Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 69Citation - Scopus: 89Pectinase Enzyme-Complex Production by Aspergillus Spp. in Solid-State Fermentation: a Comparative Study(Elsevier, 2012) Heerd, Doreen; Yeğin, Sırma; Tarı, Canan; Fernandez Lahore, MarceloA comparative evaluation of three Aspergillus species according to their pectinase production in solid-state fermentation was performed. Solid-state fermentation offers several potential advantages for enzyme production by fungal strains. Utilization of agricultural by-products as low-cost substrates for microbial enzyme production resulted in an economical and promising process. The pectinolytic enzyme activities of two Aspergillus sojae strains were compared to a known producer, Aspergillus niger IMI 91881, and to A. sojae ATCC 20235, which was re-classified as Aspergillus oryzae. Evaluation of polymethylgalacturonase and polygalacturonase activity was performed as well as exo- vs. endo-enzyme activity in the crude pectinase enzyme-complex of the mentioned strains. Furthermore, a plate diffusion assay was applied to determine the presence and action of proteases in the crude extracts. A. sojae ATCC 20235 with highest polymethylgalacturonase activity and highest polygalacturonase activity both exo- and endo-enzyme activity, is a promising candidate for industrial pectinase production, a group of enzymes with high commercial value, in solid-state fermentation processes. Beside the enzymatic assays a protein profile of each strain is given by SDS-PAGE electrophoresis and in addition species-specific zymograms for pectinolytic enzymes were observed, revealing the differences in protein pattern of the A. sojae strains to the re-classified A. oryzae. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Article Citation - WoS: 17Citation - Scopus: 23Pasteurization of Verjuice by Uv-C Irradiation and Mild Heat Treatment(Wiley, 2019) Kaya, Zehra; Ünlütürk, SevcanVerjuice is a highly acidic juice and more prone to yeast spoilage. In this study, the efficacy of individual and combination processes of UV-C irradiation (UV) and mild heat treatment (MH) for pasteurization of verjuice were assessed. Saccharomyces cerevisiae (NRRL Y-139) was selected as the target microorganism and kinetic parameters for MH, UV, and combined UV + MH inactivation treatments were determined. The UV treatment alone at a UV dose of 0.57 J/cm(2) (energy of 2.30 J/mL), provided only 0.54 +/- 0.02 log CFU/mL reduction of S. cerevisiae. In contrast, the combined treatment (UV + MH2) substantially reduced the number of S. cerevisiae in verjuice, 5.16 +/- 0.24 log CFU/mL reduction was achieved at 0.25 J/cm(2) UV dose (energy of 1.01 J/mL) and 51.25 +/- 1.47 degrees C. The percentage of synergism for the UV + MH inactivation of S. cerevisiae in verjuice was maximized at 51.25 degrees C (50.79% of synergistic effect). Inactivation kinetics of S. cerevisiae was best described by Weibull model with the smallest RMSE and AIC values. D value was decreased from 13.66 to 1.94 min when UV was combined with mild heating. The results showed that UV-C light assisted by mild heat treatment can be a potential alternative to thermal pasteurization of verjuice. Practical applications Fruit juices are prone to spoilage by yeasts, molds, and some acid-tolerant bacteria. Saccharomyces cerevisiae is a heat resistant spoilage microorganism and found in some spoiled juices. Thermal pasteurization is widely used for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. This study illustrated that the combined UV-C light assisted by mild heat treatment can deliver the required microbial reduction in verjuice. The synergistic effect of two processing methods is suggested for controlling the growth of spoilage microflora of fruit juices.Article Citation - WoS: 14Citation - Scopus: 15A Portable Microfluidic Platform for Rapid Determination of Microbial Load and Somatic Cell Count in Milk(Springer, 2019) Düven, Gamze; Çetin, Barbaros; Kurtuldu, Hüseyin; Gündüz, Gülten Tiryaki; Tavman, Şebnem; Kışla, DuyguMicrofluidics systems that have been emerged in the last 20years and used for processing the fluid in a microchannel structure at microliter levels are alternative to the conventional methods. The objective of the study is to develop a microfluidic platform for determination of the microbial load and the number of somatic cells in milk. For this purpose, a polydimethylsiloxane (PDMS) chip with a channel size of 300mx60m was produced. Cells/bacteria labeled with fluorescent stain in milk were counted with the proposed microfluidic platform and the results were compared with the reference cell concentration/the bacterial counts by conventional method. It was found that our platform could count somatic and bacterial cells with an accuracy above 80% in 20min run for each analysis. The portable overall platform has an overall dimension of 25x25x25 cm and weighs approximately 9kg.Article Citation - WoS: 39Citation - Scopus: 45Host Genetics of Cytomegalovirus Pathogenesis(Frontiers Media S.A., 2019) Sezgin, Efe; An, Ping; Winkler, Cheryl A.Human cytomegalovirus (HCMV) is a ubiquitous herpes virus (human herpes virus 5) with the highest morbidity and mortality rates compared to other herpes viruses. Risk groups include very young, elderly, transplant recipient, and immunocompromised individuals. HCMV may cause retinitis, encephalitis, hepatitis, esophagitis, colitis, pneumonia, neonatal infection sequelae, inflammatory, and age-related diseases. With an arsenal of genes in its large genome dedicated to host immune evasion, HCMV can block intrinsic cellular defenses and interfere with cellular immune responses. HCMV also encodes chemokines, chemokine receptors, and cytokines. Therefore, genes involved in human viral defense mechanisms and those encoding proteins targeted by the CMV proteins are candidates for host control of CMV infection and reactivation. Although still few in number, host genetic studies are producing valuable insights into biological processes involved in HCMV pathogenesis and HCMV-related diseases. For example, genetic variants in the immunoglobulin GM light chain can influence the antibody responsiveness to CMV glycoprotein B and modify risk of HCMV-related diseases. Moreover, CMV infection following organ transplantation has been associated with variants in genes encoding toll-like receptors (TLRs), programmed death-1 (PD-1), and interleukin-12p40 (IL-12B). A KIR haplotype (2DS4+) is proposed to be protective for CMV activation among hematopoietic stem cell transplant patients. Polymorphisms in the interferon lambda 3/4 (IFNL3/4) region are shown to influence susceptibility to CMV replication among solid organ transplant patients. Interestingly, the IFNL3/4 region is also associated with AIDS-related CMV retinitis susceptibility in HIV-infected patients. Likewise, interleukin-10 receptor 1 (IL-10R1) variants are shown to influence CMV retinitis development in patients with AIDS. Results from genome-wide association studies suggest a possible role for microtubule network and retinol metabolism in anti-CMV antibody response. Nevertheless, further genetic epidemiological studies with large cohorts, functional studies on the numerous HCMV genes, and immune response to chronic and latent states of infection that contribute to HCMV persistence are clearly necessary to elucidate the genetic mechanisms of CMV infection, reactivation, and pathogenesis.Conference Object Can Post-Mastectomy Radiation Therapy Be Omitted in T1-2 Clinically Node-Negative Breast Cancer Patients With a Positive Sentinel Lymph Node Biopsy?(Springer, 2019) Dinh, Kate; Soran, Atilla; Işık, Arda; McAuliffe, Priscilla; Diego, Emilia; Sezgin, Efe; Johnson, RonaldBackground/Objective: The AMAROS trial demonstrated that both axillary radiation and axillary lymph node dissection (ALND) provide excellent locoregional control in patients with clinically node-negative T1-2 breast cancers and a positive sentinel lymph node biopsy (+SLNB). In that study, 18% of patients underwent total mastectomy (TM). We evaluate survival outcome of TM patients who do not require additional axillary treatment after identification of a +SLNB.Article Citation - WoS: 260Citation - Scopus: 293Randomized Trial Comparing Resection of Primary Tumor With No Surgery in Stage Iv Breast Cancer at Presentation: Protocol Mf07-01(Springer, 2018) Soran, Atilla; Özmen, Vahit; Özbaş, Serdar; Karanlık, Hasan; Müslümanoğlu, Mahmut; İgci, Abdullah; Johnson, Ronald; Sezgin, EfeThe MF07-01 trial is a multicenter, phase III, randomized, controlled study comparing locoregional treatment (LRT) followed by systemic therapy (ST) with ST alone for treatment-na < ve stage IV breast cancer (BC) patients. At initial diagnosis, patients were randomized 1:1 to either the LRT or ST group. All the patients were given ST either immediately after randomization or after surgical resection of the intact primary tumor. The trial enrolled 274 patients: 138 in the LRT group and 136 in the ST group. Hazard of death was 34% lower in the LRT group than in the ST group (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.49-0.88; p = 0.005). Unplanned subgroup analyses showed that the risk of death was statistically lower in the LRT group than in the ST group with respect to estrogen receptor (ER)/progesterone receptor (PR)(+) (HR 0.64; 95% CI 0.46-0.91; p = 0.01), human epidermal growth factor 2 (HER2)/neu(-) (HR 0.64; 95% CI 0.45-0.91; p = 0.01), patients younger than 55 years (HR 0.57; 95% CI 0.38-0.86; p = 0.007), and patients with solitary bone-only metastases (HR 0.47; 95% CI 0.23-0.98; p = 0.04). In the current trial, improvement in 36-month survival was not observed with upfront surgery for stage IV breast cancer patients. However, a longer follow-up study (median, 40 months) showed statistically significant improvement in median survival. When locoregional treatment in de novo stage IV BC is discussed with the patient as an option, practitioners must consider age, performance status, comorbidities, tumor type, and metastatic disease burden.Article Citation - WoS: 1Citation - Scopus: 1Temperature and Glycerol Formation: a Proposal To Explain the Causal Relationship Based on Glycolytic Enzyme Activities(American Society for Enology and Viticulture, 2019) Büyükkileci, Ceylan; Batur, Ayşem; Büyükkileci, Ali Oğuz; Hamamcı, HalukMost yeast strains produce glycerol in larger quantities when cultivated at higher temperatures, which likely explains why red wines contain higher amounts of glycerol than white wines. In this work, we used a kinetic and thermodynamic approach to suggest a mechanistic explanation for this phenomenon. We began with a glycolytic model of the kinetics of the individual enzymes. The effects of temperature and ethanol on the apparent kinetics of individual enzymes were then determined and incorporated into the model. The activation energy for each enzyme was determined with the Arrhenius equation. The enzymes in the upper part of the glycolytic pathway were found to be more dependent on the temperature than those in the lower part. The model, as improved by these changes, could qualitatively simulate the ethanol and glycerol production curves and the production of more glycerol at higher temperatures. We propose that the differences in the temperature dependence of the enzymes around the glycerol branch are the reason for glycerol accumulation at higher temperatures.Article Citation - WoS: 11Citation - Scopus: 12Characterization of the Self-Assembly and Size Dependent Structural Properties of Dietary Mixed Micelles by Molecular Dynamics Simulations(Elsevier Ltd., 2019) Tuncer, Esra; Bayramoğlu, BesteThe bile salts and phospholipids are secreted by the gallbladder to form dietary mixed micelles in which the solvation of poorly absorbed lipophilic drugs and nutraceuticals take place. A comprehensive understanding of the micellization and structure of the mixed micelles are crucial to design effective delivery systems for such substances. In this study, the evolution of the dietary mixed micelle formation under physiologically relevant concentrations and the dependence of structural properties on micelle size were investigated through coarse grained molecular dynamics simulations. The MARTINI force field was used to model cholate and POPC as the representative bile salt and phospholipid, respectively. The micellization behavior was similar under both fasted and fed state concentrations. Total lipids concentration and the micelle size did not affect the internal structure of the micelles. All the micelles were slightly ellipsoidal in shape independent of their size. The extent of deviation from spherical geometry was found to depend on the micellar POPC/cholate ratio. We also found that the surface and core packing density of the micelles increased with micelle size. The former resulted in more perpendicular alignments of cholates with respect to the surface, while the latter resulted in an improved alignment of POPC tails with the radial direction and more uniform core density.Article Citation - WoS: 19Citation - Scopus: 21Physicochemical and Antimicrobial Properties of Oleoresin Capsicum Nanoemulsions Formulated With Lecithin and Sucrose Monopalmitate(Humana Press, 2019) Akbaş, Elif; Söyler, U. Betül; Öztop, Mecit HalilOleoresin capsicum (OC) is an extract of chili pepper containing the active agent capsaicin. In this study, OC-loaded nanoemulsions were prepared by microfluidization and stabilized with sucrose monopalmitate (SMP) and lecithin. The difference in size and distribution of droplets determined the nanoemulsion behavior mainly due to the interaction of emulsifiers between oil and aqueous phase. The hydrophilic interaction between SMP and aqueous phase and the hydrophobic interaction between lecithin and oil phase were monitored with NMR relaxometry. OC nanoemulsion fabricated with SMP showed the best transparency with smallest droplet size (around 34nm) and stable with glycerol after 28days at ambient storage. Lecithin containing nanoemulsions showed improved bioactivity as showing antioxidant (0.82mg DPPH/L) and antimicrobial (3.40 log for Escherichia coli and 4.37 log for Staphylococcus aureus) activity. Finally, results have important implications to determine the appropriate formulation conditions for OC with food-grade surfactants to be used in pharmaceuticals and food industry.Article Citation - WoS: 12Citation - Scopus: 16Control of Lactic Acid Bacteria in Fermented Beverages Using Lysozyme and Nisin: Test of Traditional Beverage Boza as a Model Food System(Wiley, 2018) Sözbilen, Gözde Seval; Korel, Figen; Yemenicioğlu, AhmetThe objective of this study was to increase quality and limited shelf-life of boza (3–15 days), a traditional Balkan origin fermented beverage using lysozyme (LYS) and/or nisin (NIS). For this purpose, the effectiveness of NIS, LYS and LYS:NIS combinations was first tested in a broth medium at 4 °C for 3 weeks on Lactobacillus plantarum, one of the frequently isolated lactic acid bacteria in boza. Stability of LYS and NIS in boza, their effects on LAB counts, and chemical and sensory properties of boza were then evaluated during cold storage at 4 °C. Results of LAB counts as well as pH, d- and l-lactic acid, and titratable acidity measurements showed that LAB in boza containing NIS (250 μg g−1) or LYS:NIS (500:250 μg g−1) could be controlled without reducing LAB counts below 6 log CFU mL−1 during 2 weeks shelf-life. In contrast, LYS (500 μg g−1) alone could not control LAB in boza to delay its acidic spoilage. Positive effects of NIS and LYS:NIS application on quality of boza were also proved with sensory analysis by panelists and e-nose measurements. This work showed that use of natural GRAS agents in preservation of fermented beverages containing probiotic LAB is possible without affecting their characteristic aroma and flavour.