Master Degree / Yüksek Lisans Tezleri

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

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Language: search.filters.language.enSubject: search.filters.subject.Food additives

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  • Master Thesis
    Organosolv Treatment for Prebiotic Oligosaccharide Production From Agro-Food Waste
    (01. Izmir Institute of Technology, 2020) Temelli, Nuran; Büyükkileci, Ali Oğuz
    Xylooligosaccharides (XOS), which are among the prebiotic carbohydrates, are produced by hydrolysis of xylan in the lignocellulosic agricultural and food wastes. Production processes, such as autohydrolysis and enzymatic hydrolysis following alkali extraction, have some limitations. In this study, it was aimed to develop a process that could overcome those limitations. Corn cob was used as the model biomass and it was pretreated with organosolv. The organosolv pretreatment conditions (solvent concentration, time, temperature, catalyst addition) were adjusted to maximize the lignin removal from the biomass while recovering xylan in the biomass. Delignification could be achieved with 40%-50% lignin removal, and around 85% of the xylan was retained in the biomass. The effect of the organosolv conditions on XOS formation was investigated by the hydrolysis of the pretreated biomass using three commercial xylanases. The organosolv and the enzymatic hydrolysis conditions influenced the XOS formation. The maximum XOS production was observed with the biomass pretreated at 150°C for 1 h with 70% ethanol and 0.1 M MgO. That biomass was enzymatically hydrolyzed at 70°C with 0.6 U/ml xylanase and 70% of the xylan was converted to XOS yielding a hydrolysate containing 9.5 g/l XOS. With the process developed in this study, the need for the application of concentrated alkaline and acidic solutions can be eliminated since the xylan extraction step is not needed. In addition to that, the formation of carbohydrate degradation products can be avoided due to the lower treatment temperatures compared to autohydrolysis. These can simplify the downstream processing following the production of XOS and minimize the environmentally harmful chemical wastes. In this process, a liquid stream rich in lignin and a solid stream rich in cellulose were released. Following a biorefinery concept, these streams can potentially be valorized together with the xylan, so that lignocellulosic wastes can have an added value. This study will be followed by related projects on XOS purification and determination of the prebiotic potential of XOS. In addition to that, the process developed will be tested on other lignocellulosic wastes.
  • Master Thesis
    Development of Functional Food Ingredient as a Solution for Protein-Energy Malnutrition; an Amino Acid Source With Low-Phenylalanine Content
    (Izmir Institute of Technology, 2015) Akın, Hilal; Harsa, Hayriye Şebnem
    Casein glycomacropeptide (CGMP) is one of the whey protein which constitutes 12-20% of whey proteins approximately. It has various functional and biological activities. Such as growth-promoting effects on bifidobacteria, suppression of gastric secretion and the inhibition of viral or bacterial adhesion to intestinal epithel cells, inactivation toxins of Escherichia coli and Vibrio cholerae, inhibition adhesion of cariogenic bacteria with use in toothpastes. It also has good foaming emulsifying agent properties. The objective of this thesis was to develop a new functional food ingredient suitable for use by individuals with Phenylketonuria (PKU) that causes protein malnutrition. In line with this objective, CGMP was used as a protein source. It was isolated from caprine whey by ultrafiltration process. This process was applied with different parameters to obtain CGMP with high purity and yield. Protein fractions and Phenylalanine and tyrosine contents of CGMP isolates were determined by RP-HPLC. Some compositional analysis was carried.
  • Master Thesis
    Efficacy of Natural Antimicrobials on Food-Borne Pathogens and Their Applications
    (Izmir Institute of Technology, 2008) Eroğlu, Erdal; Soyer Dönmez, Ferda
    Microbial contamination of food products increases the risk of food-borne infections and intoxications. In recent years, more studies have been performed for development of natural alternatives to control the growth of pathogenic microorganisms in food rather than chemical origin. In the present study, natural antimicrobial agents from different sources, activated lactoferrin-(ALF), rosemary extract-(RE), jenseniin-G (JG) and natamycin-(NA) were used.The antimicrobial activity of agents (ALF-RE-JG) and their combinations against L. monocytogenes, E. coli O157:H7 and S. Enteritidis, and NA against A. niger and P. roquefortii was tested. These antimicrobials, found effective in vitro, applied also on meat and cheese samples. The minimum inhibitory concentrations (MIC) of ALF, RE and JG against pathogens were determined via disc diffusion and microtiter plate growth assay. Dipping method was applied on meat samples to test the efficacy of antimicrobials. MIC of NA was determined via disc diffusion assay. NA was applied on cheese samples to test the efficacy against both molds by dipping method.The data from microtiter well plate assay showed that ALF is effective on three pathogens. Rosemary extract inhibited only growth of L. monocytogenes and JG did not show any significant activity on the growth of same pathogens. RE enhanced the activity of ALF on E. coli O157:H7. Neither individual activity nor synergistic activity was determined by disc diffusion assay. The data from disc diffusion assay revealed that the effective NA concentration on both molds was 750 ppm. Some of dipping applications on both meat and cheese displayed promising results.