Rheological Properties Research Articles

Rheological properties and 3D printability of tomato-starch paste with different types of starch

In this study, the effect of different types of starch (potato, wheat, corn, tapioca, and mung bean) on the quality of three-dimensional (3D) printed food products containing tomato-starch paste (TSP) was investigated. The printability of TSP was evaluated by examining its rheological and textural properties and the microstructure of 3D printed products. The results showed that the tomato starch paste containing wheat starch had the best printing accuracy and print quality compared to the other samples, which had an extruded line width of 0.93 mm and centre heights and diameters of 18.56 mm and 20.15 mm. The macrorheological and microrheological analysis results showed that the apparent viscosity, loss modulus, storage modulus, and viscoelasticity of the TSP containing wheat starch were significantly higher than those of the other samples (P < 0.05). Low-field nuclear magnetic resonance (LF-NMR) results showed that T21 and T22 of TSP containing wheat starch significantly decreased, thereby improving the retention of printed shapes and deposition of 3D-printed TSP. The analysis of textural properties showed that TSP containing wheat starch had significantly higher strength in terms of hardness, elasticity, cohesion and chewiness, which were 9.58 N, 0.58, 0.31 and 2.13 N, respectively (P < 0.05). Thus, the pseudoplastic gel formed by TSP containing wheat starch exhibited a higher fluidity and structural density than the other samples, which improved the extrudability and shape stability of the printed product as well as the self-supporting properties of TSP.

Rheological Properties and Modification Mechanism of Emulsified Asphalt Modified with Waterborne Epoxy/Polyurethan Composite.

In research aimed at improving the brittleness of WER (waterborne epoxy)-modified emulsified asphalt, commonly encountered issues are that the low-temperature performance of this type of asphalt becomes insufficient and the long curing time leads to low early strength. Matrix-emulsified asphalt was modified with WPU (waterborne polyurethane), WER, and DMP-30 (accelerator). Firstly, the performance changes of modified emulsified asphalt at different single-factor dosages were explored through conventional performance tests and assessments of its adhesion, tensile properties, and curing time. Secondly, based on a response surface methodology test design, the material composition of the composite-modified emulsified asphalt was optimized, and its rheological properties were analyzed by a DSR test and a force-ductility test. Finally, the modification mechanism was explored by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that WER can improve the adhesion strength of modified emulsified asphalt and greatly reduce elongation at break. WPU can effectively improve the elongation at break of composite-modified emulsified asphalt, but it has a negative impact on adhesion strength. DMP-30 mainly affects the curing time of modified emulsified asphalt; EPD (composite modification) can effectively improve the high-temperature rutting resistance of matrix-emulsified asphalt, and its low-temperature performance is significantly improved compared with WER-modified emulsified asphalt. The EPD modification process mainly consists of physical blending. In the case of increasing the curing rate, it is recommended that the contents of WER and WPU be lower than 10% and 6%, respectively, to achieve excellent comprehensive performance of the composite modification.

Ecofriendly hybrid natural fiber reinforced polypropylene composites from biowastes

The used ground coffee waste (GCW) and tea leaf waste (TLW), the large wastes from the beverage process, were selected as natural reinforcement and natural pigment in the polypropylene (PP) matrix. In this work, the maleic anhydride polypropylene (MAPP) was added to the composites to develop the compatibility between fillers, fibers, and polymer matrix. The TLW/PP composites, GCW/PP composites, and GCW/TLW/PP hybrid composites were prepared in the ratio of TLW and GCW ranging from 0 to 30 wt% with the addition of MAPP at 5 wt% of fillers. The presence of GCW and TLW in the PP matrix decreased tensile properties and impact resistance but increased flexural modulus and hardness of PP at high concentrations of GCW and TLW. The increase in GCW and TLW concentration slightly reduced melting temperature but it enhanced the tensile and flexural modulus. Furthermore, it enhanced the hardness, thermal and rheological properties of the composites. The TLW/PP composites had better mechanical properties, and rheological properties than GCW/PP composites but thermal properties were quite similar. The mechanical properties of GCW/TLW/PP hybrid composites were better than those of GCW/PP composites but lower than those of TLW/PP composites. The rheological and thermal behaviour of hybrid composites were like that of TLW/PP composites. Incorporating MAPP improves the mechanical and rheological behavior of PP composites by enhancing the interaction among PP, GCW, and TLW. However, this addition does not significantly enhance the composites’ thermal properties. The optimum composite was hybrid composites of GCW/TLW/PP consisting of GCW of 10 wt%, TLW of 20 wt%, and MAPP of 1.5 wt% which presented good mechanical, thermal, and rheological properties. The mechanical properties of this hybrid composites were as follows: a tensile strength of 26.35 MPa, elongation at break of 10.91%, tensile modulus of 636.69 MPa, flexural strength of 45.57 MPa, flexural modulus of 3632.86 MPa, impact resistance of 12.72 kJ/m2, and a Shore D hardness of 76.15. The overall results showed that GCW and TLW can be used as reinforcement material and natural pigment in the polymer matrix.

Investigations on the rheological properties of cement mortar based on fine aggregate characteristic and its extended prediction model

The rheological property of mortar is significantly influenced by its contained fine aggregate morphology characteristic and capable predictive models are limited. This work aims to expand the film thickness theory by developing an index that integrally represents variations in grain shape, gradation, and mix proportions, and elucidates the impact and the mechanism of these multifactorial differences on rheological performance. The quantitative analysis of the aggregate gradation and particle shape differences were performed, which was used to assess the impact of these variations and different mix ratios on the rheological performance of mortars. A correlation between aggregate differences and film thickness was established using specific surface area and void ratio. The result shows that variations in aggregates are accurately assessed by image analysis and consistently reflected in specific surface area and void ratio metrics. Since variations in rheological performance are predominantly governed by differences in film thickness, the disparities among aggregates can be quantified in terms of their impact on rheological properties by considering specific surface area and void ratio, thus translating into variations of film thickness. The differences in rheological properties due to variations in grain shape, gradation, and mix proportions can be comprehensively represented and controlled through an expansion of the film thickness model.

Rheological, Thermal and Physicochemical Properties of Bioprocessed Flour From Cowpea, Sorghum and Orange Fleshed Sweet Potato

ABSTRACTThis study investigated the rheological, physicochemical, and thermal properties of fermented and germinated whole reddish‐brown cowpea, white sorghum and orange‐fleshed sweet potato. Germination substantially reduced the pasting and rheological attributes of flour suspensions compared to the fermentation process. This study observed notable increases in the hot paste, setback, and final viscosities after the fermentation of cowpea and sorghum, indicating an improvement in the ease of cooking and greater retrogradation tendency of starch molecules. Among the fermented flours, sorghum had the highest hot paste viscosity (848 mPa s) and final viscosity (1451 mPa s). The mechanical fingerprint revealed a viscoelastic solid character, with G′ &gt; G″ over the frequency range of 0–10 rad/s for all samples. Temperature sweep data showed a sharp increase in G′ at about 80°C, corresponding to the onset of starch gelatinization. Shear‐thinning behavior was observed, except in germinated and raw sorghum flours, where molecular rearrangement resulted in an initial viscosity rise at a low share rate (&lt; 20 s−1). Differential scanning calorimetric analysis revealed a marginal variation in the peak transition temperature of gelatinization (98°C–104°C for all flours except raw sorghum flour, 83.87°C). The fermented sweet potato flour indicated good flour particle flowability expressed as Carr's compressibility index (30.99) and the Hausner ratio (1.45); however, the available reducing sugars could have influenced its high percentage solubility (49.83%), thus impacting low pasting viscosities. The contrasting technological features suggest an avenue to intensify efforts in exploring composite bioprocessed flours for applications in novel foods.

Soluble and insoluble dietary fiber at different ratios: Hydration characteristics, rheological properties, and ameliorative effects on constipation

The proportion of soluble components in dietary fiber is an important factor affecting its physicochemical properties and physiological functions. The influence mechanisms of insoluble (IDF) and soluble dietary fiber (SDF) at different ratios on constipation were investigated. Results showed that SDF had higher active groups and water swelling capacity than IDF. The viscosity of chyme with SDF alone was the highest in oral and gastric phases. The gastric emptying rate and small intestine propulsion capacity increased significantly, especially when IDF/SDF was 1:1. IDF and a lower proportion of SDF (< 50 %) promoted gut microbiota diversity and short-chain fatty acids production. The contents of 5-hydroxytryptamine, acetylcholinesterase and gastrin reached the maximum value when the IDF ratio was 50 %. In conclusion, IDF could act synergistically with SDF to promote defecation and relieve constipation, and the effect was the best when the ratio of IDF to SDF was 1:1.

Relationship between rheological parameters and structure formation in high moisture extrusion of plant protein biopolymers

High moisture extrusion (HME) is widely employed to texturize plant-derived protein ingredients, but its development is still much based on trial and error. In this project, it was hypothesized that the rheological properties of plant-based mixtures analyzed when in the molten state and during their cooling can aid in understanding their structure formation. To test this hypothesis, biopolymer formulations containing pea protein isolate (PPI) were examined at different moisture and starch contents, and their rheological properties were analyzed using a closed cavity rheometer (CCR) at temperatures relevant to those applied during HME processing. The results obtained with the CCR were then contrasted with the mechanical properties of HME obtained using a lab scale extruder, measured using oscillatory rheology, large deformation, and dynamic mechanical analysis. Low moisture (55 %) HMEs were stiff and brittle, while high moisture (65 %) HMEs formed more flexible and anisotropic structures. Addition of starch created softer structures. The viscoelastic properties of the biopolymer mixes measured with the CCR were correlated with the mechanical parameters of the final extrudates. Strong correlations were found between small deformation rheological parameters measured in the CCR and the hardness values, while non-linear viscoelastic parameters were correlated with anisotropy indexes. Results demonstrated that the material properties measured at the early cooling stages strongly influence the structural heterogeneity in HMEs. This study highlights the potential to use the viscoelastic properties of the biopolymer mix measured with the CCR to predict their structural features when processed by extrusion.

Use of a hydrosilylation reaction for the preparation of structure-controlled boroxine-based polyborosiloxanes

The structure of organosilicon vinyl-containing boroxine was confirmed by 1H nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Its thermal properties were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) methods. The ability of boroxine to undergo hydrosilylation using the Karstedt's catalyst was investigated on various organosilicon substrates. Boroxine was shown to be involved in these reactions as a cross-linking agent. The formation of dynamic boroxine cross-links allowed the analysis of the reaction products by NMR spectroscopy, including the use of polyfunctional hydride-containing reagents. In all cases the addition proceeds selectively to the β-position and with complete conversion. The structure of the resulting polyborosiloxane containing 1.4 mol% of modified units was also confirmed by 1H NMR spectroscopy, and its thermal and rheological properties were studied.

Effect of lubricants type and particle size on the rheological properties and aerosolization behavior of dry powder inhalers

A commonly used strategy to improve aerosolization behavior of carrier-based dry powder inhalers (DPIs) is the addition of magnesium stearate as a lubricant, yet it may also negatively affect properties of DPIs. Thus, the aim of this study was to find lubricants that could be used as alternatives of magnesium stearate and meanwhile verify the applicability of using powder rheological properties to predict the performance of different lubricants in DPIs. Here, using fluticasone propionate as a model drug, LH200 as the carrier, influence of lubricants type and particle size, including magnesium stearate, sodium stearate, Leucine, sodium stearate fumarate, Compritol® 888 ATO, and Compritol® HD5 ATO, on the physicochemical properties, powder rheology and aerosolization behavior of the DPI formulations was characterized. Further, the relationship between powder rheological parameters and in-vitro drug deposition parameter, fine particle fraction (FPF), were explored, and the contribution of powder flowability and adhesion was evaluated using principal component analysis (PCA). The results showed that magnesium stearate, sodium stearate and smaller sized leucine significantly reduced the basic flowability energy, aeration energy and Permeability of the DPI formulations, leading to improved aerosolization behavior. A robust linear correlation was established between rheological parameters and FPF. PCA showed that in lubricants containing formulations, the contribution of flowability (74.69%) was greater than that of adhesion (25.31%). In conclusion, sodium stearate and smaller particle size Leucine can be considered as substitutes of magnesium stearate in DPI formulations.

Bambara groundnut starch-soluble dietary fibre nanocomposite stabilised emulsions: Optimisation of emulsion stability and studies on time-dependent rheological properties

Due to their inherent thermodynamic instability, emulsions require stabilisers to maintain their integrity and prevent destabilisation. The effect of emulsion components (Bambara groundnut starch-soluble dietary fibre nanocomposite (STASOL), orange oil and water) on the rheological and stability properties of STASOL-stabilised emulsions was optimised. A randomised D-optimal exchange mixture design was used to determine the ratio of STASOL, orange oil and water required for a stable emulsion. The stability of these emulsions was evaluated using the initial mean backscattering index (BSAVO), Turbiscan stability index (TSI) and hysteresis loop area (HLA). The BSAVO (%), TSI and HLA of the emulsions ranged from 50.73% (14:30:56 STASOL:oil:water) to 70.47% (20:30:50 STASOL:oil:water), 0.0005 (20:30:50 STASOL:oil:water) to 0.1000 (8:42:50 STASOL:oil:water) and 0.37 Pas-1 (10:32:58 STASOL:oil:water) to 5.69 Pas-1 (20:30:50 STASOL:oil:water), respectively. Emulsions exhibited a direct relationship between STASOL concentration and stability metrics, with the highest stability achieved at 20% STASOL concentration, 30% orange oil and 50% water. An increase in STASOL concentration coupled with a decrease in oil concentration results in a stable emulsion. Numerical optimisation and experimental validation confirmed the effectiveness of the selected formulation, demonstrating STASOL's potential as a natural stabiliser in beverage emulsions and its ability to enhance stability compared to synthetic alternatives.

Effect of chitosan molecular weight and protein to polysaccharide ratio on the rheological and physicochemical properties of milk proteins–chitosan complex coacervate

The small amplitude oscillatory shear (SAOS) rheological properties of complex coacervate of milk proteins with high (HMC), medium (MMC), and low (LMC) molecular weight chitosan in the optimal ratios of milk proteins to chitosan (15:1, 10:1, and 5:1, respectively) were measured. In addition, the morphological (SEM), structural (XRD), and thermal (DSC) properties of the complex coacervates were investigated in comparison with the milk protein concentrate. Complex coacervates showed the shear-thinning behavior due to a linear decrease of complex viscosity with increasing frequency. Furthermore, the highest complex modulus and the more compact structure under optimal conditions, in terms of the ratio of protein to chitosan and pH, revealed strong electrostatic bonding between proteins and chitosan. All coacervates showed a G′ > G″ (Tanδ<1), indicating the formation of an interconnected gel-like structure that was described by the power law model. The maximum fracture stress was obtained at optimum conditions (R = 15:1, pH =6.7 for HMC; R = 10:1, pH =5.5 for MMC and R = 5:1, pH =4.6 for LMC), indicating the highest intermolecular interaction between milk proteins and chitosan. The coacervates had a completely amorphous structure similar to MPC, and according to DSC results, the ionic bonds between milk proteins and chitosan were not destroyed up to 300 °C. Coacervation leads to purified milk proteins at a low cost. In addition, the coacervates can be used for the encapsulation of heat-sensitive compounds, and also as a stabilizer to improve the texture of food.

Insights into the Pickering emulsions stabilized by yeast dietary fiber: Interfacial adsorption kinetics, rheological characteristics, and stabilization mechanisms

This study developed Pickering emulsions based on yeast dietary fiber (YDF) and investigated the interfacial adsorption kinetics of YDF, rheological properties and stabilization mechanisms of emulsions. Results indicated that increasing YDF concentration enhanced its diffusion and rearrangement at the oil-water interface. At a concentration of 8 %, YDF exhibited the highest diffusion rate (0.1406 mN·m−1·s-0.5) and rearrangement rate (18.8 s−1). The emulsion stabilized at this concentration had the smallest droplet size (1.55 μm) and the slowest droplet migration rate (0.34 mm/h), effectively suppressing droplet aggregation due to collisions and thereby improving the overall emulsion stability. Confocal laser scanning microscopy results confirmed that emulsion stability relied on the co-adsorption of proteins and polysaccharides from YDF at the interface, with proteins primarily adsorbed at the oil-water interface and polysaccharides responsible for the continuous phase network formation. This study demonstrates YDF's potential as an emulsion stabilizer and elucidates the stabilization mechanism of YDF-induced emulsion.

Amelioration of extremely acidic environment of soy protein amyloid fibrils to enhance gelation performance by dialysis strategy: Effects of pH and ions

The application of soy protein amyloid fibrils (SAFs) to food industrialization field has received focused attention because of their advantages such as ordered supramolecular structure and anti-proteolytic properties. However, the comparatively weak gelation properties of SAFs make it difficult to form self-supporting hydrogels, limiting its potential for future applications. Additionally, the extremely acidic environment (pH 2) of SAFs hinders their practical application in the food pH range (4-7). To address this issue, a dialysis strategy was utilized to enhance the gel structure of SAFs in this paper. The SAFs were dialyzed by deionized water and zinc ions solutions with four different pHs (2, 4, 7, and 9), and the impact of various dialysates on rheological properties, water distribution, and microstructure was investigated. The results demonstrated the method significantly improved gelation properties and modified the extremely acidic environment of SAFs. Various samples were continuously deacidified during dialysis in solutions of different pHs (4, 7, and 9), transforming from pH 2 to a higher pH value. Visual images exhibited that self-supporting hydrogels can be formed by SAFs just at a low concentration of 3% (wt). SAFs-Zn2+-9 hydrogel exhibited the highest storage modulus with a 500-fold compared to SAFs-2. Notably, the SAFs-H2O hydrogels were fabricated without any exogenous substances, in which the storage modulus of SAFs-H2O-9 increased by over 300 times. AFM images demonstrated that the shift from long rigid fibrils to short flexible fibrils induced tightly entanglement among fibrils, which improved gelation performance. Moreover, the transform in pH and the incorporation of ions caused the hydrogels to show dense network structure and strong water retention capacity. The ingenious insights were provided for improving the gelation performance of SAFs and modifying the polar acidic environment in the study, fully exploiting the potential of SAFs as edible ingredients for food applications.

Understanding the time-dependent rheological behavior of seawater mixed cement paste with fly ash

Due to the relative scarcity of freshwater resources in coastal regions, the use of seawater in concrete construction has great potential due to its benefits in cost and resource. To further advance the application of seawater concrete, a deeper understanding of its rheological properties is essential. This study investigates the effects of fly ash on the time-dependent rheological behavior of seawater cementitious paste, such as yield stress, plastic viscosity, and structural build-up rate. The underlying mechanisms are analyzed using the theories of water film thickness (WFT), ion concentration, and hydration heat. The research findings confirm that the rheological parameters of seawater paste are generally higher than those of deionized water paste, regardless of the cementitious compositions. As fly ash content increases, the plastic viscosity of seawater paste increase, while the fluidity and dynamic yield stress decreases. Further analysis reveals that the decrease in the yield stress with fly ash content is well related to the increase in the WFT, but it cannot sufficiently explain the change of yield stress over time. Instead, the amount of hydration products in seawater paste shows a linear increasing relationship with the dynamic yield stress at 65 min. By contrast, the plastic viscosity can be related to the ion concentration in the interstitial solution, wherein an increase in the concentration of Ca2+ corresponds to an increase in the plastic viscosity. Moreover, the rheological parameters increase over time, with the growth rates between 5 and 35 minutes being higher than those between 35 and 65 minutes, possibly due to the rapid early hydration of the binder materials. This study offers a fundamental theoretical support for the use of seawater in various concrete applications.

Preparation and characteristics of tea water-insoluble protein/chitosan composite particles

The emulsifying properties of tea water-insoluble protein particles (TWIPs) are insufficient to expand their applicability in food emulsifying systems. This study aimed to explore the emulsification characteristics and application of tea water-insoluble protein/chitosan composite particles (TCPs). Scanning electron microscopy showed the TWIPs were tightly coupled with chitosan (CS). The transform of secondary structure and amino acid residues were beneficial to the formation of TCPs and improvement of emulsification performance. Increasing the CS concentration improved the viscoelasticity, as verified by rheological property, and decreased the droplet size of Pickering emulsions (PEs) at a TWIP-CS mass ratio of 50:50. In addition, when the fixed TWIP-CS ratio was 50:50, the TCPs concentration of 0.5% favored the formation of bovine bone white soup with extraordinary emulsification stability (p < 0.05). In conclusion, the emulsification property of TWIPs was improved at a TWIP-CS ratio of 50:50, which was also verified in PEs and bovine bone white soup. This work provided a theoretical basis for the development and further deep processing of tea by-products, and broadened the application of tea protein in liquid emulsification system.

Maltogenic amylase and glucosyltransferase synergistically control the chain structure of rice starch and their effects on rheological properties and functional characteristics of rice milk

Maltogenic amylase (MA) and glucosyltransferase (TG) were used synergistically for the development of rice milk products with low glycemic index (GI), and its storage properties and nutritional functions were evaluated. The structural results showed that MA and TG treatment could effectively reduce the molecular weight of rice starch and increases its overall branching degree, which further affected the storage and nutritional properties of rice milk products. Compared with gelatinized rice milk and rice milk treated with MA or TG, MTRM (treated with MA and TG) had lower paste viscosity, stable storage modulus, and stronger ability to bind water during storage period, indicating that the dual-enzyme treatment significantly improved the retrogradation properties of rice milk and the anti-retrogradation rate reached 76.12%. In vitro studies showed that dual-enzyme treatment significantly increased the resistant starch content of rice milk to 39.46%, thereby reducing its predicted glycemic index to 53.85, improving its antioxidant properties and contributing to the proliferation of short-chain fatty acids produced bacteria. Notably, MTRM significantly elevated butyrate content which showed a better prebiotic effect. This research provides new approaches for the preparation of low-GI rice-based beverages.

Machine-Learning Approach PredictsGel Strength of Drilling Fluid While Drilling

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 35433, “Novel Machine-Learning Approach for Predicting the Gel Strength of the Drilling Fluid While Drilling,” by Ahmed Gowida, SPE, and Salaheldin Elkatatny, SPE, King Fahd University of Petroleum and Minerals. The paper has not been peer reviewed. Copyright 2024 Offshore Technology Conference. _ Accurately estimating gel strength is paramount for optimizing drilling operations and preventing cuttings from settling at the wellbore’s bottom. Traditional methods rely on rotational viscometers, which are time-intensive, equipment-dependent, and lack real-time monitoring capabilities. This study underscores the feasibility of leveraging machine learning (ML) as a practical tool for predicting drilling-fluid gel strength, offering real-time monitoring and precise predictions to enhance drilling efficiency, safety, and automation initiatives. Background The gel strength of drilling fluid is assessed using a viscometer, focusing on the 3-rev/min reading obtained after agitating the fluid at 600 rev/min to disrupt any gel formation. Initially, the measurement is taken when the mud reaches a static state for 10 seconds. Subsequent readings are conducted at 10- and 30-minute intervals. The rationale behind the 30-minute reading lies in its ability to indicate whether the mud forms a substantial gel during prolonged static periods, such as when tripping out a bottomhole assembly. Elevated gel strength may result in increased pump pressure required to restore circulation after extended static conditions. Additionally, a consistent upward trend in the 30-minute gel strength suggests the accumulation of ultrafine solids. Consequently, appropriate measures such as chemical treatments or dilution with fresh base fluid are necessary to address this issue. The frequency of measuring various fluid properties is tailored to their respective effects on well-control and drilling operations. These frequent evaluations allow for timely adjustments and monitoring of rheological measurements, offering valuable insights into rock sensitivity and the performance of mud activity and stability after exposure to drilled formations. On the other hand, a complete mud test (including all mud rheological properties) is performed twice a day because it consumes considerable time. It has been observed that mud rheological properties exhibit a significant correlation with two fundamental mud properties: mud weight and Marsh funnel (MF) viscosity. To the best of the authors’ knowledge, a dearth of research exists in the literature aimed at predicting the gel strength of drilling fluid using ML techniques. Consequently, this research endeavor introduces a novel ML model designed specifically for forecasting the gel strength of synthetic oil-based mud systems. Such predictive models are poised to enhance drilling performance by optimizing mud functions. Leveraging MF and mud-density measurements, the developed models aim to forecast the rheological properties of drilling fluid, thereby facilitating improved monitoring of mud functionality during drilling operations at the rig site.

Effects of sodium chloride on the textural attributes, rheological properties, microstructure, and 3D printing performance of rice starch-curdlan composite gel

This study explores the impact of varying concentrations of salt ions (0, 2.5, 5, 7.5, 10, and 12.5 mmol) on the physicochemical properties and 3D-printing performance of rice starch-curdlan composite gel. The relationship between gel structure, properties, printability, and printing accuracy was clarified through the evaluation of each parameter. The inclusion of an appropriate concentration of NaCl positively influenced the properties and printing characteristics of the composite gel. Specifically, a NaCl concentration of 7.5 mmol yielded the highest printing performance, achieving 98.61 % accuracy. Microstructural analysis indicates that the addition of ions promoted the formation of a denser network structure in the composite gel. Fourier-transform infrared spectroscopy reveals enhanced hydrogen bonding in the rice starch-curdlan gels with the addition of NaCl. Lastly, dysphagia testing demonstrates that the composite gels with 0–5 mmol NaCl concentrations exhibited grade 5 characteristics (clastic and wet) with satisfactory swallowing performance.

Extrudability analysis of 3D printable concrete as a two-phase discrete flow

3D printing with concrete is primarily achieved through an extrusion process, where the material is precisely deposited layer by layer to construct structures. Proper control of extrusion ensures consistent material flow, accurate layer formation, and the overall stability of the 3D-printed structure. However, clogging during the extrusion process can occur as the nozzle size is too small relative to the aggregate size. To fundamentally understand the clogging mechanism and optimize the extrusion process, a precise two-phase discrete element model was established to simulate the extrusion process. A cluster of particles was used to model fresh concrete, with hard cores representing the aggregates and concentric soft shells representing fresh cement paste surrounding them. Five nozzles with different outlet diameters were designed and 3D printable concrete with different fineness modulus levels was formulated. The parameters of the two-phase discrete element model were determined based on rheological properties and calibrated using slump flow test results. The simulation results showed good agreement with the experimental pressure values and the quality of extruded filaments. Based on these results, it suggested that ensuring a proper balance between the aggregate fineness modulus and the outlet diameter of printing nozzles is essential for the extrusion process.

Drying of avocado peels using carbonation-ultrasonication as pretreatment: energy consumption, antioxidant capacity and rheological properties

Fruit processing by-products, especially peels are underused and mostly discarded as waste. The aim of this study was to assess the effect of ultrasonication (US) combined with carbonation (CUS) on the convective drying process of avocado peels at different temperatures, adding value to this waste. For this, the avocado peels were treated with dry ice for 15 min and subjected to US (400W/10 min, 30°C) before convective air drying (50-70°C). The energy consumption, antioxidant capacity, water adsorption isotherms, rehydration rate, and dynamic rheology of dried avocado peels pretreated by CUS were compared with a control process (without pretreatment) and only US pretreatment. The combined treatment (CUS70) resulted in a 2.6-fold reduction in drying time and a 2.3-fold decrease in energy consumption, with CO2 preserving bioactive compounds and antioxidant capacity after the drying process. Differences were also observed in the rehydration capacity of the samples (CUS), with an increased water absorption capacity, along with a reduction in the viscoelastic properties of the peels. The results present new perspectives for the application of CUS in the food industry, paving the way for the development of creative, innovative, and simple approaches for the management and recycling of agri-food waste, with the potential to extend this knowledge to new food matrices.