Moisture Diffusion Coefficient Research Articles

Development of an Apple Snack Enriched with Probiotic Lacticaseibacillus rhamnosus: Evaluation of the Refractance Window Drying Process on Cell Viability.

The objective of this study was to develop a dried apple snack enriched with probiotics, evaluate its viability using Refractance Window (RWTM) drying, and compare it with conventional hot air drying (CD) and freeze-drying (FD). Apple slices were impregnated with Lacticaseibacillus rhamnosus and dried at 45 °C using RWTM and CD and FD. Total polyphenol content (TPC), color (∆E*), texture, and viable cell count were measured, and samples were stored for 28 days at 4 °C. Vacuum impregnation allowed for a probiotic inoculation of 8.53 log CFU/gdb. Retention values of 6.30, 6.67, and 7.20 log CFU/gdb were observed for CD, RWTM, and FD, respectively; the population in CD, RWTM remained while FD showed a decrease of one order of magnitude during storage. Comparing RWTM with FD, ∆E* was not significantly different (p < 0.05) and RWTM presented lower hardness values and higher crispness than FD, but the RWTM-dried apple slices had the highest TPC retention (41.3%). Microstructural analysis showed that RWTM produced a smoother surface, facilitating uniform moisture diffusion and lower mass transfer resistance. The effective moisture diffusion coefficient was higher in RWTM than in CD, resulting in shorter drying times. As a consequence, RWTM produced dried apple snacks enriched with probiotics, with color and TPC retention comparable to FD.

Moisture migration mechanism of round bamboo in the radial direction during drying

Round bamboo exhibits a hierarchical gradient wall structure and contains closed bamboo cavities, creating a complex pathway for radial moisture migration. In this project work, round bamboo was dried at different temperatures (60, 75 and 90 °C), and the radial moisture content distribution and moisture migration pathway in the drying process were elucidated using the X-ray method, micromorphology and theoretical calculations. The porosity and average aperture of the inner bamboo internode were 38.92 % and 14.98 nm respectively, which were higher than those of the outer (23.17 % and 13.83 nm). The moisture diffusion coefficient at the bamboo diaphragm was about 1/4 that of the bamboo internode. The radial moisture content distribution in fresh round bamboo exhibited an asymmetric distribution, with higher levels in the middle and lower levels on both sides. During the drying process, moisture primarily migrated through the outer surface under the moisture gradient, with a small amount entering the bamboo cavity through the inner surface by temperature action. The moisture entering the bamboo cavity eventually migrated slowly through the diaphragm.

Drying Kinetics and Energy Consumption of Astragalus Membranaceus Under Infrared Drying

Abstract The Astragalus membranaceus (AM) slices was dried using three infrared drying techniques, including near-infrared drying (NIR), mid-infrared drying (MIR), and far-infrared drying (FIR). Studies and discussions about the impacts of infrared temperature, power, slice thickness, and wavelength on the drying properties, energy consumption, and associated performance were conducted. Results showed that the drying rate increased with increasing infrared temperature and wavelength, and with decreasing slice thickness, whereas the drying process was not significantly influenced by the infrared power. The drying efficiency of FIR was superior to that of NIR, and with the increase in temperature, this improvement became more obvious. FIR drying was the fastest with the least energy consumption among the three drying methods. Rehydration ratio and color change of AM slices were proportional to infrared temperature and wavelength, but inversely proportional to slice thickness. The effective moisture diffusion coefficients of AM slices under NIR and FIR drying ranged from 0.49244 × 10−9 to 1.16352 × 10−9 m2/s and 1.00432 × 10−9 to 2.51135 × 10−9 m2/s, respectively.

Instant controlled pressure drop (DIC) as an effective pretreatment to intensify drying efficiency and enhance quality attributes of heat pump dried scallop adductors

Scallop adductors (SA) with a moisture content (MC) of 65% (H-65), 55% (H-55), 45% (H-45), and 35% (H-35) were subjected to an instant controlled pressure drop (DIC) pretreatment to investigate its influence on the subsequent heat pump drying kinetics and quality attributes. SA without DIC was performed for comparison (CK). Compared to the CK, DIC resulted in a decreasing rate of 5.88–35.29% in the drying time, but an increasing rate of 11.12–46.89% in effective moisture diffusivity coefficient depending on samples' MC. After DIC, SA showed a decrease in α-helices and β-turns, but an increase in β-sheets, and a sharp decrease in the relaxation time and proportion of the immobilized water. DIC increased total color difference (expect H-45), hardness, rehydration ratio, but decreased shrinkage rate (except H-65) compared to the CK. DIC is a promising pretreatment for intensifying drying efficiency, inhibiting volume shrinkage, and improving rehydration capacity of SA.

Drying kinetic, thermodynamic and quality analyses of infrared drying of truffle slices.

Kinetic and thermodynamic parameters are the most important part for making a suitable tool for drying agricultural products. Moreover, calculation of the energy required for the drying of product, the properties of the rehydration ratio, the food appearance changes, and the evaluation of the microstructure of food are crucial. Since the thermodynamic properties of truffle slices have not yet been reported, this study aims to establish a mathematical model to describe drying process of agriculture product, evaluate the effective moisture diffusion coefficient (Deff), determining the activation energy (Ea) to elucidate the thermodynamic characteristics, measure color characteristics, and rehydration ratio (RR) during the drying process of truffle slices. Truffle slices were dried in an infrared (IR) dryer at four temperatures of 50-80°C and two thicknesses of 0.5 and 1cm. The best model to describe the drying process of truffle slices was Midilli etal.'s model. The value of Deff, SEC, and RR were in the range of 3.06 × 10-8 to 2.48 × 10-7 m2/s, 79.68-191.271kWh/kg, and 5.99-7.49, respectively. The Deff of truffle slices increased with the above-mentioned parameters of the samples. The Ea obtained was 26.62-27.43kJ/mol. The results indicated that enthalpy and entropy decreased with increasing drying temperature, while Gibbs free energy improved. The enthalpy, entropy, and Gibbs free energy values changed between 24.48-25.28kJ/mol, -130.47 to -122.63 J/mol °K, and 63.97-70.17kJ/mol, respectively. In addition, the results of color attributes decreased with increasing temperature, while chroma oppositely increased.

Combined refractance window and far infrared radiation drying of Spirulina platensis biomass: Drying behavior, moisture and thermal diffusivity, and biochemical characterization

A 2 mm thin layer of wet Spirulina platensis biomass was dried using two methods: refractance window drying (RW) and combined RW and FIR drying (RWF). The effect of drying temperature (40–60 °C) and proximity to FIR heaters (5 and 10 cm) was evaluated on falling rate drying characteristics. The moisture (Deff) and thermal (α) diffusivity coefficients were obtained in the range 1.728 × 10−8 to 5.289 × 10−9 and 1.322 × 10−8 to 4.169 × 10−9 m2 s−1, respectively (R 2, 0.921–0.984). RW drying at ≥50 °C caused loss of color, phytopigments, and lipid peroxidation. At 40 °C, RW drying led to a long drying period (300.50 ± 3.53 min), poor drying rate (0.039 ± 0.002 g-H2O/min), lowest Deff and α (5.289 × 10−9 and 4.169 × 10−9 m2 s−1), and chlorophyll loss (32.2%). Combined RW and FIR drying at 40 °C and 5 cm proximity (RWF40-5cm) reduced drying time (15.1%), increased drying rate (27.8%), improved α (15%), and Deff (14.9%). RWF40-5cm dried biomass showed excellent retention of color (ΔE = 4.64 ± 1.32), protein (93.8%), γ-linolenic acid (90.1%), chlorophyll (87.9%), and phycocyanin (86.7%) from freeze-dried biomass (FD). Low-temperature RWF40-5cm drying could be a potential alternative to freeze-drying for effective and safe drying of heat-sensitive Spirulina platensis biomass.

The Mathematical Modeling, Diffusivity, Energy, and Enviro-Economic Analysis (MD3E) of an Automatic Solar Dryer for Drying Date Fruits

Date fruit drying is a process that consumes a significant amount of energy due to the long duration required for drying. To better understand how moisture flows through the fruit during drying and to speed up this process, drying studies must be conducted in conjunction with mathematical modeling, energy analysis, and environmental economic analysis. In this study, twelve thin-layer mathematical models were designed utilizing experimental data for three different date fruit varieties (Sakkoti, Malkabii, and Gondaila) and two solar drying systems (automated solar dryer and open-air dryer). These models were then validated using statistical analysis. The drying period for the date fruit varieties varied between 9 and 10 days for the automated solar dryer and 14 to 15 days for open-air drying. The moisture diffusivity coefficient values, determined using Fick’s second law of diffusion model, ranged from 7.14 × 10−12 m2/s to 2.17 × 10−11 m2/s. Among the twelve thin-layer mathematical models, we chose the best thin drying model based on a higher R2 and lower χ2 and RMSE. The Two-term and Modified Page III models delivered the best moisture ratio projections for date fruit dried in an open-air dryer. For date fruit dried in an automated solar dryer, the Two-term Exponential, Newton (Lewis), Approximation diffusion or Diffusion Method, and Two-term Exponential modeling provided the best moisture ratio projections. The energy and environmental study found that the particular amount of energy used varied from 17.936 to 22.746 kWh/kg, the energy payback time was 7.54 to 7.71 years, and the net CO2 mitigation throughout the lifespan ranged from 8.55 to 8.80 tons. Furthermore, economic research showed that the automated solar dryer’s payback period would be 2.476 years.

Changes of Temperature and Moisture Distribution over Time by Thermo-Hydro-Chemical (T-H-C)-Coupled Analysis in Buffer Material Focusing on Montmorillonite Content

Bentonite is used as a buffer material in engineered barriers for the geological disposal of high-level radioactive waste. The buffer material will be made of bentonite, a natural clay, mixed with silica sand. The buffer material is affected by decay heat from high-level radioactive waste, infiltration of groundwater, and swelling of the buffer material. The analysis of these factors requires coupled analysis of heat transfer, moisture transfer, and groundwater chemistry. The purpose of this study is to develop a model to evaluate bentonite types and silica sand content in a unified manner for thermo-hydro-chemical (T-H-C)-coupled analysis in buffer materials. We focused on the content of the clay mineral montmorillonite, which is the main component of bentonite, and developed a model to derive the moisture diffusion coefficient of liquid water and water vapor based on Philip and de Vries, and Kozeny–Carman. The evolutions of the temperature and moisture distribution in the buffer material were analyzed, and the validity of each distribution was confirmed by comparison with the measured data obtained from an in situ experiment at 350 m in depth at the Horonobe Underground Research Center, Hokkaido, Japan.

Study on heat and moisture transfer of nonspherical rice during hot‐air drying in thin‐layer grain pile

AbstractTo investigate fluid flow and coupled heat‐moisture transfer in the hot‐air drying of grain piles, this study integrated the discrete‐element method with computational fluid dynamics. A model for a thin‐layer grain pile, consisting of nonspherical rice particles represented by 13 spheres, was developed. Using a heat‐moisture transfer model based on fluid–solid coupling, the drying process with hot air was simulated and validated against experimental data. Finally, by controlling the drying temperature and the initial moisture content of rice, the variations in temperature and moisture content during the hot‐air drying process were explored. The numerical results indicated that the nonuniform pore structure within the grain pile, gaps on the surface of nonspherical rice, and the wall effect led to complex airflow patterns, resulting in the formation of dead zones within the grain pile. The oscillation frequency and amplitude of radial porosity near the wall were relatively large, and the minimum porosity occurred at a radial distance of 1/2dg. Heat and moisture transfer rates between the rice and drying air were influenced by the temperature and moisture concentration differences. During the drying process, variations in temperature and moisture content were observed among rice particles. Limited by the moisture diffusion coefficient, there existed a notable disparity in moisture content between the interior and surface of the rice. The results also showed that the curvature of the drying curve in the grain pile varied and was influenced by the drying conditions, especially under the high‐temperature drying condition of 60°C.Practical ApplicationsIn this study, a grain pile model for nonspherical rice particles composed of 13 spheres was developed based on the discrete‐element method and computational fluid dynamics. Furthermore, in accordance with the heat and mass transfer mechanism of fluid–solid coupling, a heat‐moisture transfer model for the hot‐air drying of the grain pile was constructed. This was done to deeply explore the internal fluid dynamic characteristics and the heat‐moisture transfer within the grain pile during the drying process. The newly established model can be widely applied to numerical simulation studies of drying and also has reference value for the design of drying systems.

Evaluation of three suction pretreatment systems for the air compressor

Air compressor, as the power source of pneumatic tools, suffers the problems of low efficiency and high failure rate in summer. In this paper, three suction air pretreatment systems are presented, which are characterized by the cold sources: a vapor compression refrigeration unit, a water chilling unit and a combination of water chilling unit with cooling tower. Models for the thermodynamic and economic performance evaluation of the three systems are established and solved. The moisture diffusion coefficient is applied to consider the influence of the moisture condensation and the Marshall and Swift coefficients is introduced to consider the capital change over time. Formula to calculate the efficiency of refrigeration compressor is adopted. Besides, the system total efficiency, percentage of power saving (PPS) and payback period (PBP) are defined as performance indexes. A comparative study with typical meteorological data of hot-dry regions and hot-humid regions is conducted to analyze the superiority of each system under the operation conditions of varied suction air temperature and volume flow. According to the results, optimal spray water flowrate exists for each operation condition and an air–water ratio of 0.8 is recommended. When the suction air temperature decreases, the PBP of each system increases and a sharp increase occurs when the temperature is lower than the air dew point temperature. A suction air temperature of 26 ℃ is suggested. Direct air cooling with an evaporator is preferred when the suction air volume flowrate is smaller than 60 m3/min for hot-humidity regions. The combined system is significantly superior in hot-dry regions. The PBP of the three systems is all longer than 10 months. How to guarantee the usage rate is the key for enterprises to consider the use of suction air pretreatment systems.

Influences of hygrothermal conditions and structure parameters on moisture diffusion behavior in a system‐in‐package module by moisture-thermal-mechanical-coupled finite element modeling

Purpose This paper aims to investigate the moisture diffusion behavior in a system-in-package module systematically by moisture-thermalmechanical-coupled finite element modeling with different structure parameters under increasingly harsh environment. Design/methodology/approach A finite element model for a system-in-package module was built with moisture-thermal-mechanical-coupled effects to study the subsequences of hygrothermal conditions. Findings It was found in this paper that the moisture diffusion path was mainly dominated by hygrothermal conditions, though structure parameters can affect the moisture distribution. At lower temperatures (30°C~85°C), the direction of moisture diffusion was from the periphery to the center of the module, which was commonly found in simulations and literatures. However, at relatively higher temperatures (125°C~220°C), the diffusion was from printed circuit board (PCB) to EMC due to the concentration gradient from PCB to EMC across the EMC/PCB interface. It was also found that there exists a critical thickness for EMC and PCB during the moisture diffusion. When the thickness of EMC or PCB increased to a certain value, the diffusion of moisture reached a stable state, and the concentration on the die surface in the packaging module hardly changed. A quantified correlation between the moisture diffusion coefficient and the critical thickness was then proposed for structure parameter optimization in the design of system-in-package module. Originality/value The different moisture diffusion behaviors at low and high temperatures have seldom been reported before. This work can facilitate the understanding of moisture diffusion within a package and offer some methods about minimizing its effect by design optimization.

Effects of hot air drying on drying kinetics, quality and flavor changes of Fructus aurantii

This study aimed to evaluate the effect of hot air drying on drying kinetics, quality and flavor changes of Fructus aurantii. The results showed that Midilli model (R 2 = 0.9995, RMSE = 6.16 × 10−9, χ 2 = 7.62 × 10−5) was the best model for hot air drying of Fructus aurantii, and the effective moisture diffusion coefficient (D eff) and activation energy (Ea) of hot air drying process was 2.63 × 10−5 - 6.61 × 10−4 m2/s and 42.36 KJ/moL, respectively. The HS-GC-MS and E-nose techniques were used to evaluate the changes in volatile components and aromatic characteristics. The results of HS-GC-MS showed that linalool content was 6.69%, 5.32% and 5.10% at 50°C, 60°C and 70°C respectively, showing a decreasing trend. Flavor radar fingerprint map showed that sensors S13, S12 and S2 have obviously higher response values, S11 , S5, S4 and S9 have higher response values, but other sensors have no obvious response values. PCA analysis showed that the first principal component (PC1) and the second principal component (PC2) accounted for 57.38% and 22.59% respectively, and the cumulative variance contribution rate was 87.1% (> 85%). The results of flavor radar fingerprint and PCA showed that the drying process obviously changed the aroma characteristics. The overall results showed that hot air drying at 50-60°C could effectively improve the final quality of dried Fructus Aurantii by maintaining flavor characteristics.

Drying characteristics and thin layer drying model of semi-mature rice paper

Abstract The effects of different hot air speeds and temperatures on the drying characteristics of half-ripe rice paper were investigated by hot air convection drying experiments. The thin-layer drying experiments were carried out at three different combinations of air speeds of 1.97 m/s, 3.00 m/s, and 3.90 m/s and temperatures of 85 °C, 100 °C and 115 °C. The results show that among the 10 drying kinetic models selected, the Modified Page model is the most suitable model to describe the drying characteristics of the thin layer of half-ripe rice paper; the whole drying process exists obvious ascending, constant and descending processes; the effective moisture diffusion coefficient of half-ripe rice paper is in the range of 1.52656 × 10−9 m2/s–3.15816 × 10−9 m2/s, whose size increases with the increase of the hot wind speed and temperature. Its magnitude increases with the increase of wind speed and temperature; the drying activation energy of half-ripe rice paper is 6.55 kJ/mol calculated by Arrhenius equation.

Study on Drying of Seaweeds and Importance of Glass Transition and Stabilization

In this study, the thermal transition of seaweed Saccharina latissima (raw and blanched) during drying and quality stabilization was considered in view of understanding physico-chemical changes, color changes, sorption changes and thermal property changes with respect to drying kinetics. The variations in the effective moisture diffusivity coefficient with shrinkage changes and temperature lie between 1.0 and 5.0 × 10−10 m2 s−1 (raw) and 0.5 and 3.6 × 10−10 m2 s−1 (blanched), respectively. Noticeable physical and chemical changes were observed during longer drying times, especially in the case of blanched seaweeds. At the temperature of 38.0 °C, a more yellow-colored product was obtained from raw form input materials. The blanched seaweeds accumulated moisture in a linear manner with an increase in the relative humidity of the drying air in the range of 20.0~80.0%, which resulted in high level of hysteresis between the sorption and desorption behavior. Shrinkage changes during the drying of blanched and raw samples were also calculated. The thermal stabilization of raw and blanched forms started at different initial moisture contents showed changed glass transition phenomena during a wide range of temperature sand one melting endotherm between 141.9 and 167.9 °C. Some glass transitions were driven by the presence of water-soluble contents in the material. The dried seaweeds at low temperatures showed a partial glassy state and an amorphous/crystalline state. This study evaluated the effects of process parameters on the properties of dried product.

Determining the effective diffusivity coefficient and activation energy in thin-layer drying of Haj Kazemi peach slices and modeling drying kinetics using ANFIS

Abstract This study investigated the moisture changes in Haj Kazemi peach slices during drying in a thin-layer dryer at five temperature levels (40, 50, 60, 70, and 80°C), three levels of inlet air velocity (1, 1.5, and 2 m/s), and three slice thicknesses (2, 4, and 6 mm). The relative moisture content during drying was calculated, and an adaptive neuro fuzzy inference system (ANFIS) was used to predict the drying process of peach slices. The results indicated that slice thickness had a greater impact on drying time than air velocity. Moreover, an almost direct relationship was observed between changes in slice thickness and drying time. The effective moisture diffusivity coefficient in peach slices increased with an increase in slice thickness, temperature, and air velocity and ranged from 9.57 × 10^-10 to 4.33 × 10^-9 m^2/s under different experimental conditions. The calculated activation energy for drying peach slices under experimental conditions ranged from 16.74 to 20.48 kJ/mol. The designed model for simulating the drying conditions was based on an adaptive neuro fuzzy inference system (ANFIS) with input and output membership functions of triangular and linear shapes and a hybrid learning algorithm. The model could simulate the drying process with a correlation coefficient of 0.979.

Drying Kinetics and Mass Transfer Characteristics of Walnut under Hot Air Drying

This study was conducted to investigate the drying kinetics and internal and external mass transfer characteristics of walnuts for an understanding of the drying mechanism. The drying characteristics, mass transfer characteristics, and color of walnut during hot air drying (HAD) were investigated under different initial moisture content (IMC) (0.35, 0.39, and 0.43 g water/g wet mass) and drying temperatures (50, 60, 70, and 80 °C). The results indicated that the IMC and drying temperature both have significant effects on the drying process of walnut, showing the higher the IMC, the longer the preheating time, the smaller the effective moisture diffusivity (Deff) and mass transfer coefficient (hm), and the longer the drying time, but reverse results for drying temperature. The values of Deff and hm for walnut ranged from 4.94 × 10−10 to 1.44 × 10−9 m2/s and 1.24 × 10−7 to 3.90 × 10−7 m/s, respectively. The values of activation energy for moisture diffusion and mass transfer ranged from 21.56 to 23.35 kJ/mol and 28.92 to 33.43 kJ/mol, respectively. Multivariate linear prediction models were also established for estimating the Deff and hm as a function of the HAD process parameters. The drying temperature has a greater effect on the walnut kernel lightness than the IMC. The Verma et al model could be used to describe the HAD process of the walnut. The findings contribute to the understanding of moisture transfer mechanisms in walnuts and have practical value for the evaluation and improvement of drying systems.

Effect of ultrasound-ethanol immersion, microwave and starch-blanching pretreatments on drying kinetics, rehydration, and quality properties of beetroot chips

Abstract For the first time, the impact of ultrasound-ethanol immersion as a non-thermal pretreatment (NTPT) and coating-blanching in starch solutions as a thermal pretreatment (TP) on the convective drying of beetroot was evaluated. The beetroot was exposed to ethanol immersion (E), ultrasound (U), and ultrasound-ethanol immersion (UE). Besides, TP pretreatment was performed by blanching the beetroot at steam (SB), water (WB), starch-coating solutions, and microwave (M). The hot air drying was conducted at 90 °C and air velocity of 1.2 m/s. The maximum decreases in the drying time were observed at UE30 (64.29 %) and the sample blanched at native corn starch solution (60.17 %). Moisture diffusion coefficients ranged from 0.851 to 2.312 × 10−9 m2/s. The friction drag force, convective heat, and mass transfer coefficients were 2.840 × 10−6 N, 59.368 W/m2 K, and 0.0492 m/s, respectively. The thermal conductivity, specific heat, and density ranged from 0.464 to 0.615 W/m. K, 3164–4071 J/kg. K, and 798.9 to 1055.9 kg/m3, respectively. The maximum values of rehydration ratio at non-thermal (NTPT) and thermal pretreatments (TP) were observed at U30 and the sample blanched at the modified starch solution (MCS), respectively. The total phenolic contents of the NTP sample decreased while those for the TP samples increased due to boosted polyphenol synthesis at high temperatures. Both U and E samples caused a decrease in the total antioxidant activity, while they increased the anthocyanin content of beetroot samples. Pretreatments reduced the hardness owing to changes in the microstructure of the sample. U, E, and M pretreatments increased the brightness of samples, and the minimum color change compared with control samples was observed by UE30 pretreatment. The UE and blanching at a starch solution could be selected for improving the drying characteristics of beetroots at an industrial scale.

Influence of ultrasound pretreatment on drying characteristics of cocoyam (Xanthosoma sagittifolium) slices during convective hot air drying.

Convective hot air drying of cocoyam is risk-free and inexpensive to a significant level. However, hot air drying causes negative changes to the color, texture, flavor and nutritional content of cocoyam as a result of the prolonged drying. Recently, the innovative technology of ultrasound pretreatment has been applied in food processing to reduce the processing time, conserve energy and preserve the quality of the food product. Thus, there is need to investigate the effect of ultrasound pretreatment with distilled water (UDW) and ultrasound with osmotic dehydration (UOD) for different ultrasonic times (10-30 min) on the drying kinetics of cocoyam slices during convective hot air drying. Ultrasound pretreatment was applied at a frequency of 20 kHz and an output power of 600 W for UDW and UOD. The ultrasound-pretreated samples were further dried in a convective hot-air drying oven at 70 °C. UDW and UOD samples, respectively, had a 25% and 46% reduction in drying time compared to untreated samples. The UOD samples had the lowest activation energy (10.697 kJ), as well as the highest moisture diffusivity (3.782 × 10-10 m2 s-1 ) and mass transfer coefficient (2.006 × 10-8 m s-1 ), among the untreated and UDW samples. Wang and Singh, Page and Peleg models were found to be the most fitted models with respect to the drying characteristics of cocoyam for untreated, UDW and UOD samples, respectively. Ultrasound pretreatment technology is a potential non-thermal process that can be incorporated as a pretreatment method in the convective drying of cocoyam to reduce processing time, conserve energy and enhance cocoyam product shelf life. © 2023 Society of Chemical Industry.

Effect of hygrothermal aging on novel hybrid composites: Transforming textile waste into a valuable product

AbstractThe textile industry now produces thousands of tons of waste worldwide, and the total amount of discarded material waste increases yearly. Hygrothermal aging of cotton/E‐glass (hybrid) fiber reinforced with various proportions of graphene oxide (0%, 1%, 3%, 5%, 7%, and 9%) was performed. Epoxy and vinyl ester (50:50) have been chosen because of the Interpenetrating Polymer Networks (IPNs) concept. Laminates were subjected to 50, 60, and 70°C temperatures for 180 days. Further, Tg and the degree of cross‐linking have been determined by using differential scanning calorimetry (DSC). DSC analysis proves that a hot water bath enhances the cross‐linking of the polymer. IPN laminates were also intermittently weighed for water uptake, and their consecutive mechanical properties like tensile, flexural, and impact strength were obtained. From this work, it was observed that the addition of 5 w.t% graphene oxide in cotton/E glass fiber vinyl ester/epoxy resin hybrid IPN composites showed a tensile strength of 375.61 MPa, flexural strength of 393.54 MPa, Interlaminar shear strength (ILSS) of 49 MPa and the impact strength of 22.54 MPa. Moreover, the lowest inclusion of particulate addition exhibits better mechanical properties than (up to 5% of GO) the highest particulate loading into the matrix. SEM study was conducted on the broken specimens to know the impact of diffusion characteristics on the physical properties of the IPN composites.Highlights Natural and synthetic fibers are used as reinforcements. Waste cotton/E glass fiber vinyl epoxy composites are fabricated. Laminates were subjected to diverse temperatures for 180 days. The moisture diffusion coefficient is proportional to water temperature. Bathtub temperature affects the tensile strength of the laminate.

Effect of Electrohydrodynamic Drying on Drying Characteristics and Physicochemical Properties of Carrot.

This study investigates the effects of electrohydrodynamic (EHD) drying technology on the drying kinetics, microstructure, quality, and nutritional components of carrots, along with conducting experiments on EHD drying under different voltage gradients. The experimental results showed that EHD drying technology could significantly increase the drying rate and the effective moisture diffusion coefficient. Within a certain range, the drying rate was directly proportional to the voltage. When the range was exceeded, the increase in voltage had a minimal effect on the drying rate. In terms of quality, the EHD drying group's color, shrinkage rate, and rehydration performance were superior to the control group, and different voltages had no significant effect on the shrinkage rate and rehydration performance. The retention of carotenoids in the EHD drying group was 1.58 to 2 times that of the control group. EHD drying had a negative impact on the total phenolic content and vitamin A content of dried carrot slices. Based on the results of infrared spectroscopy and scanning electron microscopy (SEM), the dehydrated carrot slices showed wrinkling due to water loss, with numerous pores, a generally intact structure, and retained functional groups. EHD drying had a significant impact on the secondary structure of proteins, where an increase in voltage led to an increase in disordered structure, with a smaller proportion of disordered structure in the lower voltage group compared to the control group, and a similar proportion of disordered structure between the higher voltage group and the control group. Results from low-field nuclear magnetic resonance (NMR) showed that EHD drying could retain more bound water compared to the control group, with the best retention of cellular bound water at a voltage of 26 kV and the best retention of cellular immobilized water at a voltage of 38 kV, indicating the superiority of EHD drying in preserving cellular structure. This study provided a theoretical basis and experimental foundation for the application of electrohydrodynamic drying technology to carrot drying, and promoted the practical application of EHD drying technology.