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Öğe Antibiotic resistance and virulence genes in Enterococcus species isolated from raw and processed seafood(Springer India, 2022) Cardak, Mine; Ozmen Togay, Sine; Ay, Mustafa; Karaalioglu, Onur; Erol, Ozlem; Bagci, UfukThis study evaluated the antibiotic resistance characteristics and virulence genes of enterococci isolated from raw and processed seafood sold in the Marmara Region, Turkey. In this context, the enterococcal load was determined as between 1.0 and 2.5 log CFU/g in 39 of a total of 397 samples. It was determined that 117 strains isolated from the samples belonged to Enterococcus gallinarum, E. casseliflavus, E. durans, E. faecium, and E. faecalis species. Erythromycin, tetracycline, streptomycin, and gentamicin resistance was observed, whereas the tetM, ermB, aac(6')-aph(2'')-la genes were found in a majority of the isolates. It was also determined that the isolates carried the agg2 and gelE virulence genes. When all these results are evaluated, the presence of these isolates in aquatic products may pose a risk in terms of food safety and public health.Öğe Clarification of Apple Juice Using Polymeric Ultrafiltration Membranes: a Comparative Evaluation of Membrane Fouling and Juice Quality(Springer, 2017) Gulec, Haci Ali; Bagci, Pelin Onsekizoglu; Bagci, UfukThe aim of this study was to evaluate the performance of three different commercial polymeric ultrafiltration (UF) membranes during clarification of raw apple juice, comparatively. The influence of membrane pore size, roughness, and hydrophobicity on flux profile and fouling was investigated. The initial flux was simultaneously decreased at the beginning of the process, and quite steady flux was obtained in the membranes with rougher surface and more hydrophobic nature. As the pore size and hydrophobicity increased, the reversible fouling became the major resistance, while cake formation was more prominent for the membranes with narrower pore size. The overall quality results revealed that the main quality characteristics of the raw juice can be better retained by using the membranes that have higher resistance to fouling.Öğe Coupling reverse osmosis and osmotic distillation for clarified pomegranate juice concentration: Use of plasma modified reverse osmosis membranes for improved performance(Elsevier Sci Ltd, 2019) Bagci, Pelin Onsekizoglu; Akbas, Meryem; Gulec, Haci Ali; Bagci, UfukIn this study, a low pressure nitrogen plasma (LPNP) activation was implemented to modify the surface characteristics of a commercial thin film composite (TFC) polyamide reverse osmosis (RO) membrane. The free energy of interaction (Delta G(iwi)) results showed that the hydrophobic nature of untreated TFC RO membrane became considerably hydrophilic with the effect of LPNP treatment. Among various plasma powers and exposure times tested, a general decreasing trend was observed for the water contact angle with increasing plasma duration, reaching a minimum of 13.2 +/- 0.8 degrees for 90 W at 15 min. A remarkable increase in water flux of the LPNP modified RO membrane was observed throughout the RO process, which promoted higher soluble solids content (SSC) values in the concentrated juice at the same period of time with the plain one. The higher SSC values achieved by the modified RO membrane enabled 30% time-saving during further osmotic distillation process.Öğe Modification of chia (Salvia hispanica L.) seed mucilage (a heteropolysaccharide) by atmospheric pressure cold plasma jet treatment(Elsevier, 2023) Mutlu, Sebnem; Palabiyik, Ibrahim; Kopuk, Berkay; Gunes, Recep; Boluk, Esra; Bagci, Ufuk; Ozmen, DuyguChia seeds (CS) were subjected to atmospheric pressure cold plasma jet (APCPJ) for different times (30, 60, and 120 s) by using argon gas, and then chia mucilage (CM) was extracted from the seeds to investigate the technological properties of mucilage (a heteropolysaccharide). The gel samples prepared from dried CM obtained from CS treated with 30 s and 120 s APCPJ showed noticeably higher consistency index of 11.43 and 13.63 Pa.sn, while the control and 60 s APCPJ showed a lower consistency index of 1.07 and 0.35, respectively. HerschelBulkley was better at defining the flow behavior of CM gels, and the treatment increased the shear-thinning and consistency properties. Moreover, CM gels of APCPJ-treated seeds (30 s and 120 s) showed higher elastic properties and better resistance against deformation. The treatment induced cross-linking between polysaccharide chains as confirmed by FTIR, and SEM micrographs demonstrated that APCPJ caused etching on the surface of seeds, thus a more compact structure was obtained in the hydrated mucilage samples depending on the APCPJ time. The highest treatment time (120 s) decreased the solubility, and the water (15%) and oil holding capacity (25%), while it did not significantly affect the emulsion ability and stability. In conclusion, it was found that the APCPJ improved the viscosity and elastic features of CM gels by cross-linking and strengthening the polymer network, which may provide opportunities to use this gum in new food applications.Öğe Performance enhancement of ultrafiltration in apple juice clarification via low-pressure oxygen plasma: A comparative evaluation versus pre-flocculation treatment(Elsevier Science Bv, 2018) Gulec, Haci Ali; Bagci, Pelin Onsekizoglu; Bagci, UfukThe aim of this study was to improve ultrafiltration (UF) performance during clarification of raw apple juice through surface modification of commercial polysulfone membranes (US100) by low-pressure oxygen plasma treatment (LP-OPlsT). A Plasma power of 90 W and exposure time of 10 min were determined as the most effective parameters enabling an increase in the Delta G(iwi) value of the plain membrane from (-) 25 +/- 2 mN m(-1) to (+) 30 +/- 1 mN m(-1). Improved hydrophilicity achieved by LP-OPlsT remarkably enhanced the performance of US100 throughout the clarification of raw apple juice without the need of an additional pre-flocculation step. While R-frev (86%) was the dominant resistance controlling the fouling during UF of raw apple juice through the plain membrane, the contribution of R-frev to R-t decreased to 56% after pre-flocculation step. LP-OPlsT further decreased this ratio, up to 46%, confirming the charge repulsion between the modified membrane and the foulant particles.Öğe Pomegranate juice concentration through the consecutive application of a plasma modified reverse osmosis membrane and a membrane contactor(Elsevier, 2020) Bagci, Pelin Onsekizoglu; Kahvecioglu, Hayriye; Gulec, Haci Ali; Bagci, UfukA low-pressure nitrogen plasma (LPNP) modified commercial thin-film composite membrane was used for pre-concentration of the clarified pomegranate juice (C-PJ) by reverse osmosis (RO). Pre-concentrates then submitted to osmotic distillation (OD) for further concentration. The productivity of the integrated membrane process was benchmarked considering both the performance and the final product quality. The modified RO membranes had great potential for shortening duration of consecutive concentration process, enabling up to 36% time saving during concentration of the C-PJ from 15.6 degrees Brix to >65 degrees Brix. Aroma losses observed in stand-alone OD are also prevented by shortening the duration of OD. Lower retention of malic acid, gallic acid, glucose, and fructose was observed due to the increased permeability following LPNP modification. However, these losses did not seem to affect the total acidity, total phenolic content, and total antioxidant activity of the concentrates obtained. The total color change was also in the range of barely noticeable values. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Öğe Probiotic characteristics of bacteriocin-producing Enterococcus faecium strains isolated from human milk and colostrum(Springer, 2019) Bagci, Ufuk; Togay, Sine Ozmen; Temiz, Ayhan; Ay, MustafaAs potential probiotic traits of human milk-isolated bacteria have increasingly been recognized, this study aimed to evaluate the probiotic properties of bacteriocin-producing Enterococcus faecium strains isolated from human milk and colostrum. Among 118 human milk- and colostrum-isolated lactic cocci, only 29 were identified as Enterococcus. Of these, only four Enterococcus faecium isolates exhibited bacteriocigenic activity against several pathogenic Gram-positive bacteria, including Listeria monocytogenes. These isolates exhibited high acid (up to pH 3.0) and bile tolerance (0.5% oxgall) in simulated gastrointestinal conditions, demonstrating their ability to survive through the upper gastrointestinal tract. All of the E. faecium strains were shown to be sensitive to most of the antibiotics including vancomycin, tetracycline, rifampicin, and erythromycin, while they were resistant to kanamycin and chloramphenicol. None of the strains showed any virulence (gelE, agg2, clyA, clyB, clyM) and antibiotic resistance genes (vanA, vanB, ermB, tetM, and aac(6')-le-aph(2 '')-la). In addition, all the strains were able to assimilate cholesterol, ranging between 25.2-64.1% and they exhibited variable adherence (19-36%) to Caco-2 cells. Based on the overall results of this in vitro study, four of the E. faecium strains isolated from human milk and colostrum can be considered as promising probiotic candidates; however, further in vivo evaluations are required.Öğe Production of concentrated whey beverage by osmotic membrane distillation: Comparative evaluation of feed effect on process efficiency and product quality(Elsevier Sci Ltd, 2021) Gulec, Haci Ali; Cinar, Kadir; Bagci, Ufuk; Bagci, Pelin OnsekizogluReconstituted whey powder (RCW), whey released after rennet-coagulation (PW) and microfiltration permeate of skim milk (IW) were used to produce concentrated beverage by osmotic membrane distillation (OMD). Effect of feed type on OMD performance and on final quality were evaluated. The use of IW not only promoted the greatest initial permeate flux but also reduced the operation time of OMD needed to reach 15.7 +/- 0.4 Brix, as compared with PW and RCW. Based on mineral and amino acid intake, the concentrated IW corresponded to 50 +/- 3% and 76 +/- 5% of equal amount of skim milk, respectively. While IW beverage was a good source of isoleucine, PW beverage provided adequate intake of valine besides leucine and isoleucine. Along with the better process performance, the use of IW in OMD resulted in obtaining plain concentrated whey beverage having comparable nutritive value with the PW and the RCW, and better clarity. (c) 2021 Elsevier Ltd. All rights reserved.Öğe Schiff-base ligands containing phenanthroline terminals: Synthesis, characterization, biological activities and molecular docking study(Pergamon-Elsevier Science Ltd, 2022) Ulucam, Guherguel; Bagci, Ufuk; Yilmaz, Aysen Suekinci; Yenturk, BusraThree new phenanthroline-derived ligands were synthesized by the Schiff base condensation method. The first ligand was the result of 1,10-phenanthroline-2-carboxyaldehyde reaction with 1,4-diaminobutane (L1). The other ligands were obtained 1,6-diaminohexane (L2) and 1,8-diaminooctane (L3) with the phenanthroline aldehyde in separate reactions. The structures of all ligands were elucidated using spectral techniques such as FT-IR, C-13 NMR, H-1 NMR and LC ESI/MS. The geometric properties of ligands such as bond lengths, bond angles, dihedral angles, electronic properties, HOMO and LUMO energies were calculated by using the Gaussian 09w programme. Ligands were optimized with B3LYP and 6-311++G(2d,p) basis set and NMR and FT-IR spectra were calculated. Experimental and theoretical spectrum data were compared. All of the ligands showed anti-bacterial activity against Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 11778. The anticancer activities of the ligands were also determined against human breast cancer (MCF7) and prostate cancer (DU145) cell lines. In addition, which conformation of the ligands was determined by the theoretical calculations. Docking studies of ligands with bovine serum albumin (BSA) were performed using Autock Tools 1.5.6 programme.
