Master Degree / Yüksek Lisans Tezleri

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Author: search.filters.author.Harsa, Hayriye Şebnem

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  • Master Thesis
    Bentonit Kullanılarak Sirke Durultma Prosesi Üzerine Araştırmalar
    (2025) Göktaş, İge Su; Harsa, Hayriye Şebnem
    Endüstriyel boyutta üretimi gerçekleşen sirke örneklerine (elma) bentonit ile berraklaştırma işlemi beş farklı dozda (C1: düşük, C2: düşük-orta, C3: orta, C4: yüksek ve C5: çok yüksek) bentonit ile uygulanmıştır. Berraklaştırma işlemi sonrasında nihai üründe, pH, renk, bulanıklık, protein ve fenolik madde analizleri gerçekleştirilmiştir. Elde edilen sonuçlar doğrultusunda, bentonit ile berraklaştırma işlemi sirke için etkili bir yöntem olduğunu göstermiştir. Orta-yüksek, yüksek ve çok-yüksek bentonit uygulamalarında sirkede en düşük bulanıklık değerleri elde edilmiştir. Protein değerlerindeki en düşük değer ise C4 ve C5 gruplarında yani yüksek ve çok yüksek gruplarda rapor edildi. Bu bulgular sirkedeki askıda katı maddelerin bentonit tarafından adsorbe edilerek, bulanıklığın giderilebileceğini göstermektedir. Ayrıca C4 ve C5 miktarlı bentonit uygulamalarında bile bulanıklık gideriminin sınırlı olduğu ve dalgalanmaların mevcut olabileceği gözlemlenmiştir.
  • Master Thesis
    Development of Probiotic Bar With Microencapsulated Probiotics
    (01. Izmir Institute of Technology, 2024) İriçağıl, Zelihan; Harsa, Hayriye Şebnem; Baysal, Ayşe Handan
    Bu çalışma, Saccharomyces boulardii CNCM-I745 ve Alkalihalobacillus clausii (N/R, O/C, SIN, T) gibi probiyotikleri mikroenkapsüle ederek, bu yararlı mikroorganizmaların stabilitesini ve canlılığını artırmayı amaçlayan bir probiyotik barın geliştirilmesini incelemektedir. Mikroenkapsülasyon, probiyotikleri koruyucu bir matris sağlayan lupin protein izolatı-ksantan gam-trehaloz kompleksi kullanılarak gerçekleştirilmiştir. Mikroenkapsüle edilmiş probiyotikler, glutensiz yulaf, hurma, fıstık ezmesi, kuru incir, ceviz, keten tohumu, tarçın ve tuz içeren bir bar formülasyonuna eklenmiştir. Nem içeriği, su aktivitesi, doku ve renk ölçümleri gibi fizikokimyasal analizler, barların kalitesini değerlendirmek için yapılmıştır. Ayrıca, probiyotiklerin canlılığını izlemek amacıyla 4°C'de 90 günlük bir depolama çalışması yürütülmüştür. Sonuçlar, mikroenkapsülasyonun probiyotiklerin stabilitesini ve hayatta kalma oranını önemli ölçüde artırdığını, canlı sayılarının depolama süresi boyunca 106 CFU/g üzerinde kaldığını ve Türk Gıda Kodeksi standartlarını karşıladığını göstermiştir. Özellikle, mikroenkapsüle edilmiş probiyotikler 90 günlük depolama süresince 1 log CFU/g'den az bir azalma gösterirken, serbest probiyotikler 3 log CFU/g'den fazla bir azalma göstermiştir. Çalışma ayrıca, probiyotiklerin in vitro gastrointestinal hayatta kalma oranlarını incelemiş ve mikroenkapsüle edilmiş probiyotiklerin simüle edilmiş mide ve bağırsak koşullarına karşı üstün direnç gösterdiğini ortaya koymuştur. Mikroenkapsülasyon süreci, depolama ve sindirim sırasında karşılaşılan zorlu çevresel faktörlerden koruyarak probiyotiklerin canlılığının korunmasını iyileştirmiştir. Bu araştırma, mikroenkapsülasyon tekniklerinin fonksiyonel gıdaların geliştirilmesindeki potansiyelini vurgulamakta ve yenilikçi, süt içermeyen probiyotik ürünler yaratma konusunda gıda endüstrisine değerli bilgiler sağlamaktadır.
  • Master Thesis
    Development of Aronia Based Vegan Nutritional Supplementation
    (01. Izmir Institute of Technology, 2024) Oruç, Yaren Tuğba; Harsa, Hayriye Şebnem
    Fonksiyonel gıdalar, özellikle Kovid-19 salgını sonrasında değişen yaşam standartlarıyla birlikte küresel tüketici kitlesi ve gıda sektörü için büyük önem kazanmıştır. Aronia melanocarpa, biyoaktif madde içeriği yüksek, antioksidan içeriği ve zengin besin değeri olan, tüm dünyada yaygınlaşan ve bununla birlikte Türkiye'de de giderek yaygınlaşma hızını artıran bir meyvedir. Gerçekleştirilen çalışmada Aronia melanocarpa'nın süper meyve olarak seçilmesi nedenlerinden olan bu zengin ve faydalı içerik ile insanlığın uğraşmak zorunda kaldığı büyük ve ciddi sorunlara etkili olabilecek bir fonksiyonel gıda ürünü tasarlamak amaçlanmıştır. Hazırlanan ürünlerin fiziksel, kimyasal, mikrobiyolojik, raf ömrü ve duyusal özellikleri analiz edilmiş ve bunun yanında Aronya smoothie ürünü in vitro sindirim ve ADE engelleyici aktivite açılarından da incelenmiştir. Bu fonksiyonel ürünün kırmızı mercimekten ekstrakte edilen protein tozu ile protein seviyesi artırılmış ve Aronya toz karışım ürünü için %23,7, Aronya smoothie ürünü için ise %3,74 protein içeriği elde edilmiştir. Aronya smoothie ürününe uygulanan in vitro sindirim sonrası ürünün fenolik ve antioksidan özelliklerinde artış gözlenmiştir. Aronya smoothie ürününün dünya genelinde uğraşılan ciddi kronik sağlık sorunlarından olan hipertansiyon ve kalp hastalıkları üzerinde olumlu etkisi bulunan mekanizma ADE engelleyici aktivitesi %22 olarak tespit edilmiştir. Duyusal analiz sonucunda Aronya smoothie ürününün genel kabul edilebilirlik puanı 3,65 elde edilmiştir.
  • Master Thesis
    Effect of Different Storage Conditions on the Stability and Functionality of Dairy Powders: a Case Study With Labneh Production
    (01. Izmir Institute of Technology, 2023) Gürkaynak, Dilara; Harsa, Hayriye Şebnem
    Dairy powders are frequently used in the food industry because of their distinctive nutritional profile and long shelf life. They are popular food ingredients due to their texturizing, emulsifying, and nutritional properties. Nevertheless, each product exhibits distinct attributes that confer unique functionalities to them. The purpose of this study is to comprehend the impact of storage temperature and time on the functionality and stability of dairy powders and their use in labneh production to see how storage conditions of an ingredient affect final product attributes. The study employs four different dairy powders, namely Milk Protein Concentrate (MPC85), Skim Milk Powder (SMP), Whey Protein Concentrate 80 (WPC80), and Whey Protein Concentrate 80 -S (WPC80S). The mentioned powders were subjected to storage conditions of 10 °C, 25 °C, and 37 °C for a duration of 4 months. Prior to subjecting them to any temperature conditions, the analysis on day zero (D0) was performed. On a monthly basis dairy powder properties were assessed using color analysis using the L*, a*, b* system, particle size distribution, Fourier Transform Infrared Spectroscopy (FTIR), water activity, and turbidity analysis. After 4 months, the powders were removed from their storage environments and used in labneh recipes. For each resulted labneh sample, various analytical techniques were employed, including Color analysis, Fourier Transform Infrared Spectroscopy (FTIR), Texture analysis, Rheology measurements, and Sensory evaluations. The findings indicate that alterations in the functionality of dairy powders may greatly impact the quality of the final product.
  • 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 Fermented Vegan Food Formulations With Improved Angiotensin-I Converting Enzyme Inhibitory (ace-I) Activity
    (01. Izmir Institute of Technology, 2022) Esen, Berna; Harsa, Hayriye Şebnem
    Veganism has become popular in recent years and the demand for vegan products is increasing, especially due to the positive effects of plant-based diets on health. Since veganism can be defined as a diet or lifestyle that does not support the consumption of any animal food, protein-rich legumes occupy a large place in the daily diet of vegans. The health-promoting potential of probiotics in various forms has been recognized for years, and one of these health-promoting properties is their antihypertensive effect. In this context, the aim of this thesis is to develop some vegan food formulations, such as vegan mayonnaise-based salad dressings prepared using chickpea aquafaba and plant-based milk alternative (PBMA) fermented using lactic acid bacteria (LAB), showing antihypertensive effect. Microbiological, and quality characteristics and antioxidant properties of the formulations were determined. In addition, proteolytic activity and angiotensin-I converting enzyme inhibitory (ACE-I) activity experiments were carried out to control the antihypertensive properties of salad dressings. As a result, there are 107 CFU/ml bacteria in the final products. The quality characteristics of the formulations were compared with the literature. Consequently, the ACE-I activity of PBMA was enhanced by LAB fermentation and vegan mayonnaise was enriched with these high-value ingredients.
  • Master Thesis
    Functionalization of a Vegan Snack With Antimicrobial Edible Coating
    (01. Izmir Institute of Technology, 2022) Atik, Hande; Harsa, Hayriye Şebnem
    Pomegranate peel is usually considered as a waste of fruit by many people, but it has quite high content of antioxidant, phenolic and antimicrobial compounds. The objective of this thesis is to observe the effect of edible film in vegan snack bar containing of dried fruits, nut and to functionalize the snack bar with enrichment of protein and antimicrobial content. The edible film was composed of 8% w/v of lentil protein extract, 15% w/w of pomegranate peel depends on protein content, 2% of pectin as a stabilizer and 0.5% of glycerol as a plasticizer. Application of coating was carried out by dipping method. Then, the coated vegan snack bar was dried at 40oC for 16 hours. The coated and uncoated bars were investigated in different conditions as 30% RH at 25 oC and 75% RH at 35 oC for 90 days. Optical properties, texture, total phenolic content, sensory, microbial and water activity analysis were determined to evaluate the impact of edible coating incorporation onto surface of the bar. The results showed that the coated bars have been preserved better than uncoated ones in terms of prevention of color change, microbial and textural properties, phenolic content and moisture loss in both conditions.
  • Master Thesis
    Modulating Akkermansia Muciniphila by Probiotics for Obesity Management
    (Izmir Institute of Technology, 2021) Kamber, Aslıhan; Harsa, Hayriye Şebnem; Bulut Albayrak, Çisem
    The 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, 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.