Master Degree / Yüksek Lisans Tezleri

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

Browse

Filters

2007 - 200912010 - 201922020 - 20232

Settings

Scopus Q: search.filters.scopusQuartile.N/ASubject: search.filters.subject.Probiotics

Search Results

Now showing 1 - 5 of 5
  • Master Thesis
    Investigation of Probiotic Properties of Cold Brewed and Fermented Cold Coffee Beverage
    (01. Izmir Institute of Technology, 2023) Semiz, Şevval; Baysal, Ayşe Handan
    The goal of the project was to produce a functional probiotic fermented cold brewed coffee that is perapered with medium roasted, grinded Colombian Arabica beans with patented probiotic yeast Saccharomyces boulardii that can survive in human gastrointestinal conditions. With pasteurization of the product, safe fermentation environment and long shelf life was achieved. Coffee brew samples were prepared with different techniques to understand the effects of fermentation and glucose fortification to fermentation media on coffee chemistry, microbiota and sensory characteristic. One of the three coffee brews was only pasteurized (P), one of them fermented (F) and the other was fermented with glucose (FG). The cold brewing and fermentation were performed respectively at 22 °C and 30 °C for 24 hours. The brewed samples were pasteurized before fermentation at 65 °C for 30 minutes. Each sample was examined during their 120 days shelf life (at +4 °C). Although the probiotic yeast enabled fermentation in coffee, it did not survive after the first week. Pasteurization was successful, so pathogen growth was not detected in any of the samples during their shelf life. While FG was evaluated as undrinkable, the other samples gave positive results in terms of sensory. Caffeine, chlorogenic acid, and ethanol levels were significantly altered during shelf life. This is the first study in which chemical, microbiological and sensory analyzes of cold coffee that was brewed via cold immersion method, pasteurized and fermented with patented S. boulardii yeast during shelf-life were conducted, and will lead to new studies in this field.
  • Master Thesis
    Developing Spreadable Peanut Butters Incorporated With the Encapsulated Potential Psychobiotic Lactococcus Lactis C19.1 Strain
    (01. Izmir Institute of Technology, 2023) Akkuş, Zeynep Aysun; Harsa, Hayriye Şebnem; Arslan Tontul, Sultan
    In recent years, the partially processed food market has increased, partly due to the demand for fresh-cut or dried products. However, there is an increasing demand for foods enriched with physiologically active ingredients such as probiotics and prebiotics. From the nutrional point view, these two functional factors, have created a new market area for fruit and snack products. Peanuts have high nutritional value (24% protein, 45% fat and 13% fiber) as well as high amounts of thiamine and niacin). It is also known to reduce the risk of prostate, liver, colon and lung cancer and stress-related diseases. In this study, as a model bacteria Lactococcus lactis C19.1 strain isolated from Turkish cottage cheese has been impregnated with peanut and cashew nut butter after encapsulation. In the selection of the Lactococcus lactis strain, porbiotic and anti-stress properties were considered. To increase the viability of the strain, the encapsulation was carried by whey protein-xylan complex as the wall material. After encapsulation, the probiotic strain was added to the peanut and cashew nut butter formulation. In addition, in order to determine the encapsulation efficiency, it was impregnated to the butters the free cell form. The results revealed that encapsulation increased the shelf life stability of the psychobiotic cell. The shelf life of the peanut butters containing free cell of L. lactis was determined as 30 days that of 45 days in encapsulated cell containing samples. In addition, in vitro analyzes revealed that encapsulation protected probiotic cells in simulated gastrointestinal system and, the viability was between 106 – 107 CFU/g. However, the viability rate was found to be 105 in fort he free cell containing samples after digestion test. Cashews and peanut butters containing encapsulated cell came to the fore, as 105 CFU/g remained below the 106 CFU/g, which is the condition of being probiotic.
  • 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; Harsa, Hayriye Şebnem; Sezgin, Efe
    The 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; Harsa, Hayriye Şebnem; Baysal, Ayşe Handan
    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
    Isolation, Characterization, Determination of Probiotic Properties of Lactic Acid Bacteria From Human Milk
    (Izmir Institute of Technology, 2007) Yavuzdurmaz, Hatice; Harsa, Şebnem
    Probiotics mean live microorganisms that have beneficial effects on their host.s health. Although probiotic strains can be isolated from many sources; for human applications the main criteria is being human origin.Breast milk is an important nutrient source for neonates. Lots of studies showed that this fluid has beneficial effects on the health of neonates. One reason of being beneficial is explaining by the microflora of human breast milk including beneficial lactic acid bacteria.In this study, isolates were identified by biochemical and molecular characterization and also probiotic properties of lactic acid bacteria, isolated from human milk were investigated.Three of the isolates were observed as potential probiotic. Two of them are bacilli and the other is cocci. These isolates showed resistance to stomach pH (pH 3,0), tolerance against 0,3% bile concentration and antimicrobial activity against Salmonella thyphimurium CCM 5445, Escherichia coli O157:H7 NCTC 129000 and Escherichia coli NRRL B-3008. After investigation the probiotic properties of these isolates, they were identified by biochemical characterization techniques and molecular identification by using amplification and restriction fragment length polymorphism (RFLP) of 16S ribosomal DNA (rDNA) and 16S sequencing. Two lactobacilli were identified as Lactobacillus oris and Lactobacillus fermentum. In the light of this study, it is observed that, human milk is a source of potential probiotic strains.