of the organic compounds was found to be strongly correlated with volatility, and a semiempirical formula between glass transition temperatures and volatility was derived. The Gordon-Taylor equation was applied to calculate the effect of relative humidity (RH) and water content at five mixing ratios on the Tg of organic aerosols. The model shows that Tg could drop by 15-40 K as the RH changes from <5 to 90%, whereas the mixing ratio of water in the particle increases from 0 to 0.5. These results underscore the importance of chemical composition, updraft rates, and water content (RH) in determining the phase states and hygroscopic properties of organic particles.

Theory for Glassy Behavior of Supercooled Liquid Mixtures.

We present a model for glassy dynamics in supercooled liquid mixtures. Given the relaxation behavior of individual supercooled liquids, the model predicts the relaxation times of their mixtures as temperature is decreased. The model is based on dynamical facilitation theory for glassy dynamics, which provides a physical basis for relaxation and vitrification of a supercooled liquid. This is in contrast to empirical linear interpolations such as the Gordon-Taylor equation typically used to predict glass transition temperatures of liquid mixtures. To understand the behavior of supercooled liquid mixtures we consider a multicomponent variant of the kinetically constrained East model in which components have a different energy scale and can also diffuse when locally mobile regions, i.e., excitations, are present. Using a variational approach we determine an effective single component model with a single effective energy scale that best approximates a mixture. When scaled by this single effective energy, we show that experimental relaxation times of many liquid mixtures all collapse onto the "parabolic law" predicted by dynamical facilitation theory. The model can be used to predict transport properties and glass transition temperatures of mixtures of glassy materials, with implications in atmospheric chemistry, biology, and pharmaceuticals.

Insight into the Dissolution Molecular Mechanism of Ternary Solid Dispersions by Combined Experiments and Molecular Simulations.

With the increase concern of solubilization for insoluble drug, ternary solid dispersion (SD) formulations developed more rapidly than binary systems. However, rational formulation design of ternary systems and their dissolution molecular mechanism were still under development. Current research aimed to develop the effective ternary formulations and investigate their molecular mechanism by integrated experimental and modeling techniques. Glipizide (GLI) was selected as the model drug and PEG was used as the solubilizing polymer, while surfactants (e.g., SDS or Tween80) were the third components. SD samples were prepared at different weight ratio by melting method. In the dissolution tests, the solubilization effect of ternary system with very small amount of surfactant (drug/PEG/surfactant 1/1/0.02) was similar with that of binary systems with high polymer ratios (drug/PEG 1/3 and 1/9). The molecular structure of ternary systems was characterized by differential scanning calorimetry (DSC), infrared absorption spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Moreover, molecular dynamic (MD) simulations mimicked the preparation process of SDs, and molecular motion in solvent revealed the dissolution mechanism of SD. As the Gordon-Taylor equation described, the experimental and calculated values of Tg were compared for ternary and binary systems, which confirmed good miscibility of GLI with other components. In summary, ternary SD systems could significantly decrease the usage of polymers than binary system. Molecular mechanism of dissolution for both binary and ternary solid dispersions was revealed by combined experiments and molecular modeling techniques. Our research provides a novel pathway for the further research of ternary solid dispersion formulations.

Amorphous binary dispersions of chloramphenicol in enantiomeric pure and racemic poly-lactic acid: Morphology, molecular relaxations, and controlled drug release.

We characterize amorphous solid dispersions (ASDs) of the Chloramphenicol antibiotic in two biodegradable polylactic acid polymers, namely a commercial sample of enantiomeric pure PLLA and a home-synthesized PDLLA copolymer, investigating in particular the effect of polylactic acid in stabilizing the amorphous form of the drug and controlling its release (e.g. for antitumoral purposes). Broadband dielectric spectroscopy and differential scanning calorimetry are employed to study the homogeneity, glass transition temperature and relaxation dynamics of solvent-casted ASD membranes with different drug concentrations. We observe improved physical stability of the ASDs with respect to the pure drug, as well as a plasticizing effect of the antibiotic on the polymer, well described by the Gordon-Taylor equation. The release of the active pharmaceutical ingredient from the films in a simulated body fluid is studied by UV/vis spectroscopy at two different drug concentrations (5 and 20% in weight). The amount of released drug is found to be proportional to the square root of time, with proportionality constant that is almost the same in both dispersions, despite the fact that the relaxation time and thus the viscosity of the two samples differ by four orders of magnitude at body temperature. Since the drug release kinetics does not display a significant dependence on the drug content in the carrier, it may be expected to remain roughly constant during longer release times.

Spray-dried xylooligosaccharides carried by gum Arabic

Prebiotic xylooligosaccharides (XOS) are derived from xylan-rich agricultural residues and have important applications in the food, pharmaceutical, and cosmetic fields. The high hygroscopicity and low glass transition temperature (Tg) of XOS could result in operating problems and deterioration of product quality during the drying process and storage, so it is important to enhance physicochemical properties of dried product for improve XOS quality. The objectives of this work were spray drying XOS and comprehensive studying their rheological properties, physicochemical, and morphological characterization, when carried by gum Arabic (GA). The antioxidant effects of the products were evaluated by 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2′-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS+), ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC). The intuitive perturbation plot was applied to analyse the effects of the independent variables on the responses. A polynomial equation and the Gordon-Taylor equation were used to model the experimental data, and the fitted equations revealed the powder quality and storage stability well (R2> 0. 95). The molecular weight of the carbohydrate affected the rheological properties and Tg. Increasing the solid content of the initial solution tended to increase the apparent viscosity and median diameter. The EC50 values of representative products were 1126.00 and 651.69 μg/mL by DPPH and ABTS+ assays, and antioxidant activity values of representative products were 49.68 and 64.95 μmol TE/g by FRAP and ORAC assays, which shown the remarkable antioxidant effects. The drying yield, hygroscopicity, Tg, microencapsulating efficiency, and colour attributes (L*, a*, and b*) of representative high GA concentration (GAC) products were 76.10%, 13.00 g H2O/100 g dry weight, 71.10°C, 99.69%, 96.93, 1.13, and 3.66, respectively, which shown better quality properties than low GAC products. According to the X-ray diffraction and scanning electron microscopy analysis, the microparticles were amorphous, and well-separated under an appropriate GAC. The Fourier transform infrared spectra results shown that the XOS and GA preserved their structural integrity during the spray drying process.

Elucidating the relationship between states of water and ion transport properties in hydrated polymers

Ions transport properties in hydrated polymers is usually correlated with the amount of water assuming that all water contributes equally. Herein, we demonstrate that water in polymers exists in three states (non-freezable, intermediate, and free water), and the different states of water exert different impacts on polymer properties including glass transition temperature and ion sorption and diffusion. We synthesized four systematic series of polymer networks including neutral, zwitterionic, cation exchange, and anion exchange polymers. The amounts of water in different states in the hydrated polymers were determined using Differential Scanning Calorimetry (DSC), and their dependence on the polymer composition is investigated. The glass transition temperature of the hydrated polymers is satisfactorily correlated with the non-freezable water using the Gordon-Taylor equation. The salt solubility is correlated with the combined free and intermediate water, and the salt diffusivity is satisfactorily correlated with the total water using the modified Yasuda model.

Effect of water content on the glass transition and textural properties of hazelnut

This study is based on the assumption that the change in the texture of hazelnut, induced by water sorption or desorption, can be derived from the glass transition. No previous study has investigated the glass transition properties of hazelnuts. This study aimed to investigate the effect of water content on the glass transition and textural properties of a roasted hazelnut product. Water content of the sample was adjusted in various relative humidity conditions, and the mechanical glass transition temperature Tg was investigated using thermal rheological analysis (TRA), a type of thermomechanical analysis. The TRA curve exhibited a clear force drop induced by the glass transition, and mechanical Tg of the samples was determined. Water plasticizing effect caused mechanical Tg to decrease as the water content increased. The reduction in Tg was analyzed using the Gordon–Taylor equation and linear equation, and the critical water contents (water content at mechanical Tg = 25 °C) were obtained. The fracturing properties of the hazelnut changed from brittle to ductile at the critical water contents. This suggested that the change in the texture of hazelnut can be characterized by the glass transition.

Investigation of miscibility estimation methods between indomethacin and poly(vinylpyrrolidone-co-vinyl acetate)

The investigation of the miscibility between active pharmaceutical ingredients (API’s) and polymeric excipients is of great interest for the formulation and development of amorphous solid dispersions, especially in the context of the prediction of the stability of these systems. Two different methods were applied to determine the miscibility between model compounds poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA) and indomethacin (IND), viz. the measurement of the glass transition temperature (Tg) and the melting point depression method framed on the Flory-Huggins theory. Measurement of the glass transition temperatures of the binary blends showed the formation of an amorphous single phase system between the PVPVA and the IND regardless of the composition. Variation of Tg with the composition was well described by the Gordon-Taylor equation leading to the error of concluding lack of intermolecular interactions between the materials. Application of the Brostow-Chiu-Kalogeras-Vassilikou-Dova (BCKV) model shows a negative interaction parameter (a0) suggesting the presence of drug-drug intermolecular interactions. Application of the melting point depression method within the framework of the Flory-Huggins theory proved the miscibility of the system at temperatures close to the melting point of IND.

Organic acids as co-formers for co-amorphous systems – Influence of variation in molar ratio on the physicochemical properties of the co-amorphous systems

Co-amorphous drug delivery systems are attracting increasing attention in the pharmaceutical field, due to their promising potential to improve the solubility and bioavailability of poorly water-soluble drugs. In this study, three organic acids, namely benzoic acid, malic acid and citric acid, were investigated as co-formers for the weakly basic drug carvedilol. It was hypothesised that the mono-, di- and triprotic nature of the organic acids could result in co-amorphous salt formation with carvedilol at the respective stoichiometric molar ratios, leading to different physicochemical properties of the co-amorphous samples. The carvedilol-organic acid samples were spray dried at molar ratios from 1:4 to 4:1 and amorphous products were obtained for all mixtures except for carvedilol-benzoic acid at a molar ratio of 1:4. A positive deviation of the glass transition temperature compared to the Gordon-Taylor equation was seen for all co-amorphous samples. Salt formation was confirmed by FTIR, but interestingly complete salt formation did not simply follow the molar ratio of the number of basic and acidic groups, most likely due to steric hindrance. As more than one molecule of carvedilol was found to be involved in most co-amorphous systems with the organic acids, this approach allows for a higher “drug loading” compared to other co-formers that usually form co-amorphous systems at a 1:1 M ratio. In addition, the large number of available organic acids offers various options for selecting co-formers.

State Diagram of Crystallized Date-Syrup: Freezing Curve, Glass Transition, Crystals-Melting and Maximal-Freeze-Concentration Condition

ABSTRACT State diagram of crystallized date-syrup was developed based on the freezing curve, glass transition curve, sugar crystals-melting curve, maximal-freeze-concentration condition, and eutectic point. The freezing point, glass transition, and sugar crystal-melting curves were modeled by Chen’s model based on Clausius-Clapeyron equation, Gordon-Taylor equation and Flory-Huggins equation, respectively. The ultimate maximal-freeze-concentration condition was determined as -42.8 °C [i.e. (Tm′)u, end point of freezing curve]. The intersection point on the freezing curve from the vertical line passing through the end point of freezing [i.e. (Tm′)u] as Xs′ [i.e. 0.73 g/g sample (i.e. un-freezable water as 0.27 g/g sample)]. The eutectic temperature and solutes content at eutectic point were determined as -10.2 °C and 0.39 g/g sample, respectively.

Using model food systems to develop mathematical models for construction of state diagrams of fruit products

The parameters of the Gordon-Taylor equation (Tgs, k), the Chen equation (E,B) and the maximally freeze-concentrated phase (Tm', Tg’xs') have been regarded as necessary data for construction of state diagrams of sugar-rich foods. These parameters are significantly influenced by the sugar mass fractions; thus mathematical models for constructing the state diagram parameters based on the type and mass fraction of the main solutes of fruits are required. Experiments using model food systems and validation experiments using fruit juices were designed in this work with the purpose of developing, calibrating and validating the performance of mathematical models. Differential Scanning Calorimetry (DSC) was used to evaluate the thermal transitions of 19 model food systems with well-controlled chemical composition and of 5 fruit juices. Mathematical expressions of Tgs,k,E,B,Tg',Tm',xs' as a function of mass fraction of fructose (XF), glucose (XG), sucrose (XS), pectin (XP) and citric acid (XA) and their interactions were developed. A statistical validation (α = 0.05) showed that solute composition-based mathematical models developed in this study are suitable and accurate for construction of state diagrams of real sugar-rich foods in which only the knowledge of their solid mass fraction is required.