Sorption Isotherm Curves Research Articles

Study of moisture sorption thermodynamic in canola oilseed and drying energy requirement considerations

AbstractThe objective of this study is to derive the thermodynamic characteristics from sorption isotherm data for canola. The semi‐gravimetric method was utilized at three different temperatures (25, 40, and 55°C) and seven air relative humidity levels within the range of 11%–90%. The observed data indicated that the equilibrium moisture content of the sample decreased as the temperature increased. The “GAB and BET” models were applied to fit the empirical data, which demonstrated a Type III isotherm, and the monolayer water content was subsequently determined using these models. Thermodynamic properties such as “isosteric heat,” “net isosteric heat,” “differential entropy,” “net integral entropy,” and “net integral enthalpy” were determined from isothermal sorption curves. The results show that as moisture content increases, both the sorption isosteric heat and the differential entropy of sorption decrease. This indicates that at higher moisture levels, the energy required for additional moisture adsorption and the changes in entropy are reduced. Similarly, the net isosteric heat of sorption and the net integral enthalpy of sorption also decrease with increasing moisture content, consistent with the observed reductions in isosteric heat and differential entropy. The specific absorption surface area for each temperature was determined by calculating the monolayer moisture content using both the “GAB and BET models.” The net integral entropy had an increasing trend in the range of 4%–4.5% (db%), while it decreased in the range of 4.5%–6.8% of moisture content. In addition, the spreading pressure at three levels of temperature was reported. Finally, an empirical relation was employed to illustrate the cumulative energy requirement for drying versus moisture content. The results indicated that at low moisture content levels, the drying process required significantly higher energy.Practical applicationsMoisture sorption isotherms are essential for understanding the interaction between water and food ingredients. This knowledge is vital for improving food processing methods such as drying, mixing, cooling, and storage. In industry, isotherms can help determine the best drying method to maintain food quality, identify the optimal mixing conditions to ensure consistency, establish cooling protocols to prevent spoilage, and set storage guidelines to extend shelf life. In addition, understanding thermodynamic properties is crucial for regulating moisture absorption and release, achieving the desired food texture, managing surface characteristics, and calculating the energy needed for effective dehydration processes.

Functional instant noodle formulation for emergency conditions: Sensory and stability characteristics.

The aim of this study was to evaluate the shelf-life and sensory characteristics of a functional instant noodle preparation designed to be used in emergencies as a tactical ration. Instant noodles were selected for their global acceptability and ease of preparation. In this study, semolina flour was used as the main ingredient, and soy protein isolate was added to increase the protein content. Additionally, green tea and beef tallow were incorporated to decrease the likelihood of oxidation. Carboxymethyl cellulose was added to increase the porosity and water absorption of the dry noodles. Spirulina powder was used as a dressing for the final product before serving to increase the nutritional value and provide the consumer with the required vitamins and minerals of the day. Physical, chemical, and organoleptic properties were assessed at multiple timepoints in a 120-day period to perform an accelerated shelf-life test by determining their critical moisture content and moisture sorption isotherm curves at 30, 45, and 55°C. The shelf-life of the product was evaluated to be 1197.28 days at 30°C and 75% relative humidity in aluminum pouches. In conclusion, the product is shelf-stable at room temperature and is recommended to be stored and used in disaster conditions such as earthquakes, floods, and wars.

Sorption Kinetics and Equilibrium Isotherms of Phosphine Gas into Wheat Kernels

Highlights The pseudo-first order kinetic model fits well with the experimental data of sorbed phosphine versus time. Sorption isotherm curves were developed using Langmuir, Freundlich, and Redlich-Peterson models. Phosphine adsorption capacity of wheat kernels increased with increase in applied concentration (400-2400 ppm). Abstract. Phosphine (PH3) is the most used fumigant in the U.S. due to its low price, ease of use, and wide accessibility. With the growing concerns of phosphine-resistant insect pests, the sustainability of PH3 as an effective fumigant has been put at risk. Sorption equilibrium data is critical for improving the accuracy of modeling studies for phosphine-wheat fumigation systems and would clarify the PH3 uptake and sorption capacity of wheat. The objectives of this study were to determine the effect of initial concentration (from 400 to 2400 ppm) on the equilibrium concentration for PH3 in wheat kernels and on cumulative and daily PH3 sorption through time. Kinetic data showed the sorption process was time-dependent and occurred in two phases: an initial faster adsorption phase, followed by a phase with a slower sorption rate as the grain and PH3 reached equilibrium. Pseudo-first and pseudo-second order models were fit to PH3 concentrations versus time experimental data. The pseudo-first order model provided better equilibrium estimates and was used for the sorption isotherm analysis. Langmuir, Freundlich, and Redlich-Peterson sorption isotherm models were fit to the plot of equilibrium headspace gas concentration versus sorbed PH3 quantity. All three models had low standard errors of prediction (0.46-0.47). These PH3 sorption kinetics and values of total sorbed quantity at equilibrium are valuable for modeling the rate and maximum quantity of PH3 uptake in wheat. Keywords: Fumigation, Kinetics, Phosphine, Sorption Isotherm, Wheat.

Pendugaan umur simpan kerupuk sagu goreng dengan pendekatan kurva isoterm sorpsi air [Shelf-life estimation of fried sago crackers by water sorption isotherm curve approach

Fried sago crackers are dry local foods easily damaged by moisture during storage. To increase economic value and open commercialization opportunities, a study aimed to estimate the shelf life of white and red fried sago crackers using an acceleration method based on the water sorption isotherm curve. Estimating the shelf life was carried out by storing crackers in several modified jars containing different saturated salt solutions. Calculating the moisture permeability constant of polyethylene and polypropylene packaging was also carried out to support the necessary data. The results showed that sago crackers packaged in polypropylene had a longer shelf life than polyethylene plastic. The white sago crackers with polypropylene plastic had a shelf life of 19.89-69.83 days at 70-90% RH, while polyethylene was 12.02-42.21 days at 70-90% RH with 0.0434 g H2O.g solid-1 critical water content. The red sago crackers with polypropylene plastic had a shelf life of 18.26-69.93 days at 70-90% RH, while polyethylene was 11.04-42.27 days at 70-90% RH with a critical water content of 0.0455 g H2O.g solid-1. The chosen model for the water sorption isotherm curve was Hasley and GAB, with equation log (ln (1/aw)=-1.82-1.31 log Me for white sago fried crackers and Me=(0.5157aw)/(1-0.9632aw)(1+15.578aw) for red sago fried crackers, respectively. Fried sago crackers in polypropylene plastic packaging have the potential to be developed as local food products with a longer shelf life.

Deep eutectic solvents (DESs) films based on gelatin as active packaging for moisture regulation in fruit preservation

To develop a novel active packaging for fruit preservation, two different deep eutectic solvents (DESs) comprising choline chloride, betaine and glycerol [ChCl:Gly (1:2) and Be:Gly (1:2)] were prepared and the corresponding DESs-based films (DES@Gel) using gelatin as polymer matrix were fabricated. DES@Gel showed smoother morphologies and better optical and mechanical properties as compared with Gel. Moisture sorption isotherm curves, the enhancement of water vapour permeability (WVP) and the excellent moisture absorption–desorption cyclist performance illustrated the moisture regulation hypothesis mechanism of DES@Gel. Furthermore, cherry tomato preservation experiment was carried out and the groups treated with DES@Gel showed better performances. The moisture regulation property of DES@Gel could broaden new avenues for active packaging.

The moisture adsorption, caking, and flowability of silkworm pupae peptide powders: The impacts of anticaking agents.

This study aimed to explore the impacts of different anticaking agents on the moisture adsorption, caking, and flowability of silkworm pupae peptide powders (SPPP). The characteristics of water distributions in SPPP with anticaking agents were investigated by LF NMR. The morphological observation of powders was analyzed by scanning electron microscope. Moisture sorption curves and moisture sorption isotherm curves indicated that calcium stearate, silicon dioxide and calcium silicate of 20% reduced hygroscopicity and increased critical relative humidity. The angle of repose analysis revealed that anticaking agents could also increase flowability (45°-49°). LF NMR analysis indicated that anticaking agents reduced the moisture adsorption ability of SPPP. Scanning electron microscope observations demonstrated different shapes and surface morphology of SPPP using different anticaking agents. Notably, silicon dioxide served as the most effective anticaking agent by forming a physical barrier. Overall, anticaking agents can effectively delay moisture adsorption and deliquescence of SPPP by different anticaking fashions.

End-to-end differentiability and tensor processing unit computing to accelerate materials’ inverse design

Numerical simulations have revolutionized material design. However, although simulations excel at mapping an input material to its output property, their direct application to inverse design has traditionally been limited by their high computing cost and lack of differentiability. Here, taking the example of the inverse design of a porous matrix featuring targeted sorption isotherm, we introduce a computational inverse design framework that addresses these challenges, by programming differentiable simulation on TensorFlow platform that leverages automated end-to-end differentiation. Thanks to its differentiability, the simulation is used to directly train a deep generative model, which outputs an optimal porous matrix based on an arbitrary input sorption isotherm curve. Importantly, this inverse design pipeline leverages the power of tensor processing units (TPU)—an emerging family of dedicated chips, which, although they are specialized in deep learning, are flexible enough for intensive scientific simulations. This approach holds promise to accelerate inverse materials design.

Equilibrium Moisture Sorption Isotherms of Aspirin

Equilibrium Moisture sorption isotherms are very important in drying and storage analysis. Experimental moisture equilibrium data (adsorption and desorption) of Aspirin were determined using the static method of saturated salt solutions and that by exposing the material to different conditions of temperatures and water activities. Three different temperatures (25, 30, 40Cº) and water activities in the range of (6.3- 83.6%) were used. The results showed that the equilibrium moisture content increased with the increase in water activity at any temperature and decreased with temperature increase at constant water activity. The water activity increases with increasing in temperature when moisture content was kept constant. The sorption isotherm curves are of type II according to Brunauer`s classification. The hysteresis effect was not distinctly expressed only for equilibrium sorption values of Aspirin at 25ºC. The experimental results were fitted to two sorption models (GAB and Henderson).The average relative deviation between the experimental and calculated data were obtained to select the best model. The GAB and Henderson models, obtaining values of 3.54 and 1.42 % average relative deviation and coefficient of regression of 0.98 and 0.977 respectively. The Henderson model was found to be the best fit out of the two models to predict the sorption behavior of Aspirin.

Water Sorption Isotherm of Ebi Seasoned Potato Chip Model

The aim of this study was to determine the characteristics of the water sorption isotherm of dried shrimp (ebi) seasoned potato chips (ESPC) model and the appropriate equation model. The parameters used were critical parameters for quality degradation such as water content (%), crispness value (hardness force) and hedonic organoleptic analysis. ESPC samples were stored at room temperature, with different humidity conditions, namely 100%, 84%, 75.5%, 43%, 32.4% and 6.90% using water and saturated solution of KCl, NaCl, K2CO3, MgCl2 and NaOH respectively until reaching constant weight. During storage, the samples were analysed its water content, hardness force values and texture hedonic scores. The critical moisture content and critical texture of ESPC is 5.82% and 4.45N, i.e., when the the texture hedonic scores at least 4.0. The Water Sorption Isotherm curve of ESPC was examined with equation models of Hasley, Chen-Clayton, Henderson, Caurie and Oswin. The fittest model is determined by using Mean Relative Determination (MRD) of which the lowest value of the obtained MRD to be considered as the best model. This study revealed that best equation model for describing the water sorption isotherm of ESPC model was the Oswin equation model.

Understanding surface complexation of antimony on Mg(OH)2: Insights from first-principles molecular dynamics

Sorption processes at the mineral–water interface are of great importance in dominating the fate and availability of metalloid contaminants in natural environment. Aiming at a thorough understanding of the complexation of antimony (Sb) on metal hydroxide, we conducted first-principles molecular dynamic (FPMD) simulations and batch adsorption experiments to elucidate the quantitative mechanism of Sb complexation on Mg(OH)2. Batch experiments showed the sorption of Sb(III) is nearly pH-independent, while increasing pH markedly weakened Sb(V) sorption; the measured sorption isotherm curves were well fitted by Langmuir model. Subsequently, molecular-level mechanism of Sb(V)/Sb(III) on brucite basal and edge surfaces were revealed by FPMD, including microscopic surface reactive sites, local complexing structures and coordination geometries, and complexing free energies. Results showed that Sb(III)/Sb(V) can form outer-sphere complexation on basal surface by hydrogen bonding. On edge surface, Sb(III)/Sb(V) formed stable inner-sphere mononuclear monodentate and binuclear bidentate complexes. The calculated free energies indicated that the binuclear bidentate complexing was more favorable than monodentate structure, and the complexation of Sb(III) was more stable than Sb(V). Accordingly, reaction pathway of the ligand exchange and thermodynamic stability of the different inner-sphere complexes were clarified. This study provides theoretical basis for evaluating the environmental risk of Sb and improving the engineering efficiency of Sb-contaminated water management.

Shelf life evaluation of formulated cookies from Hanjeli (Coix lacryma-jobi L.) and Moringa leaf flour (Moringa oleifera)

Hanjeli (Coix lacryma-jobi L.) and moringa leaf (Moringa oleifera) remain underutilised despite their high nutritional value for food. In the present research, cookies made from hanjeli (Coix lacryma-jobi L.) with moringa leaf flour (Moringa oleifera) have been developed. Hanjeli cookies were measured for nutritional composition and shelf life assessment. The shelf life evaluation of hanjeli-moringa cookies was calculated using two approaches, which were accelerated shelf life testing (ASLT) methods with critical moisture content and the Arrhenius method. The results of the nutritional composition analysis showed that hanjeli-moringa cookies contain protein (9.14%), fat (24.67%), carbohydrates (61.62%), crude fibre (4.85%), and energy (505.01 Kcal). Using the Arrhenius method, the shelf life of hanjeli-moringa cookies was 95.46 days at room temperature and 97.63 days at 20 °C. Meanwhile, the shelf life of cookies using the critical moisture content approach was 170.57 days. Shelf life is influenced by initial moisture content, critical water content of the product, packaging surface area and permeability, saturated vapour pressure, and slope sorption isotherm curve. The formulated cookies have significant amounts of nutrients that are acceptable and safe for consumption, with guaranteed desirable sensory properties. The result of this study shows that hanjeli-moringa cookies can be used as an alternative food for people who need high energy in a practical way of serving or ready to eat.

Shelf-life Estimation of Mocaf Dry Noodles Using Critical Moisture Content Approach in Various Packaging

This study aims to determine the critical moisture content, moisture sorption isotherm (MSI) curve and the shelf-life of mocaf dry noodles products using the Accelerated Shelf-Life Testing (ASLT) approach to the critical moisture content approach using two types of packaging, PP (Polypropylene) and metalized. The results of this study are obtained critical moisture content of mocaf dry noodles products of 15.8467% (db), with the MSI curve at 30°C forming a type II isotherm type sigmoid curve with the equation y = 202.79x3-2261x2 + 110.36x2, 4188 with R2 = 0.9846. Calculation results for estimating the shelf-life of mocaf dry noodles are 992.739 days with PP (Polypropylene) packaging and 2,171.831 days with metalized packaging.

Experimental Determination and Modeling of the Moisture-Sorption Isotherms and Isosteric Heat of Tobacco Leaves

During a forced convection sun drying and storage operation, the equilibrium water content of a product to be dried is critical. These figures are frequently derived using isothermal sorption curves. The calculation of isotherms is a necessary step in determining the distribution and intensity of water connections in products. for that this paper concentrates on the experimental determination of the adsorption-desorption isotherms for various temperatures (40, 50, and 60℃) of the Nicotiana Tabacum L plants. From which we had established the relationship between the water activity and the water content in the product. However, the aforementioned determination was carried out by the static gravimetric method. Eight saturated salt solutions have been utilized in applications such as (KOH, KCl, MgCl2, MgNO3, K2CO3, BaCl2, K2SO4, and NaCl). Hygroscopic equilibrium was completed after 13 days for temperature 40℃, 11 days for 50℃, and 9 days for 60℃. The overall experimental sorption curves are summarized by six models (HENDERSON, modified HALSEY, OSWIN, GAB, modified BET, and PELEG). The sorption isotherms built using the Clausius–Clapeyron equation were used to determine the net isosteric temperatures of desorption and adsorption of Nicotiana Tabacum L. The results for the adsorption-desorption isotherms found are type III according to IUAPC. Following the smoothing of the experimental results by different used models, it was found that the models of GAB and Peleg allow having the lowest mean relative errors and correlation coefficient.

Effects of pretreatment and air drying temperature on Noni fruit powder.

The plant Morinda citrifolia L. (Noni) has been the subject of several recent research due to its positive impact on the treatment and prevention of a variety of diseases. Noni fruits contain a variety of phytochemicals, including flavonoid, polyphenol, and triterpenoid saponin. This study aimed to determine the best pre-treatment (including blanching, soaking in ascorbic acid solution and metabisulfite solution) and air-drying temperature (50, 60, 70, and 80°C) to maximize the total polyphenol content (TPC), flavonoid content (TFC), and triterpenoid saponin contents (TSC) of the resultant Noni fruit powder. The results revealed that pre-soaked Noni fruit samples in ascorbic acid or metabisulfite solution before air-drying at 60°C were beneficial in preserving TPC, TFC, and TSC. TPC, TFC, and TSC losses increased as drying temperatures (70 and 80°C) rose. The optimum sample was held at five different relative humidity conditions until they attained weight equilibrium. The results indicated that the sorption isotherm curve of the Noni powder was the sigmoid shape and fitted with the BET and GAB models.

The effect of the use of perkamen paper packaging on the shelf life estimation of Bolu Cukke using the Accelerated Shelf LifeTesting (ASLT) method

This study aims to estimate the shelf life of Bolu Cukke packaged in parchment paper using the Accelerated Shelf Life Testing (ASLT) method. The critical water content parameters in Bolu Cukke are its aroma and its texture. The equilibrium moisture content was obtained from six types of saturated salt solution in the humidity chamber with 7-84% RH. Isothermal sorption curves are obtained by plotting Aw with equilibrium moisture content (Me) which would be tested using five isothermal sorption equation designs to obtain the Mean Relative Deviation (MRD) value. The lowest MRD value is 9.2 obtained from Hasley’s Isothermal equation design. All variables were then collected using the Labuza equation. The results of this study indicated that the estimation of shelf life of Bolu Cukke products in the parchment paper packaging at 30°C with 78% RH is approximately 7 days.

Shelf-life assessment of energy banana bar using acceleration method with critical moisture content approach

The shelf-life of the product need to be evaluated according to the commercialization of the product. Shelf-life assessment of the product can be done using acceleration method (Accelerated Shelf-life Testing) with critical moisture content approach. This research used the acceleration method to predict the expired date of the energy bar based banana. This method required the data such as initial water content, critical moisture content, solid weight of the product, surface area of the packaging, permeability water vapor of the packaging, saturated water vapor pressure, and slope of the sorption isotherm curve. The result showed that the shelf life of banana bar products that was packaged using aluminium foil, aluma, and metalized plastics consecutively for 511.15; 458.72; and 80.95 days based on the acceleration method with the critical moisture content approach.

Effect of Emulsifier Diacetyl Tartaric Acid Ester of Mono- and Diglycerides (DATEM) and Enzyme Transglutaminase on Quality Characteristics of Rice Bran Croissants

Rice bran (RB) is a good source of dietary fibre. Addition of rice bran into croissant interferes with the gluten formation of dough and hence affect the physicochemical properties of croissant. The effect of RB addition on physicochemical properties of croissant were determined by using 0%, 10% and 15% RB. Besides, additives such as emulsifiers and enzymes can be used in pastry to enhance the physicochemical properties of croissant. Diacetyl tartaric acid ester of mono-diglycerides (DATEM) and transglutaminase (TGase) were used respectively on 0%, 10% and 15% RB to investigate the effect of such additives on physicochemical properties of croissant. Increased % RB and DATEM, produced a significant decrease in specific volume, together with a significant increase in colour, hardness and chewiness. With increased % RB, TGase caused significant increase in colour, hardness and chewiness but significant decrease in specic volume. The overall moisture sorption isotherm curves of the croissant belong to the Type III isotherm, also known as Flory-Huggins Isotherm (J-shaped). The critical aw obtained from the Guggenheim-Anderson-de Boer (GAB) equation showed that the shelf life of croissants were not positively impacted by the addition of DATEM and TGase and the addition of RB did not cause any significant positive effects on quality characteristics of croissants.

More reasons to add less salt – NaCl's unfavourable impact on glass transition and moisture sorption of amorphous maltose-NaCl blends

Adding NaCl to maltose depressed the glass transition temperature (T g ) of freeze-dried maltose-(dissociated) NaCl powder (by up to 9.1 °C at 10%mol addition level) but did not impact sorption isotherm in the water activity (a w ) range of 0.1–0.3. Above 2%mol NaCl, moisture and NaCl had an antagonistic effect on T g depression of freeze-dried maltose-NaCl powder. According to linear and Flory-Fox models, T g increased linearly with mixtures’ molecular weight. T g and sorption isotherm curves were then combined to determine the a w at which glass transition occurs at various storage temperatures (i.e. critical a w ). From the combined curve, critical a w decreased linearly with increased NaCl concentration in the mixture. Furthermore, the critical a w depression was steeper at higher temperatures. Finally, neither processing (dry mixing versus freeze drying) nor NaCl concentration affected the crystallization kinetics of amorphous maltose during dynamic humidification (0 to over 90% relative humidity) at 25 °C. • NaCl lowered the temperature and humidity at which amorphous maltose becomes sticky. • Temperature sensitivity can be predicted by amorphous mixtures' molecular weight. • Adding ≤10%mol NaCl did not affect amorphous maltose's crystallization kinetics.

Isothermal adsorption modelling of pupuru flour

The amount of moisture adsorbed by stored food products usually varies with temperature and relative humidity at a constant pressure. This research was carried out to determine the sorption isotherm behaviour of pupuru flour in the temperature and water activity (aw) ranges of 10−50 oC and 0.10−0.93 using gravimetric method. The Guggenheim-Anderson-De Boer (GAB), Brunauer-Emmett-Teller (BET), Oswin and Smith sorption equations, formulated for the sorption characterization of starchy foods, were used to constitute the models. The results show that the sorption isotherm curve is similar to a Type II classification typical of starchy foods. Also, the sorption parameters (Mo, C and K) were generally higher for the products stored at 10 oC and 0.10 aw. The parameter K decreases with an increase in the temperature for the GAB and the Smith models, but remains inconsistent for the Oswin model. The Mo increases with an increase in the temperature for the GAB and Smith models. The GAB, Oswin and Smith models were generally adequate and valid with an MSE< 10% and a high degree of fitness (R2 and R2adj > 90%). This indicates their ability to predict the sorption isortherm characteristics of the pupuru flour within its range of the aw and the storage temperature.

In situ study of the temperature activated kinetics of water sorption in an epoxy varnish

The dielectric permittivity of a polyepoxy varnish with a glass transition temperature (Tg) of 61 °C is monitored during immersion in a 0.5 M NaCl aqueous solution, by electrochemical impedance spectroscopy, at various temperatures in the range [21; 78] °C. The sorption curves are first analysed with a Fickian approach. An Arrhenius-type dependence of the apparent coefficient of diffusion is observed, with no visible influence of Tg. Below 46 °C, the sorption curves clearly do not obey Fick′s second law of diffusion. On another hand, the Kohlrausch-Williams-Watts function (KWW) satisfactorily fits all the isothermal sorption curves. The KWW time constant has the same temperature activation as the apparent coefficient of diffusion, and likewise is unaffected by Tg. The KWW stretching exponent displays a strong dependence on Tg, correlates with the Fickian behaviour observed in the rubbery state, and is thought to be governed by molecular heterogeneities in the polyepoxy network. A linear rule of mixture is used to estimate the water uptake in the polyepoxy varnish as a function of temperature. The originality of this work lies in the in situ analysis of water uptake kinetics (constant immersion), which is performed above (rubbery state) and below (glassy state) the Tg of the polyepoxy coating.