Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 14Citation - Scopus: 25Kinetic and Equilibrium Studies of Adsorption of Ss-Glucuronidase by Clinoptilolite-Rich Minerals(Elsevier Ltd., 2015) Demirbüker Kavak, Dilek; Ülkü, SemraThe adsorption of the bacterial β-glucuronidase (GUS) enzyme, which is thought to be responsible for the production of reactive metabolites related to some diseases and cancer development, by clinoptilolite-rich mineral was investigated. Batch experiments were performed to analyze of the effects of the clinoptilolite amount and particle size, initial GUS concentration, shaking rate, pH and temperature on the adsorption equilibrium and kinetics. Adsorption equilibrium data were interpreted in terms of Langmuir and Freundlich isotherms; and they were well represented by the Langmuir isotherm model. The percentage of GUS removal by the clinoptilolite-rich mineral was changed in the range of 9.4-54.4% depending on its initial concentration. The kinetic data were analyzed using external film diffusion, intraparticle diffusion, pseudo-first-order and pseudo-second-order models and both external film and intraparticle diffusion appeared to be effective in GUS adsorption. Thermodynamic studies indicated that GUS adsorption is exothermic, physical and spontaneous at the temperatures investigated (288-310 K)Article Citation - WoS: 8Citation - Scopus: 7Potential Application of Hot Rehydration Alone or in Combination With Hydrogen Peroxide To Control Pectin Methylesterase Activity and Microbial Load in Cold-Stored Intermediate-Moisture Sun-Dried Figs(John Wiley and Sons Inc., 2004) Demirbüker Kavak, Dilek; Şimşek, Şebnem; Yemenicioğlu, AhmetSun-dried figs contain a considerable amount of pectin methylesterase (PME) activity (22 μM COOH/ min/g). The enzyme causes softening and loss of desired gummy texture in cold-stored intermediate-moisture (IM) sun-dried figs brought to a 28% to 29% moisture range. Partial reduction of PME activity (28%) delayed undesirable textural changes in IM figs rehydrated at 80°C for 16 min. The heat treatment did not cause a considerable reduction in microbial load. However, the addition of 2.5% H2O2 to the rehydratlon medium at 80°C reduced the initial total mesophilic aerobic count of figs by at least 90% and turned the figs from a brown color to a desirable and stable yellow-light brown. The in situ fig catalase remains after rehydration at 80°C. Thus, by reducing the contact period of figs with H2O2 or by pureeing figs, it is possible to eliminate residual H2O2 and to obtain safe and SO2-free light-colored fig products.