Rheological Evaluation Research Articles

Injectable polysaccharide hydrogels as localized nitric oxide delivery formulations.

A series of injectable polysaccharide hydrogels were prepared with oxidized dextran and diethylenetriamine-modified carboxymethylcellulose or hyaluronic acid. Rheological evaluation revealed that carboxymethylcellulose-based hydrogels achieved the largest storage moduli (>1 kPa) when prepared from 5 wt. % solutions. However, carboxymethylcellulose-based hydrogels with storage moduli >100 Pa were prepared from solutions with concentrations as low as 2 wt. %. Hyaluronic acid-based hydrogels demonstrated smaller storage moduli but had swelling ratios more than four times that of the carboxymethylcellulose systems at the same polymer concentrations. The incorporation of N-diazeniumdiolate NO donors into the hydrogels resulted in reduced hydrogel storage moduli as a function of NO donor concentration. The impact of the hydrogel architecture on NO-release kinetics proved dependent on the identity of the NO donor. Hydrogel degradation over 14 d was measured at pH 5.4 and 7.4 and indicated that hyaluronic acid-based hydrogels degraded more rapidly than carboxymethylcellulose hydrogels and that the addition of NO to the hydrogels increased the rate at which they degraded. In vitro cytotoxicity of hydrogel extracts was evaluated against five cell lines, with no observed toxicity except for that of hyaluronic acid-based hydrogel extracts against human gingival fibroblasts. The diverse properties, versatility, and non-toxic characteristics of these injectable hydrogels should facilitate local delivery of nitric oxide for a range of biomedical applications.

Soy Protein Isolate as Emulsifier of Nanoemulsified Beverages: Rheological and Physical Evaluation.

The production of biologically active molecules or the addition of new bioactive ingredients in foods, thereby producing functional foods, has been improved with nanoemulsion technology. In this sense, the aim of this work was to develop nanoemulsified beverages as potential candidates for the encapsulation of bioactive compounds, whose integrity and release across the intestinal tract are controlled by the structure and stability of the interfaces. To achieve this, firstly, a by-product rich-in protein has been evaluated as a potential candidate to act as an emulsifier (chemical content, amino acid composition, solubility, ζ-potential and surface tension were evaluated). Later, emulsions with different soy protein isolate concentrations (0.5, 1.0, 1.5 and 2.0 wt%), pH values (2, 4, 6 and 8) and homogenization pressures (100, 120 and 140 PSI) were prepared using a high-pressure homogenizer after a pre-emulsion formation. Physical (stability via Backscattering and drop size evolution) and rheological (including interfacial analysis) characterizations of emulsions were carried out to characterize their potential as delivery emulsion systems. According to the results obtained, the nanoemulsions showed the best stability when the protein concentration was 2.0 wt%, pH 2.0 and 120 PSI was applied as homogenization pressure.

Application of Calcium Alginate Hydrogels in Semisolid Extrusion 3D Printed for the Production of Easy‐to‐Swallow Tablets

To maximize the potential of 3D printing, several technological issues must be overcome, especially in the case of semisolid extrusion (SSE), where the 3D model is built up through the well‐defined extrusion of polymeric ink. Focusing on natural polymers, their physicochemical properties should be deeply investigated to evaluate 3D printability. This study aims to produce tablets easy to swallow, exploiting as 3D printing ink a crosslinked alginate hydrogel added of sorbitol, speculating that the plasticising action of sorbitol should allow to improve tablets’ swallowability. Three different amounts of 70% sorbitol solution (5%, 15%, 25% v/v) are evaluated to identify the best composition in terms of both printing and technological properties. The data obtained from the chemical, rheological, and mechanical evaluation of each ink are related to the printing performance, to reach the best manufacturing reproducibility. Linear regression fitting study (r 2 = 0.9982) confirms the predictable relationship between residual mass of final platforms and sorbitol amount loaded. To characterize the final products, all dried batches are subjected to technological evaluation highlighting differences in the matrix softability as well as in the swelling/erosion properties after the interaction with biological fluids.

Locust bean gum hydrogels are bioadhesive and improve indole-3-carbinol cutaneous permeation: influence of the polysaccharide concentration

The locust bean gum (LBG) is a polysaccharide with thickening, stabilizing and gelling properties and it has been used in the preparation of pharmaceutical formulations. Hydrogels (HGs) are obtained from natural or synthetic materials that present interesting properties for skin application. This study aimed to develop HGs from LBG using indole-3-carbinol (I3C) as an asset model for cutaneous application. HGs were prepared by dispersing LBG (2%, 3% and 4% w/v) directly in cold water. The formulations showed content close to 0.5 mg/g (HPLC) and pH ranging from 7.25 to 7.41 (potentiometry). The spreadability factor (parallel plate method) was inversely proportional to LBG concentration. The rheological evaluation (rotational viscometer) demonstrated a non-Newtonian pseudoplastic flow behavior (Ostwald De Weale model), which is interesting for cutaneous application. The HET-CAM evaluation showed the non-irritating characteristic of the formulations. The bioadhesive potential demonstrated bioadhesion in a concentration-dependent manner. Permeation in human skin using Franz cells showed that the highest LBG concentration improved the skin distribution profile with greater I3C amounts in the viable skin layers. The present study demonstrated the feasibility of preparing HGs with LBG and the formulation with the highest polymer concentration was the most promising to transport active ingredients through the skin.

Rheological properties of dry-fractionated mung bean protein and structural, textural, and rheological evaluation of meat analogues produced by high-moisture extrusion cooking

A closed cavity rheometer was used to study the rheology of dry-fractionated mung bean protein –DFMB– (55% protein d.m.). Then, the high-moisture extrusion cooking at 40% and 50% moisture contents and different temperatures (115, 125, 135 and 145 °C) was performed, investigating the impact on structural, textural, and rheological properties of extrudates. When subjected to a temperature ramp (40–170 °C), DFMB showed an increase of G* from 70 °C, as a consequence of starch gelatinization and protein gelation. The peak, indicating the end of aggregation reactions, was at 105 °C and 110 °C for DFMB at 50% and 40% moisture content, respectively. The time sweep analysis described the protein behavior in no-shear/shear conditions, highlighting a more pronounced effect of the temperatures compared to moisture content. During the extrusion cooking, the temperature increase led to a decrease of pressure, indicating a reduction of the melt viscosity. The microstructure of the extrudates showed a more pronounced anisotropic profile when higher temperatures were applied. Hardness, chewiness, and cohesion were directly correlated with the temperature, which also affected the rheological properties of extrudates. A combination of textural and rheological analyses can offer a clear overview of the structural characteristics of meat analogues.

Incorporation of the Multi-Layer Plastic Packaging in the Asphalt Binders: Physical, Thermal, Rheological, and Storage Properties Evaluation.

The amount of residual Multi-layer Plastic Packaging (MPP) in Canada has greatly increased in the last two decades, which has economic and environmental consequences. MPP is primarily made up of two or more layers of Polyethylene (PE), Polyester (PET), Nylon (NY), and Metalized Polyester (METPET). While MPP has not been used as an asphalt modifier, some of the materials commonly found in MPP, such as PE and PET, have also been successfully used as asphalt modifiers. Nevertheless, a few recent studies have demonstrated the potential for reusing MPP as an asphalt modifier to improve asphalt pavement performance. Recycling post-industrial MPP instead of using raw polymers could lead to economic and environmental benefits. However, a comprehensive study to evaluate MPP as a viable asphalt additive is lacking. The main objective of this study is to evaluate the feasibility of using MPP as an asphalt modifier via the wet method, considering the physical, thermal, rheological, and storage properties of the MPP-modified binder at different MPP concentrations (2%, 4%, and 8%) in asphalt cement (PG 58-28). MPP-modified binders were evaluated using the following instruments: Differential Scanning Calorimeter (DSC), Thermogravimetric Analysis (TGA), Superpave Dynamic Shear Rheometer (DSR), Rotational Viscosity (RV), and Environmental Scanning Electron Microscopy (ESEM). Test results indicated that the incorporation of MPP has a strong potential to improve permanent deformation resistance at high temperatures. In addition, MPP shows a moderate impact on fatigue cracking performance at intermediate temperatures. Overall, in low-temperature climates, using less than 4% of MPP additives would offer higher fatigue damage resistance along with adequate permanent deformation. In high-temperature climates, higher concentrations of additives may be preferable to resist permanent deformation. Finally, MPP is a challenge for existing recycling systems, and its incorporation into asphalt applications may develop more sustainable materials that would contribute to circular economy principles.

Composite Asphalt Modification with Waste EPDM Rubber and Tire Pyrolytic Oil: Rheological, Chemical, and Morphological Evaluation

Waste ethylene-propylene-diene monomer (EPDM) rubber and tire pyrolytic oil (TPO) derived from waste tire pyrolysis have shown promising results for their use in asphalt binder modification. However, their incorporation has shown improvements mainly either on rutting or fatigue behavior of the resultant asphalt binders. Composite modification may be a viable option to achieve improved performance with these two materials. The aim of this study was to evaluate the rheological, morphological, and chemical properties of asphalt binders produced through both individual and composite modifications using waste EPDM rubber and TPO. For composite modification, two different blending schemes were used: (1) sequential addition of TPO and EPDM rubber to the heated base asphalt binder; and (2) premixing of TPO and EPDM rubber prior to addition to the heated base asphalt. In the latter case, before being added to the base asphalt, TPO premixed EPDM rubber was conditioned at two temperatures (25°C and 90°C) to see the effect of different conditioning temperatures in composite modification. Firstly, the conventional properties of all the binders in the unaged state were assessed, followed by the evaluation of short-term-aged binders for Superpave and Shenoy rutting parameters, frequency sweep, zero shear viscosity, multiple stress creep and recovery, and Burger’s modeling. The long-term-aged binders were evaluated through the Superpave fatigue parameter, Glover-Rowe parameter, and linear amplitude sweep. Fourier transform infrared (FTIR) spectroscopy and optical microscopy were used for chemical and morphological analyses. The premixing of EPDM and TPO accompanied with conditioning at 90°C imparted a synergistic effect with improvements in both rutting and fatigue performance of binder. The improvement in performance attributes was ascribed to the preswelling of EPDM rubber with TPO, which was evident from the morphological analysis. FTIR provided evidence of chemical interaction between EPDM rubber and TPO during the conditioning and blending processes.

Effect of ultrasound pretreated hydrocolloid batters on quality attributes of fried chicken nuggets during post-fry holding.

In this study, batters formulated with different hydrocolloids (i.e., pectin, locust bean gum, xanthan gum, guar gum, hydroxypropyl methylcellulose and methylcellulose) were treated with ultrasound as edible coatings for fried chicken nuggets. Quality characteristics (i.e., batter pickup, flow behaviours, thermal properties, moisture loss, color and textural properties) in chicken nuggets coated with ultrasound treated batters were evaluated before and after post frying exposure to heat lamp. Ultrasonication significantly reduced batter pickup, flow behavior and gelatinization enthalpy, revealing its tendency to alter functional properties of batter systems. Rheological evaluation of all batter samples revealed a pseudoplastic (shear thinning) flow characteristic when fitted to power law model, with ultrasonicated (US) samples exhibiting a significantreduction in viscosity over non-ultrasonicated (NUS) samples. Compared to the control NUS, fat content of chicken nuggets coated with US-treated batters decreased by 39.0, 60.9, 62.87, 64.1, 65.7, and 65.0 % for pectin, locust bean gum, xanthan gum, guar gum, hydroxypropyl methylcellulose and methylcellulose, respectively. Finally, chicken nuggets coated with US and NUS treated batters exhibited greater cutting force values immediately after frying but declined within the first 10min of heat lamp exposure and increased subsequently with extended heat lamp holding time. Furthermore, NUS-treated guar gum resulted in chicken nuggets with the most minimal variability in cutting force during post-frying holding, indicating that crispiness was maintained. Overall, application of ultrasound as a batter pretreatment technique can be exploited by the frying food industry as an alternative approach to producing low fat chicken nuggets with appreciable quality attributes.

Chemical and rheological properties evaluation of a novel synchronous rejuvenated aged SBS modified asphalt

The aging hardening of neat asphalt binder and the aging degradation of styrene-butadiene-styrene (SBS) polymer could significantly shorten the service life of the SBS modified asphalt (SBSMA) pavement and produce vast waste asphalt pavement materials. In order to recycle and reuse the aged SBSMA in a sustainable way, a green compound rejuvenator, which consists of aromatic oil and triallyl isocyanurate (TAIC), was developed to restore the original properties of the aged SBSMA based on the synchronous rejuvenating mechanism (i.e., colloidal structure regulation and SBS polymer structural reconstruction). The rejuvenating efficiency of the newly developed compound rejuvenator was first verified by fluorescence images, functional group characteristics, and molecular weight distributions of the SBSMA before and after rejuvenation. The rheological properties of the synchronous rejuvenated SBSMA (SRSBSMA), including the high-temperature permanent deformation resistance, low-temperature anti-cracking resistance, and fatigue resistance performance, were subsequently tested and compared with those of the SRSBSMA developed in previous studies. The results showed that aromatic oil had the capability to stabilize the unbalanced colloidal structure of the aged neat asphalt binder, while TAIC underwent a chemical reaction with the active group of the aged SBS to reconstruct the crosslinking network structure of the SBS modifier. Additionally, the rheological test results indicated that the performance of SRSBSMA restored by the new compound rejuvenator was the closest one to that of the virgin SBSMA as compared with the existing rejuvenators. To this end, the newly developed compound rejuvenator is proven to be promising in restoring the properties of SBSMA, which thus can be used to efficiently rejuvenate the aged SBSMA pavement.

The effect of the structural transition within a direct hexagonal (HI) mesophase on the internal lipid mobility

The current study analyzes the cause of the extreme change in dermal permeation resulting from a minute structural transformation within a temperature-sensitive direct hexagonal mesophase by a multiple-method approach. The evaluated mesophase is composed of Tween 80, propylene glycol, isopropyl myristate, benzyl alcohol, and water. 1 wt% ketoconazole (KCZ) was loaded in the concentrate as a model lipophilic drug. Evaluation of the mesophase at 25 °C indicated that the hexagonal mesophase region (33.0–42.5 wt% water along water dilution line N91) consists of two distinct structures. At water content below 39.0 wt%, the mesophase is structured as a bidiscontinuous hexagonal mesophase (BHM) consisting of occluded hydration centers and hexagonally oriented direct micelles. Above 39.5 wt% water, dilution of the BHM obstructs the hydration centers, transforming the mesophase to a water continuous hexagonal mesophase (CHM). FTIR evaluation indicated that the both the added water upon dilution and the water molecules released from the hydration centers bind to the surfactant's non-hydrated ethoxylates. Evaluation of the structural transition by PGSE-NMR and DSC indicated that the binding of water to the surfactant's heads immobilizes the inner core of the solubilized lipids. The reduction of the lipid core’s mobility prevents its crystallization at cryogenic temperatures. SAXS and rheological evaluations pointed out that both BHM and CHM are temperature-sensitive mesophases, which lose their range order and storage modulus at 32 °C. Obstruction of the hexagonal mesophase enhances KCZ's diffusion from both mesophases’ via cellulose acetate at 35 °C. Despite the similarity of both mesophases at elevated temperatures (35 °C), the lipidic inner core’s rotational correlation time for deformed CHM micelles remains substantially lower than from the deformed BHM. Franz cell evaluation indicated that the lipidic core mobility substantially influences KCZ's distribution upon dermal application, whereas from CHM KCZ's transdermal flux via a dermatome bovine graft at 35 °C, was 1.60 ± 0.28 µg/cm2 h, no flux was detected from BHM. On the other hand, KCZ's dermal accumulation from BHM, at 35 °C, was found to be more than double than that from CHM, indicating that the decrease in the lipidic inner core’s mobility of direct micelles prevents the accumulation of lipophilic compounds in the dermis, thereby enhancing their transdermal flux.

Development of a new rejuvenator for aged SBS modified asphalt binder

The objective of this study is to evaluate the effectiveness of active reagents (i.e., methylene-bis(4-cyclohexylisocyanate) (HMDI) and 1,6-hexanediol diglycidyl ether (HDE)) and epoxidized soybean oil (ESO) in rejuvenating aged styrene-butadiene-styrene (SBS)-modified asphalt binder (SBSPAV) by promoting the interaction of aged binders with virgin asphalts. To achieve this objective, a multidisciplinary approach combining chemical and engineering methods was adopted. The chemical characterization of asphalt binders includes SARA fractionation (saturates, aromatics, resins and asphaltenes) and Fourier transform infrared spectroscopy (FTIR) tests. Rheological evaluation of the asphalt binders was utilized assessing fatigue, rutting, and thermal cracking resistance. The results indicated that the addition of ESO helped to adjust the low temperature performance of SBSPAV. Compared to SBS-modified asphalt (SBSMA), the low temperature relaxation modulus of ESO-rejuvenated asphalt has a 35.8% reduction. Whereas the addition of ESO alone could did not restore the performance of the SBSPAV. The addition of HMDI and ESO could improve the high-temperature performance of SBSPAV. Compared to SBSMA at 52 °C, the rutting factors of HMDI-rejuvenated asphalt with 0.5% and 1.0% were improved by 43.12% and 97.86%, respectively. According to the MSCR results, with a 1.0% content, the recovery rates of HDE-rejuvenated asphalt and HMDI-rejuvenated asphalt increased by 8.2% and −23.4%, respectively. The rejuvenated binders with HMDI showed better elastic recovery properties and permanent deformation resistance than the other studied binders. HMDI can increase the asphaltene content in rejuvenated asphalt, while HDE can increase the aromatic fraction content in rejuvenated asphalt, according to the SARA fraction results. The asphaltene content of 1.0% HMDI-rejuvenated asphalt increased by about 2.13%, and the aromatic content of 1.0% HDE-rejuvenated asphalt increased by about 3.46%. The FTIR results showed that HMDI chemically reacted with SBSPAV to form carbamate bonds with a stable chemical structure, and both HMDI and HDE could partially restore the broken chain structure of SBS. Overall, the results indicated that HMDI and HDE (combined with ESO) have the potential to be used to rejuvenate SBSPAV and that the recommended optimum contents for HMDI and HDE are 0.5%–1.0%.

Formulation and rheological evaluation of liposomes-loaded carbopol hydrogels based on thermal waters

The aims of this study were to develop topical liposomal hydrogels based on thermal waters (TWs) acquired in the region of Biskra (Northeast Algeria) and also to investigate their rheological properties. Liposomes containing two highly mineralized thermal waters, Baraka (BTW) and Salhine (STW), were prepared by probe sonication using phosphatidylcholine (PC) and cholesterol (Chol), plain or mixed with phosphatidylglycerol (PG). Based on their lipid composition, obtained liposomes presented vesicle sizes of 60 nm, a low polydispersity index, and various negative zeta potentials. It was noted that with increasing counterions charge in TWs the zeta potential of liposomes decreased toward neutral values. Carbopol (1%, w/w) hydrogels prepared with BTW, STW, and also demineralized water (placebo hydrogel) showed a non-Newtonian behavior, pseudoplastic fluid adjusted to Carreau model. The composition of thermal waters influenced highly the rheological properties of Carbopol hydrogels. Liposomal hydrogels were prepared by dispersing liposomes in hydrogels formulated with the same encapsulated thermal water. Regardless of composition or lipid concentration of added liposomes, the viscosity and viscoelastic parameters of Carbopol hydrogels changed negligibly. Indeed, liposome composition and lipid concentration seemed to have no effect on the rheological properties of Carbopol hydrogel in the presence of an important charge of cations. Hence, hydrogels and liposomal hydrogels based on thermal waters had suitable rheological properties for topical application and delivery of minerals in the skin.

Chemical-physical characteristics of artificial saliva substitutes: rheological evaluation.

We aimed at evaluating some chemical-physical properties of artificial saliva substitutes easily available on the E.U. market, such as viscosity, pH, buffering capacity, superficial tension, density and spinnbarkeit and to compare the results with human natural saliva bibliographic data. Based on the easy availability on the market, twelve artificial saliva solutions in liquid formulation were analyzed. Kinematic viscosity (cSt) was determined using a micro-Ubbelohde model capillary viscosimeter (ViscoClock, SCHOOT-GERATE Mainz, Germany). Dynamic viscosity (mPas) was determined, through a simple multiplication between density (g/cm3) and kinematic viscosity of each solution. pH analyses were carried out at room temperature using a pH-meter (Mettler Toledo®- Five Easy, Columbus, OH, USA). Spinnbarkeit analysis was performed by a self-owned instrument built for the purpose. The median density value, obtained from the cohort of artificial saliva substitutes, was 1.036 g/cm3. The median value of the kinematic viscosity was 8.984 cSt. The median spinnbarkeit value was 3.2 mm and the median pH value was 6.29. In this study we found an almost linear correlation between the kinematic viscosity and spinnbarkeit values of the artificial saliva substitutes evaluated. Saliva substitutes should be as faithful as possible to the characteristics of human saliva, in order to completely replace its functions in the oral cavity. Nevertheless, despite several R&D efforts, it is difficult to reproduce all the different features that belongs to natural saliva in one device. Therefore, it would be desirable to create more products reproducing saliva with various rheological characteristics in respect of the main salivary functions such as: chewing, speaking and tissue coating.

Evaluation of rheology and printability of 3D printing nutritious food with complex formulations

Understanding rheological properties and printability of complex food formulations is crucial for 3D printing. While nutritious formulations have been reported in the literature, these are still scarce when compared to the non-nutritious ones. These so-labeled nutritious formulations are achieved with few ingredients, leading to less challenging printability issues. The nutritious formulations presented here are reported for the first time and include up to 9 ingredients, including by-products (orange peel) and sustainable proteins (insect flour). This work aimed to evaluate and to correlate the printability and the rheological properties of nutritious complex food formulations. The concentration of pregelatinized corn starch (4–10% (w/w)) and printing temperature (27–47 °C) were varied. Rheological characterization of the studied food inks (i.e., amplitude sweep, shear-viscosity test, shear-recovery test, time-dependent shear test, temperature ramps, temperature sweep in the oscillatory mode) was performed. Printability was evaluated via a digital image analysis of the geometric features of the printed structures. An increment in the concentration of pregelatinized starch (from 4% to 10%) raised the yield stress and the storage modulus from 87.5 to 883.2 Pa and from 1004.9 to 2620.9 Pa, respectively. However, high values of rheological parameters did not correspond to an improved printability. For instance, the printability evaluation showed that formulations with 6% and 8% of pregelatinized starch were more suitable for printing than the one with 10%. Finally, initial mathematical correlations between rheology and printability were obtained and could be of benefit to potentialize complex food printing systems. The results presented showed that both, rheology, and printability analyzes, must be performed when printing complex formulations towards the development of personalized food items. More research in this regard is needed to develop new methodologies for the evaluation of 3D printing materials.

Thiolation of non-ionic surfactants for the development of lipid-based mucoadhesive drug delivery systems

The aim of this study was to develop thiolated self-emulsifying drug delivery systems (SEDDS) and nanostructured lipid carriers (NLCs) with improved mucoadhesive properties. Two non-ionic surfactants bearing a short and long PEG chain, namely polyoxyethylene (10) stearyl ether (PSE10) and polyoxyethylene (100) stearyl ether (PSE100), were thiolated for the first time by substituting the terminal hydroxyl group with a thiol group. The synthesis was confirmed by FT-IR, NMR and Ellman’s test. SEDDS and NLCs containing these thiolated compounds were investigated for size, polydispersity index (PDI) and ζ potential. Subsequently, mucus diffusion studies, rheological evaluations after mixing the nanocarriers with mucus and mucoadhesion studies on porcine intestinal mucosa were performed. All nanocarriers had a size less than 250 nm, a maximum PDI of 0.3 and a ζ potential < −9.0 mV. Mucus diffusion studies resulted in the rank order of increasing diffusivity: PSE10-SH < PSE100-SH < PSE10-OH < PSE100-OH for NLCs and PSE10-OH < PSE100-OH < PSE100-SH < PSE10-SH for SEDDS. The mucoadhesive properties and increase in viscosity of SEDDS and NLCs ranked: PSE100-OH < PSE10-OH < PSE100-SH < PSE10-SH. In addition, the short chain PSE10-SH showed higher mucus interactions than the long chain PSE100-SH for both SEDDS and NLCs. The thiolated PSE surfactants appeared to be promising excipients for the design of highly mucoadhesive drug delivery systems.

Natural Weathering Effects on the Mechanical, Rheological, and Morphological Properties of Magnetorheological Elastomer (MRE) in Tropical Climate.

Magnetorheological elastomer (MRE) materials have the potential to be used in a wide range of applications that require long-term service in hostile environments. These widespread applications will result in the emergence of MRE-specific durability issues, where durability refers to performance under in-service environmental conditions. In response, the outdoor tropical climatic environment, combined with the effects of weathering, will be the primary focus of this paper, specifically the photodegradation of the MRE. In this study, MRE made of silicone rubber (SR) and 70 wt% micron-sized carbonyl iron particles (CIP) were prepared and subjected to mechanical and rheological testing to evaluate the effects under natural weathering. Magnetorheological elastomer samples were exposed to the natural weathering conditions of a tropical climate in Kuala Lumpur, Malaysia, for 30 days. To obtain a comprehensive view of MRE degradation during natural weathering, mechanical testing, rheology, and morphological evaluation were all performed. The mechanical and rheological properties test results revealed that after 30 days of exposure and known meteorological parameters, Young’s modulus and storage modulus increased, while elongation at break decreased. The degradation processes of MRE during weathering, which are responsible for their undesirable change, were given special attention. With the help of morphological evidence, the relationship between these phenomena and the viscoelastic properties of MRE was comprehensively defined and discussed.

Essential oils nanoemulsion for the flavoring of functional stirred yogurt: Manufacturing, physicochemical, microbiological, and sensorial investigation

Stirred yogurt (SY) is preferred by different category of consumers due to its creamy mouthfeel and pourable texture, which make it an attractive dairy drink. In the current study, the authors developed a special SY which is naturally flavored using different essential oils nanoemulsions and functionalized using lactic acid bacteria. The particle size of the nanoemulsions was <30 nm for all utilized essential oils which included spearmint, lemongrass, clove and cinnamon. Three strains of lactic acid bacteria namely, L. helveticus , L. acidophilus and B. bifidum lactis were able to survive in the presence of the different nanoemulsions with bacterial count > 10 6 cfu/ml. Therefore, they were applied as supplements to the flavored SY during manufacture to enhance its functionality. The different rheological and physicochemical evaluations conducted on the developed SY indicates no effect of the EOs nanoemulsion on the general characteristics of SY along a storage period of 15 days. Overall sensory evaluation showed that all fresh EOs-flavored SY got highly preferred scores, however, at the end of storage period only lemongrass-flavored SY kept that score, while the other flavored samples were judged as preferred. The order of preference was lemongrass first followed by cinnamon, mint and clove. The article gives an insight on the application of EO nanoemulsions for developing naturally flavored functional dairy products especially stirred yogurt.

Rheological and Stability Evaluation of Emulsions Containing Fenugreek Galactomannan—Xanthan Gum Mixtures: Effect of Microwave and Ultrasound Treatments

The effects of treating two biopolymers (Trigonella foenum—graceum galactomannan and xanthan gum mixtures) with microwaves and ultrasound on the rheological aspects of O/W emulsions were investigated. The data obtained from steady shear flow were fitted with various models and the best were chosen due to the values of R2 and RMSE. The oscillatory shear rheology data demonstrated that the emulsions not treated with microwaves or ultrasound had viscous-like behavior and treated samples demonstrated weak gel behavior. The values obtained for various rheological parameters (especially apparent viscosity, storage modulus and loss modulus) indicated that fenugreek galactomannan had more impact on the rheological aspects of emulsions in comparison with xanthan gum. In addition, the synergistic interaction between two biopolymers, particularly in samples treated with ultrasound, resulted in better rheological aspects which could be affiliated with the strong bonds between the hydrocolloids. By treating the samples with microwaves and ultrasound, the emulsion stability values of the samples (especially those with a high ratio of galactomannan) significantly increased, which might be connected with various parameters, especially viscosity.

Rheological evaluation of wheat dough treated with ozone and ambient air during kneading and dough formation

SummaryThe aim of this study is to compare the application of ozone with that of air during the dough kneading process. Experiments were performed on doughs made from two wheat flours of different protein contents by changing the treatment time and oxidative gas. All samples were analyzed by Farinograph, oscillatory rheometer, and dough extensibility test. Farinograph measurements showed that water absorption capacity by ozone treatment during kneading was increased by 1.8% and 2.6%, and dough development time was 47% and 37% higher than of untreated doughs made of lower and higher quality wheat flour, respectively. Dough softening was reduced by 30% and 42% by air. Ozone treatment slightly decreased the dough stability of doughs made from higher quality flour and increased dough softening for both. Ozone treatment increased the force required to break the dough strand after 5 min by 42% and 23% for samples of lower and higher quality wheat flour, respectively. The extensibility of the dough behaved inversely. The frequency sweep test showed an increase in G′ and G″.

Effects of the oat β-glucan on the functional and structural properties of defatted walnut meal flour

The effects of oat β-glucan (OβG) with different concentrations (0–2.5%) on the functional and structural properties of walnut meal flour (WMF) were investigated. Fourier transform infrared (FTIR) analysis showed that the β-sheet content in WMF-OβG mixtures increased to 48.13%, while α-helix, random coil and β-turn decreased to 13.79%, 12.08% and 25.28%, respectively. Scanning electron microscopy (SEM) analysis exhibited that the surface structures of WMF and WMF-OβG mixtures were similar. Moreover, WMF-OβG mixtures presented a larger average particle size and a lower zeta-potential. Differential scanning calorimetry (DSC) result confirmed that the transition temperature of WMF-OβG mixtures was significantly higher than WFM, but the enthalpy was lower (p < 0.05). The rheological evaluation revealed that the OβG increased the storage modulus (G′), loss modulus (G′′) and viscosity of WMF. The WMF-OβG mixtures showed the higher foaming capacity, foaming stability and emulsion stability than that of WMF, while the emulsifying activity decreased. These findings suggest that OβG is an appropriate ingredient for modifying WMF functional properties, and can be potentially used in bakery, beverage and meat products.