Yazar "Karaman S." seçeneğine göre listele

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    Effect of ultrasound treatment on steady and dynamic shear properties of glucomannan based salep dispersions: Optimization of amplitude level, sonication time and temperature using response surface methodology
    (2012) Karaman S.; Yilmaz M.T.; Ertugay M.F.; Baslar M.; Kayacier A.
    The present study investigated effect of different amplitude levels (40, 70 and 100%), sonication temperatures (40, 50 and 60 °C) and exposure times (3, 7 and 11 min) on steady shear properties; apparent viscosity (?), shear stress (?), consistency coefficient (K), flow behavior index (n) and dynamic shear properties; storage modulus (G?), loss modulus (G?), complex viscosity (?), complex modulus (G) and loss tangent (tan ?) values of glucomannan based salep solution (SS) and salep drink (SD) samples. In addition, the steady and dynamic shear properties were optimized using ridge analysis in terms of amplitude level, sonication temperature and exposure times levels. Increasing amplitude level and sonication time decreased considerably the ?, ?, K, G?, G? and ? values of salep dispersions (SS and SD samples). However, sonication temperature did not have a remarkable effect on these properties. © 2011 Elsevier B.V. All rights reserved.
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    Steady, dynamic and creep rheological analysis as a novel approach to detect honey adulteration by fructose and saccharose syrups: Correlations with HPLC-RID results
    (Elsevier Ltd, 2014) Yilmaz M.T.; Tatlisu N.B.; Toker O.S.; Karaman S.; Dertli E.; Sagdic O.; Arici M.
    In this study, natural honey was adulterated with the addition of adulterants, namely saccharose and fructose syrups at a ratio of 0%, 10%, 20%, 30%, 40% and 50% by weight. Steady, dynamic and creep tests were conducted, revealing that the changes in the flow, viscoelastic and creep behavior of natural honey were clear and remarkable. Syrup addition decreased viscosity (?), storage (G') and loss modulus (G?) values of the control honey samples. Deformation represented by the compliance (J(t)) values was more prominent in the adulterated honey samples. In addition, HPLC-RID analysis was conducted to determine major sugar composition of the adulterated samples. Pearson's correlation test indicated that there were significant (P<0.05; 0.01) correlations between sugar composition and rheology parameters, ? (viscosity), K?, K* (intercepts for G? and complex modulus (G*), respectively) and ?0 (viscosity of Maxwell dashpot), suggesting that K', K?, K* and ?0 could be prominent indicators for presence of saccharose or fructose syrups added in natural honey within the studied concentration levels. These results suggested that use of steady, dynamic and creep analysis would be a novel and potential approach to detect honey adulteration by fructose and saccharose syrups. © 2014.
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    Thermal loop test to determine structural changes and thermal stability of creamed honey: Rheological characterization
    (Elsevier Ltd, 2015) Karasu S.; Toker O.S.; Yilmaz M.T.; Karaman S.; Dertli E.
    This study was the first attempt to understand if thermal stability of any food product during storage could be determined. In this respect, a novel method, namely, the thermal loop test was used to determine structural changes and thermal stability of creamed honey in this study. The novelty of this method was that thermal stability of a product is tested within a number of thermal cycles over a determined range of temperature. Creamed honey was characterized in terms of physicochemical, thermomechanical and rheological properties. It showed non-Newtonian thixotropic behavior at all temperature levels (10, 25 and 40 °C). Time-dependent flow behavior was successfully defined by Weltman and second order structural models. Hysteresis loop area depended on temperature and decreased with increase in temperature. Creamed honey had liquid-like structure, showing that it had more pronounced viscous nature than elastic nature (G? > G?). Temperature sweep tests were conducted to determine temperature dependency of ?50, G? and G? values using Arrhenius equation. These test results confirmed the thermal stability test results, revealing that thermal loop test can be an accurate method to determine thermal stability of similar food products, as a new information. Relative structural index value (?) increased with number of thermal loop, suggesting that creamed honey had low thermal stability and showed a great structural change by the thermal stress applied between 5 °C and 50 °C. These results suggest that crystallized honey be abstained from large temperature fluctuations to avoid from irreversible changes in rheological characters; thus, to maintain spreadability. © 2014 Elsevier Ltd.