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: 1Citation - Scopus: 1Correlation of Low Field Nuclear Magnetic Resonance Relaxation With Composition and Glass Transition of Hard Candies(Frontiers Media S.A., 2024) Ozel, Baris; Berk, Berkay; Uguz, Sirvan Sultan; Grunin, Leonid; Oztop, Mecit HalilHard candies produced from sucrose and doctoring agents such as glucose syrup (GS) and high fructose corn syrup (FS) have been investigated in terms of their final composition, glass transition temperature (Tg), degree of crystallinity, total soluble solids (TSS) content and water activity (aw). Time domain (TD) 1H NMR longitudinal relaxation time (T1) and second moment (M2) measurements have been used to understand the glassy state and crystallization characteristics for different hard candy formulations. The investigated candies include sucrose as the main sugar component. Different levels of doctoring agents have been mixed with sucrose to obtain products with different characteristics. It has been shown that addition of any doctoring agent to sucrose formulations decreases the Tg of the system significantly (p <= 0.05). Furthermore, GS or FS addition also induce significant changes in TSS and aw. T1 and M2 results are almost parallel to each other, both reaching the highest values for the highest sucrose concentration (p <= 0.05). The results demonstrate that the glass transition and crystallization characteristics of hard candy formulations can be monitored and analyzed by TD NMR relaxometry, alternative to other frequently used conventional methods including differential scanning calorimetry (DSC) and X-ray diffraction.Article Citation - WoS: 3Citation - Scopus: 3Shelf-Life Extension of Traditional Licorice Root “sherbet” With a Novel Pulsed Electric Field Processing(Frontiers Media S.A., 2023) Akdemir Evrendilek, Gulsun; Demir, Irem; Uzuner, SibelPulsed electric field (PEF) processing of licorice root "sherbet" (LRS) by various electric field strengths (7.00, 15.50, and 24.10 kV/cm), treatment times (108, 432, and 756 mu sec), and processing temperatures (6, 18, and 30 degrees C) according to the Box-Behnken design were performed. The samples were analyzed for pH, titratable acidity, conductivity, turbidity, total reducing sugar, color (L*, a*, and b*), hue, chroma, total color difference, color intensity, color tone (yellow, red, and blue color tones), total antioxidant capacity, total phenolic substance content, and sensory properties. Results revealed that PEF processing did not adversely affect most of the physical, chemical, and sensory properties of LRS, with a maximum of 2.48, 4.04, 1.78, and 1.20 log reductions on the initial total mesophilic aerobic bacteria, total mold and yeast, Bacillus circulans, and Candida tropicalis. The response variable modeled for the PEF was found to be conductivity, with the optimum processing conditions of 6.90 kV/cm, 756.00 mu s, and 7.48 degrees C. After that, the samples were stored at 4 degrees C and 22 degrees C for shelf-life studies. Control samples at 4 degrees C and 22 degrees C were spoiled on the fifth and second days, whereas PEF-treated samples stored at 4 degrees C began to deteriorate after the 40th day and the samples stored at 22 degrees C after the 30th day, respectively. It was revealed that PEF is a suitable process to extend the shelf-life of licorice "sherbet" with preservation of physicochemical and sensory properties.Article Production of Microalgae-Derived Exo-Polygalacturonase for Fruit Juice Clarification(Frontiers Media S.A., 2022) Uzuner, Sibel; Evrendilek, Gulsun Akdemir; Kurhan, SebnemDue to the growing demand for commercial enzymes derived from renewable and sustainable resources with higher efficacy, algal biomass has gained more attention. Thus, the production of exo-polygalacturonase (PGase) from Bacillus subtilis under submerged fermentation (SmF) using algal feedstocks as a carbon source in fermentation medium and its potential use for the clarification of apple and carrot juices with the optimization of the enzyme loading, pH, and time using Box-Behnken response surface methodology (RSM) were prompted. The maximum PGase activity of 510.61 +/- 7.86 U/L was achieved at pH 5.0 after 48 h at 40 degrees C using 0.5% (w/v) pectin, 0.1% (w/v) yeast extract, 0.02% (w/v) MgSO47H2O, 0.02% (w/v) K2HPO4, 0.3% (w/v) glucose, and 0.583% (w/v) microalgae hydrolysate as a fermentation medium. PGase production without glucose was favored by SmF with a shake flask working volume of 100 ml (248.90 +/- 4.58 U/L) as compared to a bioreactor with a working volume of 1 L (192.99 +/- 0.84) for 48 h. Both carrot and apple juices were treated with the crude PGase (248.9 U/L) at different concentrations (0.1-0.5%), temperature (30-50 degrees C), and time (30-120 min), and the maximal clarification conditions were obtained as 0.3% (w/v) enzyme concentration at 50 degrees C for 30 min exposure time. This study revealed that microalgae-derived PGase in crude form could be effectively used for clarification of the juices.Article Citation - WoS: 3Citation - Scopus: 3A Perturbative Approach To the Tunneling Phenomena(Frontiers Media S.A., 2019) Erman, Fatih; Turgut, Osman TeomanThe double-well potential is a good example, where we can compute the splitting in the bound state energy of the system due to the tunneling effect with various methods, namely path-integral, WKB, and instanton calculations. All these methods are non-perturbative and there is a common belief that it is dif fi cult to fi nd the splitting in the energy due to the barrier penetration from a perturbative analysis. However, we will illustrate by explicit examples including singular potentials (e.g., Dirac delta potentials supported by points and curves and their relativistic extensions) it is possible to fi nd the splitting in the bound state energies by developing some kind of perturbation method.Article Citation - WoS: 5Citation - Scopus: 5The Propagators for Δ and Δ′ Potentials With Time-Dependent Strengths(Frontiers Media S.A., 2020) Erman, Fatih; Gadella, Manuel; Uncu, HaydarWe study the time-dependent Schrodinger equation with finite number of Dirac delta and delta ' potentials with time dependent strengths in one dimension. We obtain the formal solution for generic time dependent strengths and then we study the particular cases for single delta potential and limiting cases for finitely many delta potentials. Finally, we investigate the solution of time dependent Schrodinger equation for delta ' potential with particular forms of the strengths.