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Structural and petrological evidence suggests an asymmetric and two-sided subduction of the Sistan oceanic lithosphere under the Lut and Afghan blocks. The subduction under the Lut block was characterized by a steeper dip angle and a higher subduction rate, leading to the retreat of the plate boundary towards the ocean and subsequent back-arc extension. Studies on the geochemistry and possible origin of the mafic-intermediate igneous rocks of the Lut block corroborate the occurrence of crustal thinning and back-arc extension, highlighting the significant role of subduction in their formation. In this research, we employed laboratory or analog modeling with scale lengths to simulate the characteristics of the Sistan oceanic lithosphere subduction and the geodynamic processes in eastern Iran. We investigated the parameters controlling the style of subduction by examining the sinking of a thin viscoelastic silicone putty sheet with varying geometric and rheological properties in a glucose syrup-filled reservoir. Our findings revealed that an increase in length and thickness, coupled with a low viscosity ratio of the lithosphere and asthenosphere, accelerates the subduction rate. We also identified a significant correlation between the dip angle and the subduction rate. In summary, the deformation of the back-arc region was analyzed through kinematic investigation in the performed experiments. The experimental outcomes, which confirm the high rate and dip angle of subduction, and also the back-arc extension, can be identified as characteristics of the Sistan Ocean's subduction zone under the Lut block. [ABSTRACT FROM AUTHOR]

One of the significant challenges in cementing operations is the ability to predict the rheological behavior of wellbore cement under bottom-hole conditions. Therefore, developing advanced fluid mechanics models is necessary to predict the rheological behavior of wellbore cement. This study focused on wellbore cement compositions in southern Iran's exploratory oilfields, considering time, temperature, pressure, and cement stability during drilling and production operations. The proper exploratory and development oil wells' cement formulation of the area shall be prepared according to the geological characteristics and static and circulation temperature at the beginning and end of the formation. It requires conducting various tests, such as compressive strength, free water, and thickening time, in the studied formations. Optimal compaction should be produced according to the amount of allowed slurry and comparing the data obtained from the tests. The values obtained from different formations were compared with those obtained from Bingham's plastic and power fluids theories, and the very low deviation of the shear stress calculated at different radii of the rotary viscometer was compared. It was concluded that Bingham's plastic model is the appropriate rheological model that describes the slurry's rheological properties, such as plastic viscosity, shear stress, shear rate, and density. The novelty aspects of this work include a rheology modeling error range of 0.11 to 0.95% for wellbore cement compositions and the accurate representation of these cement's rheological behavior. If this model is used to predict the rheological behavior of wellbore cement compositions before casing cementing, it can save drilling operations costs and time. It will also cause a correct evaluation of the reservoir layers and increase the production rate. [ABSTRACT FROM AUTHOR]

Background and Objectives: Clove essential oil is used due to its biological activity related to human health (antimicrobial and antioxidant) and flavoring application to enrich traditional aroushe cheese embedded in nanoencapsulation. Materials and Methods: Average particles size, polydispersity index and dynamic light scattering assessments were determined on nanoencapsulated clove essential oil (NCEO). Afterwards, the samples were fortified using Aroushe as a local cheese from Sangsar tribe in Semnan province, Iran, walnut powder (0, 1.9 and 3 % w/w) and NCEO (0, 0.3 and 0.6 % w/w), which physicochemical, rheology, microbial, sensory evaluation and microstructural characteristics were investigated during 40 days of shelf life in cold storage. Variance analysis was conducted for evaluation and the tests were performed in three repetitions. Results: NCEO caused a decline trend in pH feature due to phenolic acids and antioxidant components as well as the highest and lowest moisture levels were reported for control and Aroushe cheese with 3 % walnut and 0.6 % NCEO (AWC4) over 40 days. The most contents of fat and ash were obtained for AWC4 and Aroushe cheese with 3 % walnut and 0.3 % NCEO (AWC3 ) had the maximum protein. The microbial population was not distinguished in all treated samples on the 20th days of shelf life and AWC3 indicated the highest hardness, cohesiveness and springiness; nevertheless, AWC4 had the greatest adhesiveness. The maximum score was attained for AWC3 in overall acceptance of sensory evaluation and microstructure images prepared using a scanning electron microscopy exhibited that texture was uniform. Conclusions: As a result, AWC3 was an optimal selection for treated cheese sample and had the ability to apply as biofunctional natural products. [ABSTRACT FROM AUTHOR]

Lomashell, a mineral stone derived from oyster shells and skeletons, is widely available in Iran and across the globe. Typically used for livestock feed due to its high calcium content, its production generates a considerable amount of discarded fine grains. This research focused on incorporating micronized Lomashell as additive for asphalt pavement to enhance performance and environmental sustainability. The impact of this powder on the rheological and physical properties of two common asphalt binders was evaluated. Moisture resistance, rutting, and permanent deformation of Lomashell-enhanced asphalt mixtures were also examined. The results indicate significant improvements in rheological properties and dynamic shear rheometer parameters upon Lomashell addition. Moisture sensitivity was enhanced, as demonstrated by the indirect tensile strength test. Adding 7% of this material to the asphalt mixture enhanced indirect tensile strength by 12% compared to control. Furthermore, utilizing the Hamburg wheel-tracking device (HWTD), it was observed that inclusion of this powder enhanced resistance against permanent deformation, as evidenced by the rutting resistance index (RRD) values. Effective high-speed shear mixing is emphasized for binder modification, as revealed by scanning electron microscopy analysis. These findings highlight Lomashell's positive influence on the overall performance and durability of the asphalt mixtures, reducing rutting and enhancing resistance against permanent deformation. Utilizing this powder as asphalt additive holds promise for improving functionality and addressing environmental concerns, contributing to sustainable infrastructure development. [ABSTRACT FROM AUTHOR]

Bread is the main food in providing energy and protein in the diet of Iranian society. Therefore, the consumed bread must be of good quality, and one of the effective factors in its quality is the consumed flour gluten quality and quantity, which unfortunately, these factors are not desirable for wheat produced in Iran. One of the ways to decrease this problem is to use enzymes in the bread production flour. In this research, the effects of adding glucose oxidase (GO) and trans glutaminase (TG) enzymes in amounts of 0 to 30 ppm, α-amylase (AM) in amounts of 0 to 50 ppm and xylanase (XA) in amounts of 0 to 100 ppm on rheological properties of the Barbary and Lavash bread dough were prepared and analyzed using the response surface method (RSM) and the properties of the resulting dough were studied by farinograph, Falling number and alveograph rheological tests. The results of statistical analysis using Design Expert software showed that in different amounts of TG and GO, increasing AM caused a decrease in falling number. AM and XA decreased the amount of water absorption based on farinograph, but their interaction was not significant. At high amounts of AM and TG, farinograph index (FQC) was at its highest value. The increase of AM decreased the P index of the alveogram, whereas, the increase of GO and XA when used individually increased this parameter. The interaction effect of the last two enzymes was also significant and the median value of both which decreased P index. In Barbary and Lavash bread, the values of TG and GO in the maximum amounts (30 ppm) and AM in the values of 16 and 23 ppm were the most effective. The effect of XA enzyme was not significant in Barbary bread, but 23 ppm of XA showed a positive effect in Lavash bread. [ABSTRACT FROM AUTHOR]

Nowadays, conversion industries with the objective of reducing production costs in the country are of great importance. On one hand, considering the high amount of waste after poultry slaughter in Iran, on the other hand, there are a lot of evidences related to the beneficial effects of hyaluronic acid on human health, especially in the treatment of joint diseases such as osteoarthritis. Many efforts have been carried out to make the best usage of these wastes. Therefore, the purpose of this study was to obtain the hyaluronic acid from rooster comb tissue with suitable physicochemical and rheological properties to enrich various foods, including dairy products. In this research, after the initial preparation of rooster comb tissue, hyaluronic acid was extracted through three methods using ultrasound waves -ethanol, physiological serum - acetic acid and physiological serum -ethanol solvents. Then, the physicochemical and rheological attributes of the acquired hyaluronic acid were evaluated. Based on findings, the highest content of extracted hyaluronic acid (4.2 mg/g) was determined in the presence of physiological serum -ethanol solvents (P<0.05). Also, the hydrocolloid was extracted through the mentioned method, had the highest brightness (23.74) and the lowest pH (6.76) and density (810 kg/m³) (P<0.05). However, the influence of different extraction methods on viscosity was insignificant (P>0.05). Hence, the results of the present study showed that the physiological serum -ethanol are an appropriate solvents for extracting and purifying hyaluronic acid, which could be used as a functional food additive. [ABSTRACT FROM AUTHOR]

Cocoa milk is a popular milk -based drink, which its development can play a pivotal role in approaching the per capita dairy consumption in Iran. To sustain the product different stabilizers are used in the industry. The most common of which are carrageenan. Stabilizers are imported; therefore, they affect the finished product price.The main objective of this study was to investigate the effect of stability of acetyl starch with Kapa and Utah carrageenan on pasteurized cacao milk in terms of the characteristics of milk cacao and rheology. Initial experiments concentrating on physicochemical properties of samples which have different levels of starch, kappa, and carrageenan (sample 1 (Starch:50, Kappa carrageenan :23.982, Uta carrageenan:26.018) Sample 2 (Starch: 37.775, Kappa carrageenan : 26.456, Uta carrageenan : 35.769) Sample 3 (Starch: 36.189, Kappa carrageenan: 36.116, Uta carrageenan : 27.696) Sample 4 ( Starch: 35.221, kappa carrageenan : 38.206, Uta carrageenan : 26.572)) have been done. Initial tests of cacao milk including PH, acidity, and fatty dry matter measurements as well as sensory evaluation on all samples have been carried out. A preliminary analysis of stability and sedimentation was performed using centrifuge. According to the results, 4 samples were selected with better sensory and physicochemical properties among 28 treatments and Rheological tests were performed on these specimens. To better examining the results Hustler -Balkillian, Ostwald and Bingham models were used. Herschel - Bulkley's model has better adjustment with the results. Finally, according to the results of rheology, a sample with a higher starch content was selected which contains 50% of starch in its stabilizing composition. [ABSTRACT FROM AUTHOR]

Nowadays, hydrocolloids, especially galactomannans, are applied as thickening agents in food and pharmaceutical products. Gleditsia caspica, known as Persian honey locust, which is available in large quantities in the northern regions of Iran, is found to be rich in galactomannan. To better investigate the thickening properties, a complete research on the rheological features of galactomannan with different concentrations in aqueous solutions is of particular importance. The obtained results of steady shear flow experiments indicated that the stress–shear rate, apparent viscosity–shear rate, and stress-time data were well fitted with power law, Cross and Figuni–Shoemaker models according to their R2 and RMSE values. Strain and frequency sweep experiment consequences demonstrated that the solutions containing 0.5 and 1% w/v galactomannan exhibited viscous-like behavior that is mainly associated with lack of strong interactions in the conformation and solutions containing 1.5% w/v galactomannan indicated gel-like behavior that is affiliated with more stable interactions between chains in the conformation. Intrinsic viscosity of obtained galactomannan was in the range of 6.7282–7.1722 dl/g. [ABSTRACT FROM AUTHOR]

Introduction. Berberis vulgaris is a native plant in Iran and the seedless type gained a reputation for the southern regions of Khorasan. The effect of adding mixture of basil seed gumcarrageenan and xanthan-carrageenan gum on rheological behavior and stability of suspended barberry pulp in syrup was investigated. Materials and methods. Sugar 4.8% (w/v), glucose syrup 21%(w/v), barberry concentrate 17%(w/v), water 54%(w/v), and barberry pulps2%(w/v) were weighed. Different ratios of hydrocolloids (1.20%(w/v)), including basil seed gumcarrageenan and xanthan-carrageenan were prepared. The gum solution and other ingredients were heated to 60 ºC for 10 minutes. To prepare the final product, the pulps of barberry were directly added to the solution. Rheological and sensory properties were evaluated. Results and discussion. The highest apparent viscosity belonged to sample with 100% basil seed gum, and the lowest value was for the sample containing 100% carrageenan. Samples containing xanthan-carrageenan had lower apparent viscosity compared to sample with basil seed gum-carrageenan. Increasing the amount of basil seed gum by formation of a three-dimensional network of continuous phase increases viscosity and make suitable conditions for suspending barberry pulp. It was found that the most suitable model for predicting the flow behavior of the samples was the Herschel-Bulkley model. Samples containing 70% basil seed gum and 30% carrageenan, due to the proper appearance and appropriate suspension of barberry particles, gained the highest scores in terms of sensory properties by the panelists and the lowest scores belonged to the sample containing 100% xanthan gum. The samples containing 100% basil seed gum and 100% xanthan gum showed the highest density and the lowest density, respectively. Conclusions. According to the results obtained the sample containing 70% basil seed gum and 30% carrageenan showed the highest score in terms of sensory properties, stability and suspension assessment compared to other sample and could be introduced as a suitable formulation of barberry suspended pulp in the syrup. [ABSTRACT FROM AUTHOR]

The 300 km long arc of the Fars province is located to the south east of the NW-SE trending and SW vergent orogen of the Zagros Mountains. This region is one of the largest hydrocarbon reserves worldwide, and also as a territory of high quality outcrops. Geological cross-sections of the Zagros belt are usually based on very large scale geological maps (1:1.000.000 or 1:250.000), and on few subsurface data and aim at describing the decoupling relationship between cover and basement rocks and the subduction/collision history of the Arabian – Eurasia plates. In this paper, we present a 253 km long cross-section across the Fars province on the basis of detailed geological maps (1:100.000 scale), field and subsurface data. Our purposes are to: 1) investigate the link between shortening inferred from our original cross-section (from a maximum of 9,1% to a minimum of 4,4%. for different sectors of the belt) and rift-related and flexure-related extensional faults, which in turn, control thickness and lateral facies variations; 2) describe the geometries of folds and thrusts and their relationship with pre-thrusting normal faults, that were inverted during shortening as transpressional or strike slip faults. Moreover, we present for the first time new field data showing evidences of syn-collisional normal faults likely related to the bending of the Arabian plate in the Fars area. [ABSTRACT FROM AUTHOR]

Careful design and preparation of drilling fluids with appropriate rheology and filtration properties, combined with operational monitoring, is essential for successful drilling operations. Field results reveal that most drilling-fluid problems encountered are avoidable based on prompt detection of unexpected changes in fluid rheology and filtration behavior. Drilling-fluid rheology and filtration properties are typically only checked once or twice a day, whereas other drilling-fluid properties, such as fluid density (FD), solid percentage (S%), and March funnel viscosity (MFV), tend to be monitored several times per hour. Machine learning is therefore applied to estimate rheology and filtration properties with FD, S%, and MFV as input variables. A 1160-record field dataset collected from 14 wells drilled in two oil and gas fields in southwest Iran with water-based drilling fluids is used to predict the drilling fluid's rheological and filtration characteristics. Plastic viscosity (PV), yield point (YP), and filtrate volume (FV) are the targeted prediction objectives. Of six models tested, Multilayer extreme learning machine (MELM) hybridized with the cuckoo optimization algorithm (COA) provides the best PV, YP, and FV predictions. It achieves root mean squared error (RMSE) values of 0.6357 mL (FV), 0.6086 cP (PV), and 0.6796 lb/100 ft 2 (YP). MELM-COA generates rapid and accurate estimations of rheology and filtration properties with potential for real-time monitoring during drilling operations, without recourse to time-consuming laboratory filtration and rheological tests. This work delivers, in a novel way, accurate and reliable predictions of drilling fluid filtration properties using only the more readily available FD, MFV, and S% variables as input features. • Hybrid machine learning (HML) models key water-based drilling-fluid (WBFs) properties. • Novel HML model configurations deliver precise WBF filtration predictions. • Fast and accurate predictions of plastic viscosity and yield point delivered in real time. • Cuckoo optimization algorithm (COA) provides the most effective HML control values. • Multi-layered extreme learning machine with COA provides the most accurate predictions. [ABSTRACT FROM AUTHOR]

Postseismic deformation is one of the few geophysical phenomena that can be used to obtain the rheological properties of the lithosphere and provide key information for understanding stress variations that are induced by the mainshock or aftershock. On November 12, 2017, the Mw 7.3 Darbandikhan earthquake struck the border between Iran and Iraq, causing heavy casualties and property losses. Here, we first use the multidimensional small baseline subset technique to obtain the 2D postseismic deformation field from Interferometric Synthetic Aperture Radar data within ∼228 days after the event. The 2D postseismic deformation field shows that the main deformation region exhibits westwards horizontal movement with a maximum displacement of 7.5 cm, while the maximum uplift and subsidence reach 8.2 cm and 4.7 cm in the southwestern and northeastern areas of the main deformation region, respectively. Then, we choose preferred faults of co- and post-seismic slip distributions by considering the distribution of co- and post-seismic slip, aftershock precision location results, data misfits, and the Coulomb failure stress change from previous studies and use a joint model to simultaneously estimate the afterslip distribution and viscosity of the lower crust in the Zagros Mountains. As a result, the joint inversion performed on the flat-ramp-flat fault (preferred fault) suggests that the lower bound of the preferred viscosity of the lower crust beneath the Zagros Mountains is 3 × 1018 Pa s, the afterslip is distributed both up- and down-dip of the coseismic slip region, and the maximum slip of 0.61 m is located up-dip of the coseismic rupture. The cumulative seismic moment caused by the afterslip is 2.97 × 1019 N m, which is equivalent to a Mw 6.94 earthquake. Moreover, the stability and reliability of faults and the joint model are verified through Monte Carlo inversions. • we use the multi-dimensional small baseline subset technique to obtain the 2 D post-seismic deformation field from InSAR data within ∼228 days after the event. • the listric fault and flat-ramp-flat fault are regard as the preferred faults of co- and post-seismic slip distributions. • we use a joint model to simultaneously estimate the afterslip distribution and the viscosity of the lower crust in the Zagros Mountains. [ABSTRACT FROM AUTHOR]

In this research, seeds of Iranian carob trees grown wild in Kazeroon city (Fars Province) were used to extract Iranian locust bean gum as a seed galactomannan. Chemical composition, solubility, and rheological properties of crude and purified gums were investigated and compared with a commercial (Sigma) locust bean gum (LBG) sample. Chemical composition of the purified Iranian LBG was similar to the commercial LBG, however, the protein content of Iranian crude LBG was higher. Solubility data showed that the Iranian crude LBG was partially cold-water soluble (∼ 55% at 25°C) and needed heating to reach a higher solubility value (∼ 71% at 80 °C). Rheological properties of the solutions of the three LBG samples were investigated as a function of concentration and temperature (5-60 °C) at shear rate range of 0.5-200 s-1. All three samples showed shear thinning behavior and Power law model was used to fit the experimental data. The Iranian LBG (crude and pure) was able to thicken aqueous solutions; however, its viscosity level was lower than that of the commercial LBG. Study of rheological properties of the three LBG samples at different pH levels (2.5-10) showed that they were significantly affected by pH. The intrinsic viscosities of the Iranian crude and purified LBG and commercial LBG were 3.95, 9.05, and 9.48 dL g-1, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Doogh is a fermented dairy drink which is highly consumed by Iranian people. Stability of this healthy drink was investigated in terms of sedimentation rate, viscosity, density and particle size characteristics including surface-weighted mean diameter (D 32), Span and particle uniformity. Eight treatments were performed as randomized complete block design (RCBD) with three replications. Three types of pectin (high methoxyl pectin (HMP), grapefruit-seed extract pectin (GSEP) and amidated pectin (Ceamsa pectin (CSP)) at a constant concentration (0.35%w/w), three levels of salt (0.50, 0.75 and 1.00%w/w) and two dry matter contents (DMCs, 4 and 5% w/w) were used to produce the Dooghs. The results showed that the maximum stability and viscosity, and the minimum D 32 were obtained by application of CSP, GSEP and HMP, respectively (p <0.05). Pectin type had no significant difference on the density values of Dooghs. The lowest sedimentation rate, viscosity, density and D 32 were achieved in the minimum concentrations of salt and dry matter. The ANOVA analysis also revealed that the interaction of pectin type, salt concentration and DMC had a significant effect on the Span and particle uniformity. A maximum physical stability was found for the prepared samples with 0.35%w/w CSP, 0.5%w/w salt and 4%w/w dry matter. Evaluation of sensory attributes also confirmed that this formulation had the highest overall acceptability value. [Copyright &y& Elsevier]

Abstract: The effects of various concentrations of three species of gum tragacanth on the gelation process, microstructure and viscoelastic properties of milk protein mixed gels acidified at 37°C by glucono-δ-lactone (GDL) were investigated using dynamic rheometry and microscopy. According to rheological measurements, the addition of gum tragacanth in the range of 0.05–0.2% (w/w) into milk protein dispersions led to a weaker structure for the milk protein network, compared to the control sample. This weakening effect could be eliminated by adding 0.3% (w/w) gum tragacanth exudates from A. gossypinus; the compositional features of gum tragacanth may have been responsible for the improved protein–protein interactions, greater structural strength and reduced gelation time onset. It was determined by scanning electron microscopy that the addition of gum tragacanth at a low concentration caused the density of the matrix to increase, while an open structure was observed in the presence of a higher gum concentration. [Copyright &y& Elsevier]

Abstract: We used a combination of broad ion beam cross-sectioning and cryogenic SEM to image polished surfaces and corresponding pairs of fractured grain boundaries in an investigation of grain boundary microstructures and fluid distribution in naturally deformed halite from the Qom Kuh salt glacier (central Iran). At the scale of observations, four types of fluid-filled grain boundary can be distinguished by morphology (from straight to wavy), thickness (from 5000 to 50 nm) and the presence of fluid inclusions. The mobility of the brine is shown after cutting the inclusions by broad ion beam (BIB) in vacuum and fine-grained halite forms efflorescence and precipitates on internal walls of inclusions. At cryogenic temperature, grain boundary brine is shown either as continuous film or in isolated inclusions. The halite–halite grain boundary between isolated fluid inclusions is interpreted to have formed by fluid-assisted grain boundary healing. Preliminary experiments on the samples at shear stress conditions of natural salt glacier show very slow strain rates (7.4 × 10−10 s−1 and 1 × 10−9 s−1), which are less than expected for pressure solution creep. Both microstructures and deformation experiments suggest interfacial energy-driven grain boundary healing and therefore rendering inactive the pressure solution creep in our samples. This result disagrees with previous microstructural studies of the same sample, which showed microstructural evidence for pressure solution (and dislocation creep). Different explanations are discussed, which imply that both healing and reactivation of grain boundaries are important in salt glaciers, leading to heterogeneous distribution of deformation mechanisms and strain rates in both space and time. [Copyright &y& Elsevier]

Abstract: A three-dimensional lithosphere model with horizontal dimensions of 1500km×600km and a depth extent of 70km is constructed from available geophysical data to find out strength (as the maximum deviatoric stress the lithosphere supports at a given depth) in Arabia–Eurasia plate boundary zone. The constructed model is first used in the calculation of thermal initial condition and then strength envelopes were calculated using the obtained geotherm and rheological flow laws. Numerical models are run for initial temperature distributions representing cold and hot lithosphere with two different rheology (wet and dry). The obtained mechanical structures were analyzed and compared with other geophysical data; e.g., seismicity-depth and isotherm-depth distributions. Model results for wet and dry rheology indicate that the depth of the brittle–ductile transition is about 8km and 11km for hot geotherm and 10.5km to14km and 21–28 for cold geotherm. The results are in good agreement with focal depth in the Zagros that most earthquakes occur in 8–15km depth i.e. the long-term strength of the continental lithosphere resided only in its upper part, which was contained wholly within the crust. The ILSs (integrated lithospheric strengths) values for a wet crustal rheology have high range of 1.4–10×1012 Nm−1, which is mainly the result of a low heat-flow (cold geotherm) and 0.1×1012 Nm−1 for wet rheology and hot geotherm. [Copyright &y& Elsevier]

Fractured and complex formations where types of fractured and porous mud loss occurred in commonly induced instability of wellbore and drilling accidents such as borehole collapse and blowout; therefore, it is the technological bottleneck for the development of oil and gas. Solid free recyclable foam drilling fluid was developed and aimed to deal with the MIS oilfield of Iran, which has abnormally low pressure and developed fracture-cave hydrocarbon reservoir with a high concentration of H2S, which has problems such as serious lost circulation and H2S risk. A sectionalized drilling fluid system has been adopted in this oilfield, and drilling with water can meet the operation requirements during first spud and saturated salt polymer system or undersaturated salt polymer in second spud; the horizontal section adopts solid free recyclable foam drilling fluid to achieve near balance drilling and effectively solves the lost circulation problem in fractured limestone formation. The spot application indicates that solid free recyclable foam drilling fluid has excellent rheology, and meets the requirement of drilling engineering. Meanwhile, the system can retard the H2S corrosion effect on drillstring and guarantee to provide a good MWD transmission signal. A new idea has been provided for drilling engineering in fractured and complex formations. [ABSTRACT FROM AUTHOR]

This article has experimentally investigated and modeled the influence of variables such as hole angle, fluid rheology, cuttings size, circulation rate, and annular size on cuttings transport velocity using the concept of minimum transport velocity (MTV). The proposed method was checked against field values and has produced excellent results. The results obtained from this model were compared with Larsen's (1997) model and insignificant differences were observed. The result shows that this work can be utilized as a superior tool in drilling of directional and horizontal wells in Iran. [ABSTRACT FROM AUTHOR]

Barite sag is an oilfield term used to describe significant density variations while circulating bottoms up after a trip, logging run, or other operation that requires the mud to remain static for an extended period of time. Sag is caused by static or dynamic settling followed by slumping of the weighted material. Static sag, as the name suggests, is caused when circulating is stopped for an extended period of time, and the weighting agents begin to settle under the influence of gravity. Due to slumping, dynamic sag occurs frequently in inclined holes. However, the problem has been exacerbated by the increased frequently of high-angle wells with the associated increase in particle settling rate, which occurs in an inclined fluid column. The settling of solids is enhanced by convective currents created by density differences in the fluid across the annulus cross-section. This effect is frequently referred to as the Boycott effect. The authors present the most effective ways to avoid the occurrence of barite sag in high-pressure high-temperature drilling operations, and in high-angle wells beside a case study in Gachsaran formation in the Ahwaz oil field of Iran. The methods include replacing barite with other weighted materials such as ilmenite or manganese tetraoxide. The lower the Equivalent Circulating Density, the higher the rate of drilling operation as well as the lower pressure losses especially in mud pumps. The authors introduce a new water-based mud formulation that uses attapulgite and xanthan gum as viscosifiers. By using a Brookfield viscometer (DV-II + Pro), viscosities of different muds at ultralow shear rates were measured. According to their rheological properties, a desirable mud formulation was developed. [ABSTRACT FROM AUTHOR]

Thin-skinned fold-and-thrust belts are generally considered as the result of contractional deformation of a sedimentary succession over a weak décollement layer. The resulting surface expression frequently consists of anticlines and synclines spaced in a fairly regular manner. It is thus tempting to use this spacing along with other geological constraints to obtain insights into the dynamics and rheology of the crust on geological time scales. Here we use the Zagros Mountains of Iran as a case study, as it is one of the most spectacular, well-studied thin-skinned fold-and- thrust belts in the world. Both analytical and numerical models are employed to study what controls fold spacing and under what conditions folding dominates over thrusting. The models show that if only a single basal décollement layer is present underneath a brittle sedimentary cover, deformation is dominated by thrusting, which is inconsistent with the data of the Zagros fold belt. If we instead take into account additional décollement layers that have been documented in the field, a switch in deformation mode occurs and crustal-scale folding is obtained with the correct spacing and time scales. We show that fold spacing can be used to constrain the friction angle of the crust, which is ~5° in the Zagros fold belt. This implies that on geological time scales, the upper crust is significantly weaker than previously thought, possibly due to the effect of fluids. [ABSTRACT FROM AUTHOR]

Flow improvers are used extensively to increase the mobility of crude oil. This article deals with the relation between the rheological properties and solubility parameter of flow improvers in different solvents. Two types of Iranian waxy crude oils with different pour points were selected. The rheological behavior of this crude oil in the presence and absence of flow improvers in different solvents was measured. The rheological data cover the temperature range of 5°C to 40°C. Results show that the shear rate has an appreciable effect in decreasing viscosity, particularly at temperatures below the pour point. Poly ethylene-vinyl acetate copolymer (EVA) as flow improver with different range of molecular weights was used for the treatment of waxy crude oil. The results indicated that the performance of flow improvers was dependent on the molecular weight, type of solvent, and the type of crude oil. The phase behavior of EVA copolymers was investigated in various solvents. The flow improver in the poor solvent (cyclohexane) gave better results in improving the flowability of the crude oil, compared with the other solvent. [ABSTRACT FROM AUTHOR]

Viscoelastic behaviour of some commercial sweet cherry cultivars of Iran has been studied in current research. For this purpose, stress relaxation test was conducted on five cultivars of sweet cherry including Siah Mashhad, Abarde, Victoria, Dovom Ras and Tak Dane. Two common models (Generalised Maxwell model and Peleg model) were fitted to the experimental data. Both models could describe stress relaxation behaviour of cherries ( R = 0.99), but Generalised Maxwell model had lower root mean square error (RMSE) than Peleg model. Based on analysis of stress relaxation data using models constants, Tak Dane exhibited more solid properties, while Victoria showed less elastic behaviour than other cultivars. The results revealed that relaxation ratio ( R%) and the area under the stress relaxation curve could be effective alternative to models with easier mathematical procedure. [ABSTRACT FROM AUTHOR]

Abstract: Doogh is a traditional Iranian drink prepared by fragmentation and dilution of yogurt, with addition of salt and flavouring. In the present work, we have used viscometry, microscopy, particle-size analysis and measurements of serum separation to explore the effect of very low concentrations of gellan gum (0.01, 0.03 and 0.05wt %), alone or in combination with 0.25wt % high-methoxy pectin (HMP), on its structure and stability. HMP is known to prevent association of casein particles in acidic milk drinks by steric stabilisation, forming a protective layer bound electrostatically to the surface of the particles. Doogh incorporating 0.25wt % HMP alone showed satisfactory stability on storage for ∼10 days at 5°C, but after 15 days there was obvious separation into a dense sediment and a much clearer upper layer that occupied more than 80% of the total volume, which we attribute to progressive sedimentation of individual sterically-stabilised particles. Samples incorporating gellan (with or without HMP), by contrast, showed rapid development of a clear serum phase, with little further separation at longer times (up to ∼1 month), suggesting expression of fluid by contraction of a gel network (i.e. syneresis rather than sedimentation). Particle size increased dramatically (more than 10-fold) with increasing concentration of gellan, and at the highest concentration studied (0.05wt %) a continuous network of casein-rich strands was observed by phase-contrast microscopy. The concentration of NaCl used in the doogh samples (0.5wt %≈85mM) is known to be sufficient to maintain gellan in its ordered (double-helix) conformation, which has higher charge density than individual molecules of HMP. We suggest that network structure is formed by electrostatic attachment of gellan to fragments of acid-casein gel, thus increasing particle size and inhibiting surface-coverage by HMP, with weaker associations between gellan helices allowing the samples to flow. Observed decrease in serum volume with increasing concentration of gellan is attributed to formation of progressively stronger coupled networks with greater resistance to syneresis. Stabilisation of doogh with 0.05wt % gellan in combination with 0.25wt % HMP had no adverse effect on organoleptic acceptability, and reduced serum volume on protracted storage to ∼10% (in comparison with over 80% for the same concentration of HMP alone), suggesting that gellan could be of practical value in extending the shelf-life of doogh (and related acidic milk drinks). [Copyright &y& Elsevier]

In this study, the physicochemical properties and rheological behavior of a number of tomato pastes manufactured by Iranian food processors were compared. Chemical composition tests, color measurement, consistency and rotational viscometry were performed. There were significant differences among the samples in terms of Brix, salt level, vitamin C and Hunter color parameters (L and a/b). Some of the parameters did not pass the standard requirements set by the Institute of Standards and Industrial Research of Iran (ISIRI), e.g. Brix, color and salt. The rotational viscometry tests and shear stress–shear rate curves at 30, 45 and 60_C indicated the existence of variations among the samples in terms of apparent viscosity and yield stress. All tomato paste samples in this study were non-Newtonian fluids and the apparent viscosity of the pastes decreased with temperature increase. The rheological data obtained were fitted using a Power Law equation. The differences were attributed to raw material variations and processing conditions. [ABSTRACT FROM AUTHOR]

Basil seed ( Ocimum basilicum L.) is cultivated in large quantities in different regions of Iran. This seed has reasonable amounts of gum with good functional properties which is comparable with commercial food hydrocolloids. A central composite rotatable design was applied to evaluate the effects of temperature, pH and water/seed ratio on the yield, apparent viscosity and protein content of water-extracted Basil seed gum. All of the variables significantly ( P < 0.05) affected the extraction yield, whereas the effect of water/seed ratio on apparent viscosity and the effects of pH and water/seed ratio on protein content were not significant ( P > 0.05). Numerical optimisation determined the optimum extraction conditions based on the highest yield and viscosity and the lowest protein content as being temperature 68.71 °C, pH 8.09 and water/seed ratio 65.98:1. Power law model well described non-Newtonian pseudoplastic behaviour of BSG. Flow behaviour index ( n) and consistency index ( K) of 1% crude and pure BSG samples were 0.306, 0.283 and 17.46, 20.22 Pa s n, respectively. [ABSTRACT FROM AUTHOR]

Saline-sodic soils are susceptible to wind and water erosion when the dispersive effect of sodium overcomes inter-particle bonds. Rheological parameters of viscoelasticity can help to quantify inter-particle attractive forces and account for the effect of salinity in these soils. The main objective of the present study was to investigate the viscoelasticity behavior of saline-sodic soils of the Sirjan playa in south-central Iran. Three representative pedons were excavated and described by horizon. Soil physicochemical properties and rheological properties were determined, namely the micromechanical parameters flow point (γ f), loss factor tan δ, and integral z , with samples analyzed at three matric potentials (0, −6, and −15 kPa). Results showed that soil microstructural stiffness was mainly influenced by soil texture, clay minerals, gypsum, calcium carbonate equivalent (CCE), and matric potential. The dispersive effect of sodium, as indicated by low integral z and γ f values, decreased with increasing gypsum content in − 6 and − 15 kPa matric potentials (0.6 < r < 0.8) and CCE percentage in the quasi-saturated (0 kPa) condition (r > 0.8). However, greater microstructural stability (i.e., higher integral z and γ f) was observed for fine-textured soils with relatively high amounts of smectite and palygorskite and low pH. Furthermore, integral z and γ f increased with lower matric potentials due to the stabilizing effect of menisci forces. Therefore, the viscoelastic behavior of the saline-sodic soils was negatively associated with water content and high sodium concentration, while the presence of smectite, palygorskite, gypsum, and CCE improved the soil physical conditions and thus the rigidity of the porous system. These results demonstrate that rheological measurements can identify saline-sodic soils that have strongly degraded microstructural stability and would most benefit from active management and amelioration. • Microstructural stability of saline-sodic soils in Sirjan Playa were analyzed via rheometry. • Sodium content had negative, non-significantly correlation with microstructural stability. • Smectite, palygosrkite, gypsum, and calcium carbonates increased microstructural stability. • Samples with negative matric potentials increased microstructural stability similarly. • Soil texture, mineralogy, and counterion concentrations may also translate to mesoscale considerations of erosion assessment. [ABSTRACT FROM AUTHOR]

Abstract: The frequency sweep test was used to evaluate storage modulus (G′), loss modulus (G′′) and loss tangent [tan (δ)] of Iranian UF-Feta cheese during ripening period (3, 20, 40 and 60 days). With development of ripening, storage and loss moduli increased at varying rates. The rate of increase in G′ was greater than that in G′′ resulting in a reduction in tan (δ). That is, storage modulus was dominant to loss modulus and as a result the elasticity nature was greater than the viscous nature of cheese samples. Due to the disruption of fat globules and proteolysis, protein matrix rearranged and formed a more compact texture containing aggregates of casein. Ripening did not influence the pH level and also the concentrations of dry matter, fat, salt, and total nitrogen in dry matter. However, water soluble nitrogen increased significantly (P <0.05). [Copyright &y& Elsevier]

• Rheological and physicochemical properties were measured in a hillslope catena. • Rheometry showed that Alfisol and Mollisol pedons had high microstructural stability. • Entisol had lowest rheological parameter values, likely due to weak soil development. • Integral z parameter correlated with aluminum and iron sesquioxide concentrations. • Rheological parameters are useful to quantify microaggregate structure and stability. Rheological characteristics of soils, including their deformation and flow behaviors when subjected to external stress, can provide important information on microstructural stability. In this study we used rheological measurements to examine the soil aggregate microstructure and stability of four different soil orders – Alfisol, Mollisol, Inceptisol, and Entisol – along a forested catena in Mazandaran Province, northern Iran. Amplitude sweep tests were used to quantify the initial values of the storage and loss moduli, deformation limit (when the material begins to transition from reversible to irreversible deformation), deformation at flow point (when the material becomes viscous), and integral z (which summarizes the overall visco-elasticity of the material). The deformation limit was significantly higher in subsoil layers than topsoil layers, and was also higher in the Mollisol than the other pedons. The flow point and integral z values, which relate to the structural stiffness of soil matrices, were largest in the Btg horizons of the Alfisol and Mollisol, implying that these soils had more rigid microstructures. In contrast, the Entisol Ckg horizon, which had high sand content and little soil development, had the lowest values for all properties, thus indicating a lack of micro-aggregate stability. Regression analyses revealed that integral z was influenced by soil physicochemical properties, and was higher in soils whose clay fraction was dominated by expansive clay minerals and pedogenic iron and aluminum sesquioxides. Altogether, the rheological parameters indicated that older, more developed soils had greater microstructural stability than their less developed counterparts. As a result, rheological measurements may be useful for identifying the major factors that affect soil aggregation, and can indicate the relative amount of soil development along gradients such as the studied forest catena. [ABSTRACT FROM AUTHOR]

Abstract: Major compositional components and rheological behavior as a function of concentration and temperature for two current types of salep (palmate- and rounded-tuber) in Iran were investigated. Palmate-tuber salep (PTS) was richer in glucomannan content (58.22% versus 22.13% w/w) but lower in starch content (1.67% versus 6.15% w/w) than the rounded-tuber salep (RTS). A clearly pseudoplastic behavior was observed at all concentrations (2%, 3%, 4%, 5% for PTS, and 4%, 5%, 6%, 7% for RTS) and temperatures (5, 25, 45 and 65°C) for each two salep types. The power law model well described the rheological behavior of the salep solutions with high determination coefficients, r 2. An increase in concentration was accompanied with an increase in pseudoplasticity, n, and consistency index, k. As temperature increased, the salep solutions showed a lower consistency and were tending to be closer to Newtonian flow (the n-values nearer to 1). At similar concentrations and temperatures, the PTSs created solutions with more pseudoplasticity and consistency than the RTSs. This was attributed to their different chemical composition, mainly glucomannan and starch contents. Temperature dependency of the consistency index for the salep solutions was successfully described by the Arrhenius model with high r 2 values. The activation energy, E a, for the PTS decreased from 36.356kJ/mole at 2% concentration to 22.746kJ/mole at 5% concentration. For the RTS, the activation energy decreased from 29.628kJ/mole at 4% concentration to 25.430kJ/mole at 7% concentration. In contrast, the frequency factors, A, increased as the concentration increased. [Copyright &y& Elsevier]

Abstract: The present day morphology of the Zagros fold-thrust belt is dominated by magnificent exposures of NW–SE trending folds. These folds differ in their size and geometry and these differences are related mainly to the rheological profile of the cover rock. The cover rock succession of the Zagros consists of a sequence of competent and incompetent units which vary both along and across the belt. Field based study combined with the use of satellite images reveals that the thickness and facies distribution of the cover rock succession has a significant impact on the style of deformation. During the shortening linked to the current convergence of the Arabian and Iranian plates, the incompetent units act as detachment horizons which localise thrusting and which act as décollement above which detachment folds form. In addition, where these incompetent units are thick (e.g.>1 km), they allow the deformation above and below them to become completely decoupled enabling disharmonic folding to occur. As a result the folds above and below the incompetent units in the central part of the Zagros Folded Belt, have significantly different geometries and wavelengths. As the Zagros folds host the majority of the hydrocarbon reserves in Iran and Iraq, an understanding of the processes that influence their geometry and spatial organization at different levels in the cover rock is crucial for the future exploration in the region. [Copyright &y& Elsevier]

The interaction of the Arabian plate with the Eurasian plate has played a major role in building the young mountain belts along the Zagros–Bitlis continent–continent collision zone. Arabia's northward motion is considered to be the primary driving force behind the present-day westerly escape of the Anatolian plate along the North and East Anatolian fault zones as well as the formation of the Turkish and the Iranian plateaux. In this study we mapped Pn-wave velocity and anisotropy structures at the junction of the Arabian, Eurasian and African plates in order to elucidate the upper-mantle dynamics in this region. Pn is a wave that propagates within the mantle lid of the lithosphere and is often used to infer the rheology and fabric of the mantle lithosphere. Applying strict selection criteria, we used arrival times of 166 000 Pn phases to invert for velocity and anisotropy in the region. Using a least-squares tomographic code, these data were analysed to solve simultaneously for both velocity and azimuthal anisotropy in the mantle lithosphere. We found that most of the continental regions in our study area are underlain by low Pn velocity structures. Broad-scale (∼500 km) zones of low (<8 km s−1) Pn velocity anomalies underlie the Anatolian plate, the Anatolian plateau, the Caucasus region, northwestern Iran and northwestern Arabia, and smaller scale (∼200 km), very low (<7.8 km s−1) Pn velocity zones underlie southern Syria, the Lesser Caucasus, the Isparta Angle, central Turkey and the northern Aegean Sea. The broad-scale low-velocity regions are interpreted to be hot and unstable mantle lid zones, whereas very low Pn velocity zones are interpreted to be regions of no mantle lid. The low and very low Pn velocity zones in eastern Turkey, northwestern Iran and the Caucasus region may be associated with the latest stage of intense volcanism that has been active since the Late Miocene. The low Pn velocity zones beneath the Anatolian plate, eastern Turkey and northwestern Iran may in part be a result of the subducted Tethyan oceanic lithosphere beneath Eurasia. We also found a major low-velocity zone beneath northwestern Arabia and the Dead Sea fault system. We interpret this anomaly to be a possible extension of the hot and anomalous upper mantle of the Red Sea and East Africa rift system. High Pn velocities (8.1–8.4 km s−1) are observed to underlie the Mediterranean Sea, the Black Sea, the Caspian Sea, and the central and eastern Arabian plate. Observed Pn anisotropy showed a higher degree of lateral variation than did the Pn velocity structure. Although the Pn anisotropy varies even in a given tectonic region, in eastern Anatolia very low Pn velocity and Pn anisotropy structures appear to be coherent. [ABSTRACT FROM AUTHOR]

Persian gum as a newly introduced source of carbohydrate polymers obtained from the trunk and branches of wild almond trees of Zagros forests in Iran, has found wide applications in food and pharmaceutical industry owing to its unique structure. However, its behavior in soil environment is still unknown. This paper proposes application of Persian gum to stabilization process of a low plasticity clayey soil. A series of macro and micro scale tests including unconfined compression strength, direct shear test, scanning electron microscopy imaging, Stereo zoom microscopy, Brunauer, Emmett and Teller tests, thermal gravimetric analysis and Particle size analysis were conducted on soil stabilized with different amounts of Persian gum. All defined tests were also conducted on previously studied soil additives, xanthan and guar gums. The results confirm the successful performance of Persian gum in binding soil particles, pore filling, thermal stability, soil fluctuation and formation of large particles in comparison to common hydrocolloids., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The development of a novel snack bar based on sesame paste (SP) and date syrup (DS) was investigated. The aim of this study was to evaluation the effects of SP/DS ratio and encapsulated thymol (thymol-loaded nanostructured lipid carrier [TNLC]) on physicochemical, textural, rheological, and sensorial properties of snack bars. The effect of butylated hydroxytoluene (BHT), thymol, and TNLC showed that the addition of 100 ppm TNLC could improve the oxidative stability of SP/DS mixtures even better than BHT, while a higher concentration of TNLC had a negative effect. The unpleasant taste and odor of thymol could be overcome by its encapsulation in nanostructured lipid carriers. The textural properties of the formulations with different SP/DS ratios (1:2, 1:1, 2:1) and an overall concentration of 7 g of gelatin/kg of mixtures were evaluated. The texture profile analysis showed that the sample with an SP/DS ratio of 1:1 had higher hardness, adhesiveness, springiness, cohesiveness, and gumminess in comparison with the other ratios. From the sensory evaluation data, the bar prepared with an SP/DS ratio of 1:1 had the most acceptable texture. According to the results, the SP/DS ratio of 1:1 with gelatin and 100 ppm TNLC can be used in developing SP/DS blends as a highly acceptable functional food., (© 2020 Wiley Periodicals, Inc.)

Recent studies of global subduction zones increasingly cite viscoelastic deformation as an important contributor to earthquake cycle mechanics and interpretation. Viscoelastic deformation in the asthenosphere of the overriding and down going plates effects the development of geologic structures, interpretation of interseismic deformation (locking models), and physics-based modeling of post-seismic deformation processes. In this presentation, we explore the existence and importance of viscoelastic deformation in a separate structure of the subduction zone: the accretionary prism. We present recent work on ongoing post-seismic deformation associated with the 2013 Mw7.7 Baluchistan earthquake that occurred within the accretionary prism of the Makran subduction zone of southern Iran/Pakistan. We constrained the Baluchistan earthquake post-seismic transient with Sentinel-1 interferometric synthetic aperture radar (InSAR) time series analysis, and we found that the transient cannot be explained by stress-driven afterslip. Instead, we explored a suite of semi-analytical models of viscoelastic relaxation and found that the transient is well-explained by deformation within a viscoelastic wedge embedded inside the accretionary prism. This viscoelastic wedge extends from the base of the seismogenic zone (6-8 km) down to the Arabian slab interface at 20-25 km depth. We resolved viscosities of 1017-1018 Pa s, and these viscosities are likely transient, as evidenced by the requirement of power-law viscoelastic deformation with a power-law exponent of n = 3.5. The power-law viscoelastic relaxation implies that creep processes, which are common at lower crustal and mantle temperatures, are active at comparatively lower temperatures within the Makran accretionary prism. We stipulate that this may be due to the presence of fluids introduced by sedimentary underplating and hydrocarbon production. Lastly, we highlight the influences of a partially viscoelastic accretionary prism on estimates of megathrust locking. Specifically, we show that the presence of an un-modeled viscoelastic accretionary prism leads to over-estimation of megathrust hazard. These results highlight the importance of measuring active deformation in accretionary prisms through seafloor geodetic observations in other subduction zones where the accretionary prism is submarine. [ABSTRACT FROM AUTHOR]

The effects of ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) methods on molecular and physicochemical characteristics of the resultant gelatin were examined. Before extraction procedure, we investigated the optimum pH for swelling of Common carp by-products, which is an important pretreatment for gelatin production. The highest swelling yield was achieved at pH 13 among pH 1-14 with unit intervals. Results indicated that the UAE gelatin has a higher gel strength, viscosity, melting point, and gelling point. The power and time of sonication showed a reverse relation with these characteristics. In addition, as the time of microwave heating was raised, the gel strength, viscosity, melting point, and gelling point were decreased. The FT-IR spectra showed similar peaks but the Amide B in UAE gelatin slightly vanished. The electrophoretic pattern also revealed the higher gel strength and viscosity of UAE gelatin due to the higher intensity of α and β chains compared to MAE gelatin. It can be concluded from all of the results of this study that the produced gelatin using these procedures can be a good source of gelatin in food and drug industries., (© 2019 Wiley Periodicals, Inc.)

The effect of different concentrations of gum tragacanth on the textural characteristics of low-fat Iranian White cheese was studied during ripening. A batch of full-fat and 5 batches of low-fat Iranian White cheeses with different gum tragacanth concentrations (without gum or with 0.25, 0.5, 0.75, or 1 g of gum/kg of milk) were produced to study the effects of fat content reduction and gum concentration on the textural and functional properties of the product during ripening. Cheese samples were analyzed with respect to chemical, color, and sensory characteristics, rheological parameters (uniaxial compression and small-amplitude oscillatory shear), and microstructure. Reducing the fat content had an adverse effect on cheese yield, sensory characteristics, and the texture of Iranian White cheese, and it increased the instrumental hardness parameters (i.e., fracture stress, elastic modulus, storage modulus, and complex modulus). However, increasing the gum tragacanth concentration reduced the values of instrumental hardness parameters and increased the whiteness of cheese. Although when the gum concentration was increased, the low-fat cheese somewhat resembled its full-fat counterpart, the interaction of the gum concentration with ripening time caused visible undesirable effects on cheese characteristics by the sixth week of ripening. Cheeses with a high gum tragacanth concentration became very soft and their solid texture declined somewhat.

The effect of milk coagulation temperature on the composition, microstructure monitored using scanning electron micrographs, opacity measured by a Hunter lab system, and rheological behavior measured by uniaxial compression and small amplitude oscillatory shear were studied. Three treatments of Iranian White cheese were made by applying coagulation temperatures of 34, 37, and 41.5 degrees C during the cheese-making procedure. A higher coagulation temperature resulted in increased fat and protein contents, and decreased the moisture content and ratio of moisture to protein. The highest temperature (41.5 degrees C) had a significant effect on the opacity of Iranian White cheese. Milk coagulation at this temperature decreased the whiteness index (Hunter L value) and increased the yellowness index (Hunter b value) of the aged product compared with cheeses coagulated at lower temperatures. Microstructure of the cheese coagulated at 41.5 degrees C was more compact and undisturbed, reflecting the higher values of stress at fracture and storage modulus measured for this treatment.

A batch of full-fat (23% target fat) and 3 batches of low-fat (6% target fat) Iranian white cheese with different rennet concentrations (1-, 2-, and 3-fold the normal usage) were produced to study the effect of fat content reduction and promoted proteolysis on the textural and functional properties of the product. Cheese samples were analyzed with respect to their rheological parameters (uniaxial compression and small amplitude oscillatory shear), meltability, microstructure, and sensory characteristics. Reduction of fat content from 23 to 6% had adverse effects on the texture, functionality, cheese-making yield, and sensory characteristics of Iranian white cheese. Fat reduction increased the instrumental hardness parameters (storage modulus, stress at fracture, and Young's modulus of elasticity), decreased the cheese meltability and yield, and made the microstructure more compact. Doubling the rennet concentration reduced values of instrumental hardness parameters, increased the meltability, and improved the sensory impression of texture. Although increasing the rennet concentration to 2-fold the normal usage resembled somewhat the low-fat cheese to its full-fat counterpart, it appeared to cause more reduction in yield. Increasing the rennet concentration 3-fold the normal usage produced a product slightly more elastic than the low-fat cheese with normal concentration of rennet. Increasing the rennet concentration to 2-fold the normal usage was useful for improving the textural, functional, and sensory properties of low-fat Iranian white cheese.