Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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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, SultanIn 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 Modulating Akkermansia Muciniphila by Probiotics for Obesity Management(Izmir Institute of Technology, 2021) Kamber, Aslıhan; Harsa, Hayriye Şebnem; Bulut Albayrak, ÇisemThe 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; Harsa, Hayriye Şebnem; Sezgin, EfeThe 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 HandanRecently, 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.