SIFAT REOLOGI DAN STABILITAS FISIK MINUMAN EMULSI MINYAK SAWIT

Influence of lactose on the rheological properties of reconstituted casein micelles concentrates

Rheological behaviour of emulsions of avocado and watermelon oils during storage

The influence of five different emulsifying salts on casein peptization (dissociation) and apparent viscosity of processed Gouda cheese was studied. Casein peptization was evaluated as peptization coefficient in the final product, while apparent viscosity was determined as flow behavior and consistency indices in the product during processing before cooling. Increasing moisture content and pH of processed cheese samples generally increases peptization coefficient, however the type of emulsifying salt showed to play an important role also. On the contrary, independently of the type of emulsifying salt, predictive regression models were suggested in order to express flow behavior index and consistency index versus chemical composition and pH. Increasing moisture content or reducing pH increases the flow behavior index. Consistency index, and thus the apparent viscosity, of processed cheese samples was increased when the moisture content was reduced, and when pH and the soluble casein content were increased.

The rheological and sensory properties kind (apricot, grape and mulberry molasses) blends were studied pestil (rollband) syrup of apricot, mulberry and grape at 25, 40, 50 and 70°C, rheological properties kind of pestil syrup (untreatment and treatment with sulphurapricot molasses) blends were studied using sugar concentrations of 0%, 5% and 10%. The empirical power law model fitted the apparent viscosityrotational speed data. All blends exhibited pseudoplasticbehavior. The syrup content and temperature influenced the flow behavior and consistency index values. Temperature sensitivity of the consistency index was assessed by applying an Arrhenius-type equation. Ea values ranged from 326,65 to 175,86 J mol s-1 as syrup content varied from apricot, grape to mulberry, respectively. Arrhenius constant, k, however, correlated with mouthcoating.

In this study, some physicochemical (solubility index, apparent density and dry matter content) and rheological properties of the hot salep, an indigenous Turkish beverage, were determined. The samples were prepared by adding water or milk to the commerical instant salep powder. The apparent viscosity of samples was measured in the temperature range of 10–50 °C, with the rotational speed of 20–200 rpm. The empirical power law model was used for the determination of the flow behavior and consistency indices of the samples. Dry matter content and apparent density of salp-milk beverage were significantly (p < 0.05) higher than those of salep-water counterpart. Apparent viscosity, consistency and flow behavior indices were also higher in the salep-milk samples. Salep-water sample was more pseudoplastic with lower flow behavior index. Since there is a close relationship between the rehological properties of beverages and consumer preference, the results might be useful in the formulation of instant hot salep beverages.

در این پژوهش تاثیر شرایط استخراج شامل زمان، نسبت حلال به آرد جو و pH بر ویژگی‌های فیزیکوشیمایی، رفتار جریان، پایدارکنندگی کف و امولسیون و رنگ بتاگلوکان استخراج شده از دانه جو بدون پوشینه رقم لوت توسط طرح مرکب مرکزی و به روش سطح پاسخ تعیین گردید. نتایج تجزیه و تحلیل آماری و ضرایب مدل‌ها نشان داد که مدت زمان استخراج، نسبت حلال به آرد جو و pH اثر معنی‌داری بر بازدهی و خلوص بتاگلوکان، پایداری کف و امولسیون، ضریب قوام (k)، شاخص رفتار جریان (n) و مولفه های رنگیL*، a* و b* داشت. افزایش زمان استخراج و نسبت حلال به آرد جو اثر مطلوبی بر بازدهی و خلوص بتاگلوکان استخراج شده گذاشت که این امر خود موجب بهبود خاصیت قوام‌دهندگی و ویژگی‌های رفتار جریان آن شد. از طرفی با افزایش قدرت قوام‌دهندگی بتاگلوکان، توانایی پایدارکنندگی سیستم‌های کف و امولسیون نیز افزایش یافت. افزایش pH موجب کاهش بازدهی استخراج و افزایش خلوص بتاگلوکان گردید. بهترین شرایط استخراج زمانی حاصل شد که زمان استخراج 90 دقیقه، نسبت حلال به آرد جو 10 به 1 و pH، 33/7 بود. در این نقطه بهینه، بازدهی استخراج، 12/4 درصد؛ خلوص، 11/69 درصد؛ پایداری کف، 95/86 درصد؛ پایداری امولسیون، 77/88 درصد؛ ضریب قوام، Pa.sn 51/1؛ شاخص رفتار جریان، 62/0؛ L*، 42/73 ؛ a*، 81/0 و b*، 72/8 بود.

Hydraulic analysis of the wellbore has become increasingly important for designing cementing operations and selecting equipment, materials and techniques to complement modern well-completion practices. Non-Newtonian fluid technology has advanced beyond the point where former empirical methods of analysis adequately define the hydraulic system and fluid properties. In view of these factors, this paper describes a series of rheological calculations which have been found practical, through field usage, for assistance in selecting a cementing program. A relatively simple laboratory method using standard viscometric equipment is suggested for determination of the rheological properties of slurries, and data are presented on some of the more common cementing compositions. A criterion for divergence from laminar-flow characteristics has been proposed. Usefulness of the calculations is indicated by examples of cementing operations where they have been used. Introduction With the changing aspects of well-completion practices during the past few years, it has been increasingly important to have a relatively simple method of analyzing the flow conditions existing in the well during cementing operations. This is particularly true in view of the improved economics toward which most of the changes have been directed. Rheological characteristics of slurries used for cementing should be a major consideration in the trend toward smaller casing sizes, either single or multiple strings. Receiving increased attention is the practice advocated in 1948 by Howard and Clark of attaining turbulent flow with the fluids circulated during a primary cementing operation. While there may still be a difference of opinion concerning this technique, most available information indicates that superior primary-cementing results are generally obtained when high displacement rates are employed. Fluid properties of the slurry to be used must be available, as well as calculation methods, to determine what flow rates should be attained and the probable consequences in terms of frictional pressure and horsepower utilization. It would certainly be inappropriate to attempt high displacement velocities if sufficient pressure might be developed to create lost circulation. Since cementing slurries are non-Newtonian fluids, it is not possible to define their rheological or fluid properties by the single factor of viscosity and then make calculations for the quantities just described. Because the shear stress-shear rate ratio is not constant, it becomes necessary to establish at least two parameters for adequate fluid-flow calculations. It is not the purpose of this paper to delve into the mathematical development of non-Newtonian technology, nor to discuss the arbitrary classification system under which a single fluid may resemble two or three different classes depending upon experimental conditions. Rather, the intention is to present a useful series of calculations based on a concept applicable to both Newtonian fluids and to the preponderance of non-Newtonian fluids encountered in the oil-producing industry. Development of this approach was begun some 32 years ago, and has most recently been brought to fruition by Metzner and his co-workers at the U. of Deleware. Some non-Newtonian fluids encountered in the petroleum industry, other than cementing slurries, have also had the benefit of this method of analysis. The two parameters required to define the fluid are usually denoted by the symbols and and, for the purposes of this discussion, are called "flow behavior index" and "consistency index", respectively. These two slurry properties permit calculation of the Reynold's number and the "critical" velocity, or the velocity at which departure from laminar flow begins. EXPERIMENTAL DETERMINATIONS The two principal instruments used for rheological studies are the pipeline (capillary-tube) viscometer and the rotational viscometer. When conveniently possible, a capillary-tube viscometer (where the pressure drop and flow rate of the material can be measured) is the better method for rigorous determination of the flow behavior index and consistency index for non-Newtonian fluids. With pressure-drop data at various flow rates, it is then possible to prepare a logarithmic plot of shear rate as the abscissa-shear stress as the ordinate. For fluids which do not exhibit time-dependency, these data will usually produce a straight line. The flow behavior index represents the slope of this line, while the consistency index becomes the intercept of this line at unity shear rate in accordance with the mathematical derivations associated with this concept of rheology. Due to the difficulties anticipated in maintaining a uniform, pumpable cement slurry for the time interval required to obtain measurements from the pipe viscometer, the and data reported herein were obtained using a direct-indicating rotational viscometer (Fig. 2). JPT P. 323^

Rheological and sensory properties of pekmez (grape molasses)/tahin (sesame paste) blends

In this study, pectin was extracted from the pistachio hull using two methods: conventional extraction and ultrasound-assisted extraction. Water and citric acid solution were tested separately as extraction solvents in both conventional and ultrasound methods. The highest yield (32.3 ± 1.44%) was obtained using a citric acid solution in the conventional extraction method. The pectin extracted with this method had 38.94 g acid per 100 g dry pectin extract. The galacturonic acid and ash contents were 65.81 ± 1.51 and 1.57 ± 0.03%, respectively. The pistachio hull pectin was under the low methoxy pectin group with a 19.29 ± 0.41% degree of esterification. The emulsifying property of the pectin extracted was investigated in an oil-in-water emulsion system at six different pectin concentrations (2, 4, 5, 6, 8, and 10% w/w) and at a fixed oil ratio (20% w/w). Emulsion performance was investigated in terms of emulsion stability, microstructural characteristics, droplet size, and rheological properties. The most stable emulsion was obtained at a 6% pectin concentration. The emulsifying activity index, emulsion stability index, droplet size, consistency index, and flow behavior index were 172.85 ± 0.59 m2/g, 158.28 ± 3.41 min, 6.08 ± 0.04 µm, 0.72 ± 0.001 Pa·s n , and 0.752 ± 0.005 at this concentration, respectively.

A study on the rheological behaviour of carob juice was carried as a function of solid concentration, in the range 25-45 °Brix, at different temperatures (20-60 °C), with a rotational viscometer. The viscosity decreased with an increase in temperature. Using Herschel-Buckley model, both flow behaviour index (n) and consistency index (K) were determined. The calculated values of flow behaviour index were less than 1 at all temperatures and concentrations. Therefore, the carob juice was well described by the Pseudoplastic behaviour. The Herschel-Buckley model represented well the rheological data, with high values for the determination of coefficient (R2). The effect of temperature on viscosity was evaluated by using an Arrhenius type equation. The activation energy (Ea), at a shear rate of 12.2 s-1, was found in the range of 1.77-10.25 kJ/mol.

Pekmez, also known as a concentrated grape juice, was spray dried in a laboratory‐type pilot drying unit to obtain pekmez powder (PP). The flow characteristics of PP, wheat starch (WS) and some dairy by‐products (whey powder, skim milk powder, calcium caseinate and sodium caseinate) systems as binary and ternary mixtures were studied. The empirical power law model fitted the apparent viscosity–rotational speed data. PP–dairy by‐product and WS–dairy by‐product mixed solutions exhibited a shear‐thinning behavior at 21C with flow behavior index (n) values of 0.86 ≤ n ≤ 0.92 and 0.06 ≤ n ≤ 0.27, respectively. WS–dairy by‐product mixed solutions showed high shear‐thinning behavior with the highest consistency index (k = 25,425–180,599 mPa·sn). However, PP–WS and PP–WS–dairy by‐product mixed solutions at the same temperature exhibited the shear‐thickening behavior with flow behavior index (n) values of 1.05 ≤ n ≤ 1.18.PRACTICAL APPLICATIONSPekmez has become popular as a healthy food product; therefore, its rheologic properties were extensively studied by some researchers. However, pekmez powder (PP) is a new product and has not been produced yet in the food industry. Spray drying of foods has been spread recently in almost all food industry branches because it provides some advantages such as extending the shelf life, storage stability, decreasing the storage costs of the food products, etc. For this reason, production technology is first developed; PP is produced and studied in this study. There is no published data informing the rheologic, physical and sensory properties of pekmez or PP as binary and ternary mixtures with other components such as wheat starch (WS) and any dairy by‐product. The purpose of this study was mainly to characterize the rheologic behavior of the PP–WS–dairy by‐product mixed solutions and determine their physical and sensory properties.

In this study, the droplet size distribution, rheological properties, and stability of dairy cream-based emulsions homogenized with different sucrose fatty acid ester (SFAE, a non-ionic small-molecule emulsifier) concentrations (0.08%, 0.16%, and 0.24% w/w) at different homogenization pressures (10 MPa and 20 MPa) were examined. Homogenization at a high pressure resulted in a smaller droplet size and narrower droplet size distribution. The D[4,3] (volume-weighted mean) and D[3,2] (surface-weighted mean) values of the emulsions decreased with an increase in the SFAE concentration. The flow properties of the emulsions homogenized with SFAE showed shear-thinning (n=0.21–0.46) behavior. The apparent viscosity (ηa,10) and consistency index (K) of the homogenized emulsions were lower than those of the control sample that is non-homogenized and without SFAE, and decreased with an increase in SFAE concentration. The storage modulus (G') and loss modulus (G") of all emulsions homogenized with SFAE were also lower than those of the control sample. The stability of all emulsions with SFAE did not show any significant change for 30 d at 5°C. However, the emulsions stored at 40°C were unstable over the storage period. Therefore, the addition of SFAE enhanced the stability of dairy cream emulsions during storage at refrigeration temperature (5°C).

Polysaccharides may enhance/inhibit lipid digestibility of oil-in-water (O/W) emulsions because of their emulsifying and/or stabilizing ability and can also affect the formation, stability, and viscosity of emulsions. Tamarind seed gum (TSG) was used as the sole emulsifier/stabilizer to stabilize an O/W emulsion prepared using high-speed homogenization. We investigated the effects of various TSG concentrations (50-150 g kg-1 ) on the lipid digestibility, rheological properties, and stability of O/W emulsions during in vitro gastrointestinal digestion. A low concentration (50 g kg-1 ) and a high concentration (150 g kg-1 ) of TSG reduced lipid digestibility by about 33% and 45%, respectively, compared to the control sample (without TSG). However, the emulsion containing the intermediate TSG concentration at 100 g kg-1 was the most efficient in the inhibition of lipid digestion, reducing lipid digestibility by about 70% compared to that of the control sample. The stability of emulsion tended to enhance as the concentration of TSG increased. The size of oil droplets before passing through the intestinal phase and the viscosity of the intestinal digested system may be important factors for enhancing/inhibiting lipid digestibility of emulsions. The destabilization of the emulsion during digestion was not clearly detected by rheological analysis because rheological characteristics (e.g. flow behavior index) were mainly driven by TSG. The addition of TSG in O/W emulsions inhibited lipid digestibility. TSG at a concentration of 100 g kg-1 was the most efficient in the inhibition of lipid digestibility, suggesting that TSG is an attractive alternative ingredient for control of lipid digestibility of emulsion foods. © 2020 Society of Chemical Industry.

The effect of the flower and pine honey on the rheological behavior of kefir was investigated. Major aim was to produce a new functional fermented milk beverages with honey. Soluble solid was changed from 6.37 to 25.28; refractive index values were between 1.342 and 1.374; pH was changed from 4.04 to 4.65 and color values, L of samples were determined as 63.10–73.18. The rheological properties of the samples were determined using a controlled stress rheometer. It was observed that an empirical power-law model was suitable to describe the rheological behavior of kefir with honey with correlation coefficients (R 2) between 0.991 and 0.96. The apparent viscosity of the kefir with honey decreased with increasing shear rate. Flow behavior index (n) and consistency index (K) values for the kefir with honey ranged from 0.3711 to 0.4691, 130 to 204 mPa s, respectively. The model kefir with honey was found to exhibit non-Newtonian behavior.

The article examines the properties of polymer-based drilling fluids formulated with natural polymers such as starch, cellulose-derived biopolymers, and lignosulfonates. The research focuses on key parameters – pseudoplasticity and filtration characteristics – critical for cleaning horizontal and deviated wellbores. Effective penetration into productive formations is achieved by minimizing filtrate intrusion and reservoir contamination, assessed via penetration depth based on adsorption properties of the reagents. A synergistic effect is observed when high-molecular-weight polysaccharides – xanthan gum, modified starch, and lignosulfonate – are combined, forming a protective screen within the pore channels of the formation through adsorption. Optimized quadratic equations predict flow behavior index and consistency index values for starch concentrations up to 0.4% and xanthan gum up to 3%. Joint application of starch and xanthan gum reduces the fluid filtration index 1.6-fold, lowers the flow behavior index 1.02-fold, and increases the consistency index nearly 1.2-fold. The best filtration and transport properties are achieved with 1.5% starch + 0.2% xanthan gum and 2% starch + 0.25% xanthan gum. The developed predictive method for polymer composition penetration is validated through experiments on limestone cores from the Yugomashevskoye field, evaluating the effect of polymer formulations on filtration-capacity properties.This approach enables optimization of polymer reagent concentrations, ensuring efficient use of costly additives and reducing well construction costs. It also supports safe drilling conditions, effective drill cuttings suspension, and improved cuttings transport. A visual model of the proposed solution is provided. Keywords: biopolymer reagents; cellulose; lignosulfonate; adsorption; oil; productive formation; drilling fluid.