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: 180Citation - Scopus: 208Incorporating Phenolic Compounds Opens a New Perspective To Use Zein Films as Flexible Bioactive Packaging Materials(Elsevier Ltd., 2011) Arcan, İskender; Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyTo eliminate their classical brittleness and flexibility problems zein films were plasticized by incorporation of different phenolic acids (gallic acid (GA), p-hydroxy benzoic acid (HBA) or ferulic acids (FA)) or flavonoids (catechin (CAT), flavone (FLA) or quercetin (QU)). The use of GA, CAT, FA and HBA at 3mg/cm2 eliminated the brittleness of films and gave highly flexible films showing elongations between 135% and 189%, while FLA and QU caused no considerable effect on film elongation. The films containing FA and HBA showed extreme swelling and lost their structural integrity when hydrated in distilled water. In contrast, CAT and GA containing films maintained their integrity following hydration. Most of the GA (up to 93%) and a considerable portion of CAT (up to 60%) in the films existed in soluble form. Therefore, the films showed antioxidant and/or antimicrobial activity. The TEACs of soluble phenolic compounds in 3mg/cm2 CAT and GA containing films were 21.0 and 86.2μmoltrolox/cm2, respectively. The GA containing films showed antimicrobial activity on Listeria monocytogenes and Campylobacter jejuni, while CAT showed no antimicrobial activity on these bacteria at the studied concentration. This work opens a new perspective for using zein in flexible bioactive packaging.Article Citation - WoS: 40Citation - Scopus: 45Phenolic Characterization and Geographical Classification of Commercial Extra Virgin Olive Oils Produced in Turkey(John Wiley and Sons Inc., 2012) Alkan, Derya; Tokatlı, Figen; Özen, Fatma Banu; Tokatlı, Figen; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aim of this research was to characterize the extra virgin olive oil samples from different locations in the Aegean coastal area of Turkey in terms of their phenolic compositions for two consecutive years to show the classification of oil samples with respect to harvest year and geography. Forty seven commercial olive oil samples were analyzed with HPLC-DAD, and 17 phenolic compounds were quantified. Hydroxytyrosol, tyrosol, vanillic acid, p-coumaric acid, ferulic acid, cinnamic acid, luteolin and apigenin were the characteristic phenols observed in all oil samples for two harvest years. Syringic acid, vanillin and m-coumaric acid were the phenolic compounds appeared in the olive oil depending on the harvest year. Partial least square-discriminant analysis (PLS-DA) of data revealed that oils from the north Aegean and south Aegean areas had different phenolic profiles. The phenolic compounds, which played significant roles in the discrimination of the olive oils, were tyrosol, oleuropein aglycon, cinnamic acid, apigenin and hydroxytyrosol to tyrosol ratio. The Aegean coastal region is the largest olive oil producer and exporter of Turkey. This study shows that the olive oils from different parts of the region have their own defining characteristics that can be used in the authentication studies and geographical labeling of Turkish olive oils. © AOCS 2011.Article Citation - WoS: 7Citation - Scopus: 6Water-Soluble Antioxidant Potential of Melon Lines Grown in Turkey(Taylor and Francis Ltd., 2012) Şelale, Hatice; Şığva, Hasan Özgür; Şelale, Hatice; Doğanlar, Sami; Frary, Anne; Frary, Anne; Doğanlar, Sami; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe antioxidant potential of 42 melon (Cucumis melo) lines including six cultivars grown in Turkey was assessed by measuring total water-soluble antioxidant capacity, phenolic and vitamin C contents. The lines showed significant variability for all three antioxidant parameters with breeding lines having higher antioxidant capacity and phenolic content than some popular cultivars. Different types of melons also showed significantly different antioxidant potentials. Thus, galia and ananas types showed a higher mean antioxidant capacity and phenolic content than the other tested types (yuva, kislik, canary, and charentais). Correlation analysis between antioxidant parameters showed a significant correlation between water-soluble antioxidant capacity and phenolic content. © 2012 Copyright Taylor and Francis Group, LLC.Article Citation - WoS: 19Citation - Scopus: 23Inhibition of Catechol-O (comt) by Some Plant-Derived Alkaloids and Phenolics(Elsevier Ltd., 2010) Yalçın, Dilek; Bayraktar, Oğuz; Bayraktar, Oğuz; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, as an alternative to the medicines, natural compounds extracted from plant species (Peganum harmala, Cistus parviflorus and Vitex agnus-cactus) were investigated in order to inhibit the catechol-O-metyhltranferase (COMT) activity. In fluorometric enzyme assay, S-adenosylmethionine (SAM) and aesculetin (ES) were used as methyl donor and acceptor substrates, respectively. Their Km values were determined as 3.5 ± 0.3 μM and 6.4 ± 0.4 μM in absence of inhibitor. Inhibition performances of the plant-derived polyphenolics and alkaloids were determined. Inhibitory effect of alkaloids extracted from P. harmala seeds was found the highest among the plant extracts; however, it was lower than that of 3,5-DNC. In case of inhibition mechanism, mixed type inhibition was observed for alkaloid extract whereas uncompetitive inhibition was observed for 3,5-DNC. In case of polyphenolic extracts obtained from C. parviflorus and V. agnus-cactus leaves, mechanism were also explained as mixed type inhibition and their αKi values were calculated as 1.99 ± 0.35 μg/ml and 9.48 ± 0.58 μg/ml, respectively. © 2009 Elsevier B.V. All rights reserved.Article Citation - WoS: 98Citation - Scopus: 108Capacity and Mechanism of Phenol Adsorption on Lignite(Elsevier Ltd., 2006) Polat, Hürriyet; Polat, Mehmet; Molva, Murat; Polat, Hürriyet; Polat, Mehmet; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyA raw lignitic coal from Soma, Turkey was investigated to determine its potential as an adsorbent for phenol removal from wastewaters. Kinetic batch tests demonstrated that phenol could be completely removed from solution given sufficient solids loading and reaction time. The adsorption capacity of 10 mg/g obtained with the lignite is low compared to those achievable with activated carbons (around 300 mg/g). However, when normalized for the surface area, the adsorption capacity was much larger for the lignite (1.3 mg/m2) than that generally observed with activated carbons (0.05-0.3 mg/m2). Hydrogen-bonding of the phenolic -OH with the oxygen sites on the lignite surface is the most likely mechanism for adsorption. Though water molecules also have affinity for the same oxygen sites, lateral benzene ring interactions make phenol adsorption energetically more favorable. Since phenol molecules adsorbed in this fashion would project their benzene rings into solution, formation of a second layer through the action of the dispersive π-π interactions between the benzene rings is very likely. Residual water quality with respect to major elements and heavy metals was within acceptable limits defined by the ASTM standards. Dissolution of organic matter from the lignite was also observed to be negligible.Article Citation - WoS: 22Citation - Scopus: 21A Novel Silk Fibroin-Supported Iron Catalyst for Hydroxylation of Phenol(John Wiley and Sons Inc., 2006) Pekşen, Bahar Başak; Üzelakçil, Caner; Bayraktar, Oğuz; Malay, Özge; Bayraktar, Oğuz; Üzelakçil, Caner; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aim of this study was to explore the potential use of silk fibroin (SF) as a catalyst support material for phenol hydroxylation reactions. Iron-substituted silk fibroin fibers were prepared using formic acid at room temperature and characterized using inductively coupled plasma atomic-emission spectrometry, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and optical microscopy. Measurement of an FTIR spectrum showed that the secondary structure was β-structure before and after iron substitution. To evaluate the catalytic properties of prepared catalyst, phenol hydroxylation reaction was carried out using aqueous hydrogen peroxide as an oxidant. An excellent transformation of phenol into dihydroxybenzenes (catechol and hydroquinone) was achieved. Phenol conversions of 3.3%, 61.2%, and 80.3% were obtained at room temperature, 40°C and 60°C respectively. It was found that no further phenol conversion proceeded because catalysts became separated from the reaction system during the reaction. No significant leaching of the iron was detected. Catalyst could be reused several times without a significant change in activity. Parent silk fibroin fibers without iron were inactive.