Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Modulating Akkermansia Muciniphila by Probiotics for Obesity Management(Izmir Institute of Technology, 2021) Kamber, Aslıhan; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; Bulut Albayrak, Çisem; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03. Faculty of EngineeringThe aim of this thesis is to investigate the potential of lactic acid bacteria (LAB) having probiotic properties to trigger Akkermansia muciniphila as anti-obesity candidate. Artisanal strains of LAB were evaluated in terms of stability in gastrointestinal conditions, mucin/mucus non-utilization properties, growth in the presence of mucin, adhesion to the mucin/mucus layer, biofilm formation, lactate production abilities, antimicrobial properties, HT-29 cell binding and mucin/mucus thickness increment abilities. Among 40 strains, 17 of LAB including 6 olive isolates were selected for their tolerance to gastrointestinal conditions and analyzed for further abilities e.g., mucin promotion potential. Most of them (13 of the 17 bacteria) remained viable in the range of 106-108CFU/mL in the simulated gastric juice, and these bacteria continued their viability in the range of 105-107 CFU/mL in the simulated intestinal fluid. Besides, 6 reference and 7 L. bulgaricus isolates did not utilize the mucin and showed no or negligible growth in the presence of mucin. Additionally, 13 of the 17 bacteria adhered to mucin layer with variable degree of binding between 41.03-65.37%. Furthermore, variable degree biofilm formation efficiencies can also support their existence and adhesion to intestinal cells. Varying amounts of lactate by 7 LAB were produced (6.51-18.17 g/L) and this ability is another important criteria for supporting mucus pathway. All those strains adhered to HT-29 cell line and they showed significant increase in mucin thickness by comparing the control. L. plantarum C47 and Lactobacillus AK50 isolates were selected as the antiobesity prototype candidates for their desirable attributes.Master Thesis Development of Functional Chocolate Using Gamma-Amino Butyric Acid Producer Probiotic: Prominent To Alleviate Anxiety Disorder(Izmir Institute of Technology, 2019) Özer, Merve; Sezgin, Efe; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; Sezgin, Efe; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe purpose of this study was screening of four probiotics to investigate for their gamma-aminobutyric acid producing capabilities. Lactobacillus rhamnosus NRRL B- 442 strain has been selected for its maximum gamma-aminobutyric acid concentration. In this study, a new chocolate product has been developed by incorporation of probiotic cells; stability of the probiotics was improved by microencapsulation by water-in-oil emulsion technique using whey-pullulan complex. Survival rates of microencapsulated and free-cells of probiotic bacteria in chocolate have been compared. Probiotic counts were found as 6.75 log CFU/g and 7.20 log CFU/g in chocolate, for encapsulated and free-cells, respectively, at the end of 60 days. High cell counts and increased cell resistances were remained at 4oC when compared at 25oC, in chocolate samples. Furthermore, probiotics did not affect the physical, chemical and sensory properties of chocolate, whereas the texture analysis showed an increase in the hardness of free-cell in chocolate bacteria on the 0th and 60th day. Survival rate of microencapsulated bacteria in chocolate samples was observed at higher percentage 87% than free-cell bacteria e.g. 75% during simulated in-vitro analysis. Consequently, Lb. rhamnosus with the highest GABA producing capability may provide insight for patients having an anxiety disorder, since this strain has been thought as having a therapeutic effect. A new functional food model was developed for “Gut- Brain Axis” phenomena since the chocolate could be accepted as a good carrier for probiotics.Master Thesis Developing Probiotic Lozenges To Improve Oral Health(Izmir Institute of Technology, 2019) Elvan, Menşure; Baysal, Ayşe Handan; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; Baysal, Ayşe Handan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRecently, there is a great need to overcome complaints about oral health from children, mental and physically handicapped people who are inadequate in oral hygiene and after chemotherapy of cancer patients. With reduced body resistance, opportunistic Streptococcus mutans and Candida albicans in the mouth become dominant, causing disruption of oral health. Therefore, the effect of lactic acid bacteria on pathogens was investigated in order to protect oral health with the thesis study. Lactobacillus pentosus NRRL-B 227 was determined among the probiotic bacteria tested for this purpose and its activity on the pathogen Streptoccocus mutans ATCC 25175 and Candida albicans DSMZ 5817 was found in broth microdilution, agar overlay and planktonic culture assays except disc diffusion test. To reduce the number of pathogens in oral microflora, lozenges containing L. pentosus were developed. Three different lozenges with encapsulated and free bacteria and control lozenge were produced, kept at different temperatures; 4⁰C and 25⁰C. No significant decrease in viability of the encapsulated probiotic strain after lozenge production and storage at 4°C was observed, the probiotic amount in the lozenge initially counted as 7.84 log CFU/g, while 7.73 log CFU/g at the end of 3 months shelf life. However, lozenges stored at 25⁰C probiotics lost their vitality after one month. Additionally, lozenges containing free bacteria have lost viability rapidly. Color and water activity were observed differently in the formulations (p <0.05). The formulations maintained their microbiological safety during storage. Lozenge with L. pentosus NRRL-B 227 has a significant potential for improving oral health and provides an alternative to the diversification of products containing probiotics.Master Thesis Developing a Guide of Bioinformatic Database for Probiotic Products(Izmir Institute of Technology, 2019) Yılmaz, Melike; Sezgin, Efe; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; Sezgin, Efe; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRecently, probiotic use has rapidly expanded, as they have potential health effects for microbiota to protect homeostasis in the human body. Bioinformatics is generally defined as collecting and analysing biological data. Establishing a bioinformatic system for probiotics, would have a potential to emphasize the beneficial impacts for human health, while enabling cross examination on diseases and products. In this study, new information has been collected about probiotics based on in vitro, in vivo, clinical trials and meta-analysis to develop a comprehensive guide. Metaanalyses of sixteen and seventeen randomized, controlled trials of S. boulardii (Sb) against diarrhea reported pooled relative risks of 0.51 (95% CI [0.40-0.64]) in adults and 0.55 (95% CI [0.42-0.72]) in children, respectively. These results demonstrated that Sb was effective for preventing and treating different types of diarrhea in adult and children patients. An in silico gene expression study conducted in Tecnico Lisboa* comparing Sb probiotic and non-probiotic Saccharomyces cerevisiae (Sc) strains showed transcription regulation differences in 26 genes. An in silico pipeline that was used as the basis for a new query in the ProBioYeastract database was developed. A cross-strain promoter analysis, comparing Sb CNCM I-745 and Unique28 strains with Sc S288C strain showed that the expression of 26 probiotic-related genes was predicted to be controlled by different transcription factors in probiotic vs non-probiotic strains. Among the evaluated six selected genes, a gene involved in biofilm formation, aggregation, and adhesion, EFG1, was found to be up-regulated in Sb CNCM I-745 compared to Sc BY4741.Master Thesis Development of Functional Food Ingredient as a Solution for Protein-Energy Malnutrition; an Amino Acid Source With Low-Phenylalanine Content(Izmir Institute of Technology, 2015) Akın, Hilal; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyCasein glycomacropeptide (CGMP) is one of the whey protein which constitutes 12-20% of whey proteins approximately. It has various functional and biological activities. Such as growth-promoting effects on bifidobacteria, suppression of gastric secretion and the inhibition of viral or bacterial adhesion to intestinal epithel cells, inactivation toxins of Escherichia coli and Vibrio cholerae, inhibition adhesion of cariogenic bacteria with use in toothpastes. It also has good foaming emulsifying agent properties. The objective of this thesis was to develop a new functional food ingredient suitable for use by individuals with Phenylketonuria (PKU) that causes protein malnutrition. In line with this objective, CGMP was used as a protein source. It was isolated from caprine whey by ultrafiltration process. This process was applied with different parameters to obtain CGMP with high purity and yield. Protein fractions and Phenylalanine and tyrosine contents of CGMP isolates were determined by RP-HPLC. Some compositional analysis was carried.Master Thesis Investigation of Biocompatibility of Calcium Phosphate Based Materials and Cements(Izmir Institute of Technology, 2014) Karataş, Özlem; Harsa, Hayriye Şebnem; Çiftçioğlu, Muhsin; Çiftçioğlu, Muhsin; Harsa, Hayriye Şebnem; 03.02. Department of Chemical Engineering; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyCalcium phosphate cements (CPCs) have been extensively investigated due to their excellent biocompatibility, osteoconductivity, potential resorbability in dentistry and orthopedics. They have numerous advantages over other calcium phosphate-based materials. The CPC precursor powders were prepared in the initial stage of this work. Tetracalcium phosphate (TTCP) powders coded as TTCP-1 (obtained from H3PO4 and CaCO3) and TTCP-2 (obtained from NH4H2PO4 and CaCO3) were prepared by heat treatment of the calcium and phosphate source mixtures at 1350°C. Brushite powders were produced by aqueous chemical methods. A series of CPCs (HA cements) were prepared by using the TTCP-1 and brushite powders which were mixed with 0.2 M and 0.3 M phosphate buffer solutions at three different solid/liquid ratios (2.4, 2.7 and 3.2 g/ml) with three different HA initial seed contents (3%, 1.5% and 0.0 wt% ). The setting times of CPCs were determined to be in the 3.5-24 minute range. The phase structure and surface morphology of the cements and precursor powders were characterized by XRD and SEM. XRD analysis of powders revealed the presence of the characteristic TTCP and brushite peaks. XRD analysis also indicated that all cement samples were composed by HA phase with different crystallinity and other phases were not detected. Rod and plate-like hydroxyapatite crystals were observed in the SEM micrographs of all CPCs. Cytotoxicity testing was performed using the MTT (3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide) assay to determine the number of viable cells in the presence of powders and HA cements. Cytotoxicity results indicated that brushite powder caused sharp decreases in cell viability at the end of 24, 48 and 72 hours at all powder extract concentrations. TTCP-1 and TTCP-2 powders unlike brushite had no toxic effect with cell viability values over 74 %. Almost all CPCs prepared in this work had no cytotoxic effects.Master Thesis L[+]-Lactic Acid Purification From Fermentation Broth Using Ion Exchange Resins(Izmir Institute of Technology, 2002) Polat, Zelal; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyLactic acid exists in two optically active form, D(-) and L(+)-lactic acid. It has been used in food, leather, textile, pharmaceutical and cosmetic industries. Moreover, L(+)-lactic acid constitutes the raw material for the production of poly-L-lactic acid which is used in biomedical applications.The aim of this study was to recover and purify the microbially produced L(+)-lactic acid from the fermentation media efficiently and economically. Among the various downstream operations, ion exchange chromatography was used since it is highly selective and yields a low cost product recovery within a short period of time. The additional goals were to investigate the end product purity, to obtain new data on the adsorption/desorption behaviours of lactic acid and to investigate the applicability of the system for industrial usage. In this project, Lactobacillus casei NRRL B-441 was used for the production of L(+)-lactic acid from whey by a 12 hours fermentation process at pH 5.5 and 37 oC. The product concentration was 50 g/l with 100% L(+)-lactic acid content. Then, a suitable resin with high sorption capacity and rapid equilibrium behavior was selected. The selected resin was Dowex marathon WBA, a weakly basic anion exchanger in OH form. It reached the equilibrium state in 15 minutes. The batch sorption experiments were done at pH 7.0 and 30 oC and sampling was continued for 20 hours. Furthermore, the effect of temperature and pH was investigated and their influence was found to be unimportant. All the adsorption/desorption experiments were applied both to model lactic acid and to biomass free fermentation broth. The ion exchange equilibria of lactic acid and L(+)-lactic acid in fermentation broth on Dowex marathon WBA were explained by the Langmuir isotherm. The maximum exchange capacity (qm) for model lactic acid was 0.25 g La/g wet resin, while L(+)-lactic acid in fermentation broth has a qm value of 0.04 g La/g wet resin. The equilibrium loading and exchange efficiency of L(+)-lactic acid in fermentation broth were reduced as a result of competition by other ionic species. The competing ions inhibit the binding of L(+)-lactic acid to the free sites of ion exchanger. Moreover, column operations were applied to recover sorbed lactic acid from the ion exchanger. 2.0 M HCl was found to be a suitable eluting agent to recover the bound L(+)-lactic acid with a flowrate of 1 ml/min at ambient temperature. About 95 % of bound L(+)-lactic acid was recovered from Dowex marathon WBA.Master Thesis The Preparation and Characterization of Hydroxyapatite Bioceramic Implant Material(Izmir Institute of Technology, 2000) Çiftçioğlu, Rukiye; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe use of hydroxyapatite (HA) powders and ceramIcs as a biomaterial was investigated in this work. A commercial HA powder was used for the preparation of HA ceramics and the adsorption of Bovine Serum Albumin (BSA) onto HA has been investigated.The powder and the sintered ceramics were characterized by TGA, DT A, Optical Microscopy, Microhardness Tester, XRD, and FTIR.The sintering studies have shown that it was possible to prepare porous ceramics above 800°C and dense ceramics at 1200-1250°C range.The HA powder lost about 5.5% by weight during heat treatment up to 1000DC and 80% of this weight loss is due to adsorbed water.The particle size of the powder was determined to be submicron whereas the grain sizes of the 1250°C sintered ceramic was in the 1-5 /l um range.A maximum Vickers Hardness of 585 Hv was determined for the 1250°C sintered 97.2% dense ceramic.XRD patterns of the powder and the 1250°C sintered ceramic were identical and almost phase pure. A small CaO peak was detected in the samples which was believed to be remnants of the powder preparation process.The adsorption of BSA onto HA has been studied as a function of time, protein concentration, pH, ionic strength, and HA solids loading. Adsorption experiments were also conducted with commercial alumina and zirconia ceramic powders. Uptake curves have shown that the adsorption process was almost completed in less than ten minutes Adsorption isotherms 'at different pH ( 4.5-7.4) have been obtained and analyzed using the Langmuir model. The Langmuir parameters qm ( maximum amount of protein adsorbed, mg BSA/g HA) and K' (affinity constant, mllmg BSA) have been calculated. qm decreased from 119 to 61.3 with the increase in pH from 4.7 to 7.4. A maximum of 46.1 for K' was determined at pH.5.6 and K' had the lowest value of 3.5 at pH.7.4. Electrostatic attractions were held responsible for the K' maximum at pH.5.6 since HA and BSA surfaces are oppositely charged. The presence of a considerably high amount of BSA adsorption on the HA surface at pH.4.7 where the protein should have close to zero net charge was attributed to hydrophobic effects. The amount of adsorption at equilibrium in the 4.5-5.8 pH range was determined to be twice of that in the 6-8 pH range. Almost 100% of the protein was recovered with a HA solids loading of 750 mg HA/50 ml solution at equilibrium for an initial BSA concentration of I mg BSA/ml solution.Master Thesis Biosortion of Nickel (ii) by Using Waste Baker's Yeast(Izmir Institute of Technology, 2001) Özdemir, Peruze; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology3 Biological methods for removing heavy metals are in competition with chemical and physical techniques such as precipitation, ion exchange, electrochemical treatment and evaporative recovery, especially, when the concentration of the heavy metal ion is low, between 1.0 and 100 mg/L. In order to qualify for industrial applications, biosorbents have to be produced at low cost. The use of biomass from various production stages; e.g. from the pharmaceutical or the food industries, is one way to minimize the costs. This study is concerned with the binding of nickel ions onto waste biomass of Saccharomyces cerevisiae genus, obtained from the food industry. Since the biomass employed is a waste material, biosorption process described in this study may represent a cheap alternative to conventional methods.Biomass cell walls, consisting mainly of polysaccharides, proteins and lipids, offer many functional groups which can bind metal ions such as carboxylate, hydroxyl, phosphate and amino groups.The objective of this study was to investigate the adsorption of nickel on wastebaker.s yeast as a function of several factors, i.e. pretreatment, pH, temperature, biomass concentrations and initial metal concentrations, in order to determine the optimum adsorption conditions of a batch process.Pretreatment of waste yeast biomass using sodium hydroxide, formaldehyde, nitric acid and ethanol decreased the sorption of nickel (II) ions compared with live biomass. Optimum initial pH for nickel (II) ions was 5.0 at the optimum temperature of 25o C. The uptake values increased with the increasing initial nickel (II) ion concentrations up to 150 mg/L. The optimum biomass concentration for this process was determined as 1.0 g/L.The biosorption isotherms were developed at various initial pH and temperature values. The equilibrium values were expressed with the Langmuir model while nickel sorption did not fit the Freundlich plot. The Langmuir parameters qmax (14.30 mg/L) and b (0.0069 L/mg) have been calculated."qmax" increased from 7.8 to 14.30 mg/L with the increase in pH from 3.0 to 5.0. Similar trend was observed for the "b" values; an increase from 0.0025 to 0.0069 L/mg were obtained when the pH of the solution was raised from 3.0 to 5.0. Both Langmuir model parameters were found to be the highest values at pH 5.0 which is consistent with the results of the optimization studies as described above.Temperature also affected the phase equilibria of nickel (II)/S.cerevisiae system.The highest capacity for biosorption system was obtained at 25o C with the qmax and b values of 14.3 mg/L and 0.0069 L/mg at pH 5.0, respectively. The enthalpy change for the biosorption process have been evaluated by using the Langmuir constant "b", which is related to the energy of adsorption. Nickel (II) biosorption is considered to be an exothermic process since low binding occurs when the temperature increases from 25 to 45o C.The uptake of nickel (II) ions by the yeast biomass was also investigated with respect to time under optimum operating conditions. Biosorption kinetics were rapid within the first few minutes. After the initial rapid uptake, further biosorption by yeast cells continued slowly and reached an equilibrium after 2 hours at all pH values of 3.0, 4.0 and 5.0. On the other hand, the rate of adsorption was found to be the fastest at pH 5.0 with an initial rate of around 3.59 mg Ni (II) / g-min.Master Thesis Immobilization of Lipase From Candida Rugosa on Hydrophobic and Hydrophilic Supports(Izmir Institute of Technology, 2001) Öztürk, Banu; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aim of this study is to find the optimum conditions for the immobilization of Candida rugosa lipase and also to select the most suitable support maximizing the immobilized enzyme yield under these optimum conditions.Prior to the immobilization studies, optimum working conditions of soluble Candida rugosa lipase were investigated. Candida rugosa lipase expressed maximum activity in pH 6.5 phosphate buffer with 1.0 M NaCl solution at 30 0C. Indeed, lipase was fully active between 4 and 37 0C. Under these conditions, activity of free lipase was 12.2 U/mg enzyme.Immobilization studies were carried out under constant temperature and stirring rate. Immobilization of lipase on hydrophobic support, octyl-sepharose, was very rapid and the equilibrium was reached in 10 minutes. Immobilized enzyme ratio was maximized by the use of pH 7.0 phosphate buffer with 1.0 M NaCl at 37 0C. Also, optimum solid-liquid ratio was found to be 0.1 when 1 ml support was added to 9 ml of enzyme solution. Effect of enzyme loading on lipase immobilization on octyl-sepharose was investigated at two different temperatures. At 20 0C and in the specified range of enzyme concentration (0.25-75 mg/ml), the experimental data fitted well to the linear isotherms with a C value of 138.2. Also, at 4 0C, results were similar and the experimental data could be expressed with the linear isotherm with a C value of 209.1. Under these conditions, activity of immobilized enzyme was 410 U/ml hydrated support.In the case of immobilization on hydrophilic support, chitosan, the reaction was much slower and the amount of the immobilized enzyme was maximized at the end of 24th hour. Optimum conditions of immobilization were determined as pH 6.5 and 20 0C. In this case, addition of salt decreased the immobilization and, therefore, low ionic strengths favored immobilization. Again, optimum solid-liquid ratio was found to be around 0.1 when the 1 ml support was added to 9 ml. of enzyme solution. The effect of enzyme loading was investigated at 20 0C and in the specified range of concentration, data fitted well to the Langmuir isotherm where the constants were calculated to be qm.200 U adsorbed enzyme/ml hydrated support and K. 72.5 U/ml solution.The storage stability of chitosan immobilized lipase was investigated at 4 0C under two different conditions. When immobilized lipase was kept dry for 25 days, 50 % of the initial activity remained. However, if the same lipase was kept in phosphate buffer of pH 6.5, activity loss was only 10 % after a period of 2 months. Complementary work was also carried out to find the differences in the behavior of free and chitosan immobilized lipase against different substrates. The results showed that the presence of 33 % olive oil and 45.5 % corn oil in substrate yielded the maximum activity for free and chitosan immobilized lipases, respectively.