Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Effects of Commercial Non-Saccharomyces Yeasts on Quality of Wines Produced From Emir Grapes(Izmir Institute of Technology, 2023) Hacısali̇hoğlu, Di̇la; Korel, Fi̇gen; 01. Izmir Institute of TechnologyBu çalışmada non-Saccharomyces ticari maya türlerinin Emir üzümünden elde edilecek şarapların üretiminde kullanılarak, şarabın kimyasal ve organoleptik özelliklerine etkisini incelemek, henüz bu konuda yerel üzümlerle ilgili kısıtlı bilgi barındıran literatüre katkıda bulunmak ve sektörde bu ürünlerin kullanılması için şarap üreticilerine yarar sağlamak amaçlanmıştır. Bu amaçla Metschnikowia pulcherrima, Torulaspora delbrueckii, ve Metschnikowia pulcherrima / Torulaspora delbrueckii karışımı içeren ticari aktif mayaların her biri Saccharomyces cerevisiae ile sıralı fermantasyon yapılmıştır. Uygulanan 4 ay olgunlaşma süreci sonunda, şaraplarda kimyasal (alkol, asit, pH, yoğunluk, uçar asit, indirgen şeker, toplam/serbest SO2), renk ve HS-SPME-GC/MS ile uçucu bileşik analizleri yapılmıştır. Metschnikowia pulcherrima / Torulaspora delbrueckii karışımı ile fermente edilmiş şarap duyusal analizde en iyi sonucu almıştır. Non-Saccharomyces mayaların daha düşük alkol oluşturduğu ve yalnızca Saccharomyces cerevisiae ile fermente edilen şaraptan farklı olarak şarabın aroma kompleksitesine katkıda bulunan izobütanol, izoamil oktanoat ve oktanoik asit ürettiği gözlemlenmiştir. Şaraplarda yağlılık hissi gibi olumsuz özellik kazandıran dodekanoik asit oluşumu ise yalnızca Saccharomyces cerevisiae ile fermente edilen şaraplarda tespit edilmiştir. Çalışma sonucunda, non-Saccharomyces mayaların aktif kuru maya olarak Saccharomyces cerevisiae ile sıralı fermantasyonuyla şarap kalitesi üzerine olumlu etkileri olduğu belirlenmiştir.Master Thesis Investigation of Applicability of Uv-Light Emitting Diodes (uv-Leds) as an Alternative Technology in Pasteurization of Cold-Pressed and Newly Formulated Mixed Beverage(Izmir Institute of Technology, 2022) Baykuş, Gökçen; Ünlütürk, Sevcan; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aims of this thesis were to evaluate the cold pressing technique for juice extraction and to evaluate whether the cold pressed mixed beverage can be pasteurized with ultraviolet light emitting diodes (UV-LEDs) using E. coli K12 as the target microorganism. Initially, the physical, chemical and optical properties of cold pressed juice (CPJ) were compared with juice extracted by centrifugal juicer (CDJ). The CPJ was then exposed to UV-LEDs simultaneously and sequentially and the microbial inactivation was evaluated. Besides, barrier technologies have been tried to increase the UV-LED inactivation effect. It has been found that the juice yield performance of the cold pressing technique is better than the centrifuge method. The total phenolic content of the CDJ and CPJ was 922 ± 0.01 mg GAE/L, and 867.25 ± 0.01 mg GAE/L, respectively. However, DPPH radical scavenging activity of both beverages were not significantly different. The use of UV-LEDs in simultaneous or sequential mode could not achieve a 5-log reduction in pertinent microorganism required as part of HACCP mandated by US Federal regulations for juice issued by the Food and Drug Administration (FDA). However, filtration and addition of ginger juice revealed that the inactivation efficiency of UV-LEDs increased in highly turbid juice reaching to 3.65 ± 0.218 log10 CFU/ml. In conclusion, this study showed that UV-LEDs used simultaneously at different wavelengths may have the potential to be used in turbid cold press juice pasteurization when combined with different barrier technologies.Master Thesis Investigation of the biological health potency of fig stalk waste pectin for colon cancer cell growth and intestinal glucose absorption(Izmir Institute of Technology, 2022) Yemenicioğlu, Ahmet; Güleç, Şükrü; Başer, Filiz; Güleç, Şükrü; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyHigher intake of dietary fiber is correlated with reduced obesity-related disorders such as cardiovascular diseases and diabetes, improved gut health, and protection against colorectal cancer. Pectin comes from plant cell walls and is mainly composed of galacturonic acid units branched with neutral sugars that provide bioactive and functional properties. Pectin has long been appreciated in the food industry due to its viscous structure and gelling properties. Dietary pectin as a soluble fiber is linked with cancer and metabolic health. Anti-cancer activity of pectin is promising in multiple types of cancer in humans and animals by inducing cellular apoptosis and inhibiting tumor metastasis. Soluble dietary pectin regulates blood glucose levels, sparking interest in diabetes prevention and treatment. Fig stalk waste was used as an unconventional pectin source in the present study, providing a promising green option. The health benefit of fig stalk waste pectin (FSWP) was investigated in terms of colon cancer cell growth and intestinal glucose absorption. The inhibitory effects of FSWP on colon cancer Caco-2 cells were further confirmed with cell cycle analysis and apoptotic cell death. Intestinal glucose absorption was modeled with Caco-2 enterocyte uptake and transport systems. FSWP inhibited 2-deoxyglucose uptake into Caco-2 cells and reduced glucose absorption as a food ingredient in the intestinal transport system. Taken together, FSWP has promising bioactivity against colon cancer and could be used as a functional food additive due to its inhibitory effect on intestinal glucose absorption.Master Thesis Investigation of the Usability of Radiochromic Films for Determination of Dose Uniformity of Food Surface in Uv-C Treatment(Izmir Institute of Technology, 2022) Ünlütürk, Sevcan; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe microbial inactivation efficiency of UV light is dependent on product shape and surface morphology on non-planar food surfaces. Since every point of the product is not exposed to the same level of UV light, the efficiency decreases. In addition, during UV light illumination, blind spots may occur, and sufficient inactivation cannot be achieved. So, it is essential to determine UV fluence (dose) applied to surfaces. Actinometry, biodosimetry and mathematical techniques are used to evaluate UV fluence on solid surfaces and in liquid foods. In this study, use of radiochromic films (RCFs) integrated with a computer vision system (CVS) based on image analysis is proposed as an alternative method to evaluate UV fluence on food surfaces. For this purpose, the color change of RCFs on non-planar surfaces exposed to different UV intensity and exposure time was correlated with UV fluence. The results were compared with actinometric and radiometric measurement techniques. Experimental results have been tested and verified on real food surfaces such as apples. It was revealed that there is a linear correlation between the color change of RCF and UV fluence. The maximum UV fluence that could be determined using RCF at 254 nm was approximately 60 mJ/cm2. It was found that films were stable up to 15 days at room and refrigerated conditions. The shape of the apples resulted in different UV fluence distribution profiles on the surface. As a result, it has been demonstrated that RCFs can be successfully used to determine UV fluence on sample surfaces.Master Thesis Development of High Stability Antioxidant Emulsions Based on Citrus and Fig Pectins(Izmir Institute of Technology, 2022) Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this thesis, stability and antioxidant activity of olive oil-in-water emulsions prepared with citrus pectin (CPEC) and pectins extracted from two fig cultivars (Sarılop: FPECn and Siyah Orak: FPECc) were evaluated in the presence of green tea (GTE) and grape seed extracts (GSE), and a basic monomeric flavonoid, (+) catechin (CAT). The emulsion stabilities of FPECn and FPECc between 0.125 and 1% (w/v) were comparable to those of CPEC. Control olive oil-in-water emulsions with 0.5% CPEC, FPECn or FPECc prepared without the addition of polyphenols lost 29 to 36% of their initial emulsion stability only within 1 day. The addition of GSE at 0.25 or 0.5% caused a considerable increase in the stability of emulsions prepared with CPEC at 0.5% (less than 10% loss in emulsion stability within 14 days) while GTE caused only a limited increase in the stability of CPEC emulsions. The CAT is the only polyphenol that caused significant increases in the stability of all pectin emulsions. In contrast, both GTE and GSE showed almost no effect in stability of FPECn and FPECc emulsions. The polyphenol added emulsions were characterized for their droplet size, zeta potential and viscosities. The CAT and GSE added emulsions showed significantly higher total phenolic content and antioxidant activity than GTE added emulsions during 14 days of storage. This thesis clearly showed that GSE and CAT stabilized CPEC emulsions, and CAT stabilized FPECn or FPECc emulsions have a great potential to develop novel antioxidant olive oil based functional foods.Master Thesis Fabrication of Colorimetric Ph Indicator Films by Electrospinning(Izmir Institute of Technology, 2022) Eroğlu, Ahmet Emin; Bayramoğlu, Beste; Bayramoğlu, Beste; Eroğlu, Ahmet Emin; 03.08. Department of Food Engineering; 04.01. Department of Chemistry; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe trend in the food packaging industry evolves towards innovative packaging materials as biosensors, which record the status of the product and can warn the consumer. The logic behind the colorimetric pH biosensor is that they provide the essential information about food visually by detecting change in pH. Anthocyanins are natural color pigments susceptible to pH change. Purple basil is rich in anthocyanins. In this study, ultrasound-assisted extraction was used for the extraction of dry purple basil. The processing conditions were optimized by response surface methodology (RSM) in terms of the total monomeric anthocyanin content and the increase in green intensity with pH. Electrospinning is a nanofiber fabrication operation used to encapsulate sensitive bioactive compounds for the production of intelligent sensing system. Polycaprolactone (PCL) films incorporating different purple basil extract (PBE) concentrations were fabricated by electrospinning procedure for the usage of colorimetric pH-indicator films as intelligent packaging. The most beadles and uniform nanofibrous mats were obtained when the spinning conditions were V=20 kV and Q=0.4 mL h-1for 10% (w v-1) PCLsolutions containing 0.4% and 0.6% (w v-1) PBE. The average fiber diameters in these films were 178.59±52.92 nm and 235.39±92.46 nm, respectively. The films gave promising results with regards to their use as colorimetric pH-indicator films. The time required to observe a visible color change (ΔE) in these films was only 4-5 s. The ΔE values between all successive pH’s were higher than 2, which is detectable by an inexperienced observer. Keywords: Anthocyanin, Purple Basil, Ultrasound-Assisted Extraction, Response Surface Methodology (RSM), Electrospinning, Colorimetric pH-indicator Films.Master Thesis Development of Novel Pet Food Involving Drying Step(Izmir Institute of Technology, 2022) Güleç, Şükrü; Güleç, Şükrü; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyMost of the pet parents prefer dry petfood since it is easy to portion, has longer open-shelf life and doesn`t have an unappealing smell compared to wet petfood. However, wet petfood more closely resembles the fresh meat that pets crave. It helps maintaining hydration and digestion since it includes a high water content. In the petfood industry, it is an open new area to produce dry petfood that can be easily rehydrated and turned into a wet product to provide the benefits of both dry and wet petfood. Considering current food products in the market, a pasta production line can be shown as a good example of manufacturing such products. It consists of dry powder and wet material. Having this analogy in mind, a novel textured wet petfood development was investigated. A Microwave vacuum dryer is used as a novel drying technology in petfood industry. In laboratory trials, die plates of different sizes were tested and the effect of surface area on rehydration was investigated. In pilot plant trials, different raw materials were tested and their effect on the process and on the rehydration time were evaluated. Results showed that the increase in the surface area had a significant effect on the rehydration time. Also, it was observed that the use of blood plasma powder affected the formulation positively and the rehydration negatively. The products made by using poultry meal which were cooled twice after cooking, showed the highest efficiency by causing the least formation of fines during cutting.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.