• Preventive Nutrition and Food Science
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• v.21 no.1
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• pp.73-77
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• 2016

Flow and dynamic rheological properties of thickened waters prepared with commercial food thickeners were investigated at different pH levels (3, 4, 5, 6, and 7). The commercial xanthan gum (XG)-based thickener (thickener A) and starch-based thickener (thickener B), which have been commonly used in a domestic hospital and nursing home for patients with swallowing difficulty (dysphagia) in Korea, were selected in this study. Thickened samples with both thickeners at different pH levels showed high shear-thinning flow behaviors (n=0.08~0.22). Thickened samples at pH 3 showed higher n values and lower consistency index (K) values when compared to those at other pH levels. The K values of thickener A increased with an increase in pH level, while the n values decreased, showing that the flow properties greatly depended on pH. There were no noticeable changes in the K values of thickener B between pH 4 and 7. At pH 3, the thickened water with thickener A showed a higher storage modulus (G') value, while that with thickener B showed a lower G'. These rheological parameters exhibited differences in rheological behaviors between XG-based and starch-based thickeners, indicating that the rheological properties of thickened waters appear to be greatly influenced by the acidic condition and the type of food thickener. Appropriately selecting a commercial food thickener seems to be greatly important for the preparation of thickened acidic fluids with desirable rheological properties for safe swallowing.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.306-312
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• 1998

This paper describes syntheses of thickener for di-urea grease using constant velocity joint. The thickeners of di-urea grease were synthesized by reaction of diisocyanate with various alkylamines, hexylamine, octylamine, stearylamine and cyclohexylamine at high temperatxire. The synthesized thickener were analyzed by FT-IR spectroscopy and two kinds of Mass spectroscopy (EI & FAB). Dropping point and Consistency of synthesized di-urea grease were determined.

• Preventive Nutrition and Food Science
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• v.19 no.3
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• pp.242-245
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• 2014

The flow behaviors of three thickened fruit juices (orange, apple, and grape juice) prepared with a commercial instant xanthan gum (XG)-based thickener that is marketed in Korea were investigated at different thickener concentrations (1.0%, 1.5%, 2.0%, 2.5%, 3.0%, and 3.5%) and setting times (5 and 30 min) using a rheometer and a line-spread measurement method. The flow distance values measured by the line-spread test (LST) were compared with the apparent viscosity (${\eta}_{a,50}$) values measured with a sophisticated computer-controlled rheometer. The ${\eta}_{a,50}$ values of the juices increased as thickener concentration increased, whereas their flow distances decreased. The ${\eta}_{a,50}$ values at the 30-min setting time were much higher than those at the 5-min setting time, indicating that the setting time before serving or consuming thickened juices can affect viscosity values. Plots comparing ${\eta}_{a,50}$ values to LST flow distances revealed strong exponential relationships between the two measures ($R^2$=0.989 and $R^2$=0.987 for the 5- and 30-min setting times, respectively). These results indicate that the LST can be a suitable instrument for evaluating the viscosity of thickened fruit juices prepared with different XG-based thickener concentrations and setting times for the dysphagia diet.

• Preventive Nutrition and Food Science
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• v.20 no.2
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• pp.137-142
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• 2015

Rheological properties of thickened fluids used for consumption by people with dysphagia (swallowing difficulty) are very sensitive to several factors, such as thickener type, temperature, pH, sugar, protein, and NaCl. In this study, steady and dynamic rheological properties of thickened water samples mixed with five commercial xanthan gum-based food thickeners (A~E) were studied in the presence of NaCl at different concentrations (0.3%, 0.6%, 0.9%, and 1.2%). The magnitudes of apparent viscosity (${\eta}_{a,50}$), consistency index (K), yield stress (${\sigma}_{oc}$), and dynamic moduli (G' and G") showed significant differences in rheological behaviors between thickened samples with various NaCl concentrations. Dynamic moduli values of all thickened samples, except for samples with thickener C, were much higher than those of the control (0% NaCl). All rheological parameter values (K, G', and G") in a thickener A were much higher than those in other thickeners. These results suggest that rheological properties of thickened samples containing NaCl are strongly affected by xanthan gum-NaCl interaction and depended on the type of thickener.

• Clinical Nutrition Research
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• v.11 no.1
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• pp.1-8
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• 2022

Food thickeners are commonly used to prepare thickened liquids for the management of dysphagia. The National Dysphagia Diet (NDD) thickness levels of thickened liquids prepared with commercial food thickeners are known to vary depending on the thickener type, recommended amount of thickener, thickener brand, and preparation instructions. Particularly, detailed preparation instructions must be provided by the manufacturers to achieve the correct thickness levels. However, the rheological information on product labels provided by manufacturers is typically not accurate. Here, various pudding-thick liquids were prepared by mixing commercial xanthan gum (XG)-based thickeners based on the manufacturers' guidelines, and their rheological properties were characterized. Several thickened liquids prepared with four different XG-based thickeners (A-D) marketed in Korea did not meet the pudding-like criterion (> 1,750 mPa·s) based on the NDD guidelines. Significant differences in rheological parameter values (η_a,50, n, and G') were also identified among the various thickened liquids. Only one thickener (thickener A) manufactured in Korea showed optimal results, which satisfied the pudding-thick viscosity range for various food liquids and also showed lower stickiness and enhanced bolus formation ability for easy and safe swallowing when compared to other thickeners (B, C, and D).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.101-106
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• 2009

We study on the segregation reduction effect of Self-Leveling Color Mortar by using variable composition set of plasticizer and thickener, Naphthalene, melamine and polycarbonate-based dispersants were employed as plasticizers for examining on fluidity of mortar mixtures. For enhancement of mortar stability without loss of it's fluidity, two types of thickener were used such as polysaccharide(PS) and hydroxyethylcellulose(HEC). As a result, the most effective mortar was composed by feeding 0.519% of polycarbonate-based dispersant with 0.002587% of PS and 0.155844% of HEC on amount of basic mortar.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.173-184
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• 1976

A steel capillary viscometer was built for the study of rheological properties of greases. Bentone greases with thickener concentration of 2.0, 4.0, 6.0, 8.0, and 10.0 weight percent and lime-soap greases with soap concentrations of 2.4, 7.0, 9.3, 12.1 and 15.2 weight percent were studied. Capillaries with various radii R and lengths L were used to study the resident-time effect on the flow properties of lime soap greases. Detailed studies on bentone greases were conducted using a capillary with a fixed size. The results were analyzed by using Ree-Eyring flow equation. The factors appearing in the latter, ($X_1{\beta}_1/{\alpha}_1$ for Newtonian units, $X_2/{\alpha}_2$ and ${\beta}_2$ both for non-Newtonian units), were studied in order to investigate how they change with thickener concentrations and temperatures. Through this analysis, we have found that TEX>${\Delta}H_1^{\neq}$ and ${\Delta}H_2^{\neq}$, the activation enthalpies for flow of type-1 unit and of type-2 unit, respectively, are approximately equal to that of the base oil, the solvent. From this fact, it is concluded that these type units flow into the holes which were produced by the movement of solvent molecules. For bentone greases, the ${\beta}_2$ is about constant independent of concentration at a given temperature as found in the literature. The resident-time effect has not been clearly demonstrated in this research; this is due partly to the nature of the greases used in our research and partly to the small values of L/R of our capillaries, the resident time being proportional to the value L/R.

• Tribology and Lubricants
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• v.28 no.1
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• pp.33-37
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• 2012

Automotive wheel bearing grease helps to reduce stresses and prevent wear of wheel bearings. But it is easily contaminated by water and other contaminants. Previously, our research group reported the change of grease physical properties such as dropping point, work penetration and oxidation work stability, water washout characteristics, leakage tendency, oil separation, evaporation loss and rust protection by water contamination. In this paper, we analyzed the physical characteristics of grease such as lubricity, viscosity and total acid number to investigate the mechanism of thickener decomposition. In water contaminated grease, the total acid number and wear scar were increased, the viscosity was decreased due to the decomposition of lithium complex thickener.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.673-678
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• 1997

Associative acrylic thickeners were prepared by emulsion copolymerization using nonionic vinyl surfactant esters as an associative macromonomer and their rheological properties were investigated. The thickening efficiency was shown to depend on the chain length of therminal hydrophobe and degree of ethoxylation of VSE. increasing the content of VSE enhanced the efficiency of the resulting polymers as a thickener. It was attributed to the intermolecular association of terminal hydrophobes of associative thickener in aqueous solution. The chain transfer agent caused to reduce the molecular weight of associative thickener, resulted in decrease of thickening efficiency.

• Korean Journal of Food Science and Technology
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• v.49 no.3
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• pp.229-234
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• 2017

For elderly individuals with swallowing difficulties, texture-modified food containing thickeners is needed. The plant materials freeze-dried yam, lotus root, and artichoke were evaluated for their potential use as thickeners and compared to a commercial thickener (corresponding to 0.5, 1, or 2 bag viscosity, respectively). Yam powder showed a high peak viscosity, corresponding to that of rice starch. Although artichoke showed no pasting viscosity, it may be useful as a thickener when combined with xanthan gum. The certain amount of yam, lotus root, and artichoke powders added to commercial soup showed similar viscosities as the addition of 0.5 or 1 bag commercial thickener at $60^{\circ}C$. However, sufficient viscosity corresponding to that of 2 bags of commercial thickener was not achieved by using the plant material itself. Sensory tests by elderly subjects revealed that the soup with yam powder was preferred compared to soup made with other materials.