Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Baysal, Ayşe HandanPublisher: search.filters.publisher.Izmir Institute of Technology

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Now showing 1 - 6 of 6
  • Master Thesis
    Dynamics and Bioinformatis of Microbial Spoilage Ecology of Kefir
    (Izmir Institute of Technology, 2022) Memon, Ayşe; Sezgin, Efe; Baysal, Ayşe Handan; Baysal, Ayşe Handan; Sezgin, Efe; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this study, it was aimed to characterize the microbiological properties, bacterial composition, and microbial stability of 5 different commercial milk kefir beverage products during refrigerated storage. In order to determine the microbiological load and compositions, total mesophilic aerobic bacteria, yeast and molds, lactic acid bacteria, Lactobacilli, Lactococci, total coliforms, and E.coli were investigated by cultural conventional analysis for milk kefir beverages. According to the obtained data, microbiological and hygienic characteristics of the samples were found acceptable. The bacterial load of the kefir beverage samples ranged between 7.086 and 8.794 log10 cfu.ml-1 for viable total aerobic mesophilic bacteria (TAMB), 6.792 and 8.382 og10 cfu.ml-1 for lactic bacteria (LAB), <10 and 6.322 log10 cfu.ml-1for Lactobacillus, 5.857 and 8.146 log10 cfu.ml-1 Lactococcus, 5.176 and 7.218 log10 cfu.ml-1 for yeasts, negative for molds, coliform bacteria and negative for E. coli. Principal component analysis (PCA) of the compounds separated the kefir beverages according to the storage time and kefir brands. Strong relationship were found between storage time and PC1 and between kefir brands and PC2. To date, information on microbial properties, bacterial composition, and constancy of commercial kefir is scant, and to the best of our knowledge, this is the first research to contribute information on kefir beverages in microbial properties, bacterial composition, and their stability during refrigerated storage by evaluating Fourier Transform Infrared Spectroscopy (FTIR) spectra analysis and Bioinformatics besides cultural conventional analysis.
  • Master Thesis
    Environmental Factors Influencing Bacterial Biofilm Formation and Inactivation
    (Izmir Institute of Technology, 2020) Üreğen, Mert; Özçivici, Engin; Baysal, Ayşe Handan; Baysal, Ayşe Handan; Özçivici, Engin; 03.01. Department of Bioengineering; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Objective of this study was to evaluate effect of UV-C radiation (0, 1.16 and 3.21 kJ/cm2), pomegranate (Punica granatum) seed essential oil (PGEO) and lemon (Citrus lemonum) plant essential oil (CLEO) on decontamination of Candida albicans, Listeria monocytogenes, Staphylococcus aureus and Esherichia coli O157:H7 biofilms formed at +4°C and 20°C on polystyrene, stainless steel and glass surfaces. After 16, 32 and 64 sec UV-C treatment 0.24 log CFU/cm2, 1.61 log CFU/cm2, 1.59 log CFU/cm2 reductions were achieved in the numbers of C. albicans biofilms formed at 20°C on polystyrene. In the numbers of S. aureus biofilms formed at 20°C on polystyrene 0.99 log CFU/cm2, 1.9 log CFU/cm2, 3.91 log CFU/cm2 reductions were obtained after 16, 32 and 64 sec UV-C treatments, respectively. In general C. albicans biofilm formed at 20°C on stainless steel was found as the most UV-C resistant biofilm. CLEO inhibited the growth of C. albicans, L. monocytogenes and S. aureus at MIC values of 186 µg/ml, 103.5 µg/ml and 103.5 µg/ml, respectively. The results of the study showed that UV-C radiation and CLEO can be used as an anti-biofilm agent to control or to prevent biofilm formation of foodborne bacterial pathogens. It was suggested that UV-C radiation and CLEO treatments have potential as a biofilm control interventions for the food industry.
  • 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 Technology
    Recently, 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
    Differentiation of Filamentous Fungi by Polymerase Chain Reaction (pcr) and Fourier Transform Infrared (ftir) Spectroscopy
    (Izmir Institute of Technology, 2017) Güngör, Sinem; Baysal, Ayşe Handan; Baysal, Ayşe Handan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Fourier transform infrared (FTIR) spectroscopy is considered to be a rapid, reliable, sensitive, and a cost-effective technique, which could be used as an efficient tool for microorganism identification. Since bio-molecules, such as lipids, carbohydrates, and nucleic acids, have their own unique ‘vibrational’ fingerprints and characteristic functional groups, which correspond to specific infrared light frequencies, FTIR spectrum obtained for any compound gives the information on the unique ‘fingerprint’. The objective of this study was to investigate the ability of FTIR spectroscopy for differentiating different species of filamentous fungi. In this study, Erkence cultivar olives which were collected from different orchards were used for different fungal strain isolation. The fungi isolates were grown on Malt Extract Agar (MEA) and Czapek Yeast Agar (CYA) at room temperature of 25ºC for 10 days. 15 different genera and 53 species were identified by using Polymerase Chain Reaction (PCR) and characterized in terms of DNA sequencing. FTIR spectroscopy was applied to 71 species as a novel technique to identify fungi. 18 pre-defined species that were collected fom previous studies, were also used for FTIR spectroscopy investigation. Statistical analysis of the data was performed by using a principal component analysis (PCA). FTIR spectroscopy provides a potentially powerful approach to differentiate filamentous fungi.
  • Master Thesis
    Real-Time Pcr as a Molecular Tool for the Enumeration of Probiotics in Commercial Products
    (Izmir Institute of Technology, 2016) Öz, Ödül; Arslanoğlu, Alper; Baysal, Ayşe Handan; Baysal, Ayşe Handan; Arslanoğlu, Alper; 03.08. Department of Food Engineering; 04.03. Department of Molecular Biology and Genetics; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Quantitative Real-Time PCR (qPCR) assays targeting the 16S rDNA was developed as a genus and species specific detection tool for Bifidobacterium and Lactobacillus, and Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus acidophilus LA-5, respectively. Standard curves were established to quantify these probiotic bacteria. The linear regression of standard curves indicated high correlations between the log numbers of pure probiotic culture cells and the Ct values. The assay had a high efficiency and the limit of detection was estimated to be 1.54 ng DNA (corresponding to 104 cells). Results show that qPCR method may be very useful as a rapid, sensitive and specific tool for detecting and quantifying B. animalis subsp. lactis BB-12 and L. acidophilus LA-5 in probiotic supplements. FTIR spectroscopy was used for the first time to determine the ratios of different microorganisms in commercial probiotic supplements. FTIR analysis was also performed for the pure probiotic cultures of B. animalis subsp. lactis BB-12 and L. acidophilus LA-5. Results obtained in this study showed that FTIR spectroscopy is potentially a rapid method for determining probiotic cell components and their ratios in the supplements and verification their detection and identification.
  • Master Thesis
    Microbiological Characterization of 'hurma Olives Grown in Karaburun Peninsula
    (Izmir Institute of Technology, 2013) Karslı, Gözde Seval; Baysal, Ayşe Handan; Baysal, Ayşe Handan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Erkence variety olive (Olea europea L.) cultivar growing in the Aegean Region of Turkey is a naturally black olive. Debittered Erkence variety called "Hurma" olive is an unusual olive type which is characterized by the sweet taste of its fruit. This olive which is grown mainly in Karaburun Peninsula differs from other varieties since it ripens on the tree losing its bitterness caused by phenolic compounds especially oleuropein. Thus, Hurma olives can be directly consumed from the tree without a further debittering process to make them edible. Total aerobic mesophilic microorganisms, lactic acid bacteria (LAB), Enterobacteriacaae, Pseudomonadaceae, Staphylococcaceae-Micrococcaceae, moulds and yeasts were enumerated in the olive drupes, leaves and orchards' air of Erkence and Gemlik cultivars during the maturation period. Moreover, bacterial microflora of Hurma olive fruit, leaf and orchards' air were characterized in terms of DNA sequencing. Microbial loads of naturally debittered "Hurma" olive were higher when compared with Gemlik olive's and non-debittered Erkence variety olive's. But no Pseudomonadaceae, Staphylococcaceae-Micrococcaceae and LAB were detected in all samples. Bacterial microflora genera of Hurma olive comprised of Bacillus, Pantoea, Acinetobacter and Pseudomonas while the other samples have also similar bacterial genera. The common genus found in all samples was Bacillus. Besides, more diversified genera were obtained from phylloplane and air microflora of Erkence variety olive orchard was substantially similar to bacterial phylloplane of leaf. This is the first study about microbiological characterization of Hurma olive type and will lead up to new studies about it.