Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Investigation of Probiotic Properties of Cold Brewed and Fermented Cold Coffee Beverage(01. Izmir Institute of Technology, 2023) Semiz, Şevval; Baysal, Ayşe HandanThe 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, 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.