Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Disinfection of Liqued Egg Products by Using Uv Light(Izmir Institute of Technology, 2007) Atılgan, Mehmet Reşat; Ünlütürk, Sevcan; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe application of UV treatment to continuous flow of liquid egg products is the initial study among the others. The objective of this study was to investigate the efficiency of UV-C radiation as a non-thermal pasteurization process for liquid egg products (LEPs). The outcomes of this study were evaluated from the rheological, biodosimetric and inactivation efficiency points of view. The results pertaining to rheological characterization, physical and optical measurements of the fresh and pasteurized LEPs indicated that liquid whole egg (LWE) and liquid egg white (LEW) showed Newtonian behavior within the range studied. Liquid egg yolk (LEY) exhibited pseudoplastic and time independent behavior in temperature ranges from 4 C to 25 C. But its rheological behavior was affected at pasteurization temperature and showed thixotropy and time dependent. The biodosimetric study based on the UV treatment of LEPs by using collimated beam apparatus pointed out that the best reduction was achieved in liquid egg white (LEW) when the fluid depth and UV dose were 0.153 cm and 98 mJ/cm2, respectively. Maximum inactivation was 0.675-log CFU/ml in liquid egg yolk (LEY) and 0.316-log CFU/ml in liquid whole egg (LWE). The kinetics of UV inactivation of E.coli in LEPs was found nonlinear. Our results emphasize that UV-C radiation can be used as a pre-treatment process or combined with mild heat treatment to reduce the adverse effects of thermal pasteurization of LEPs. The efficacies of short wave ultraviolet light (UV-C) as a non-thermal process for LEW were investigated in the continuous flow UV reactor based on the result derived from the biodosimetric study. Maximum 0.2 log reduction was achieved after 5 cycle of operation. The efficiency of the UV light treatment in continuous flow UV reactor was found to be lower compared to bench-top studies. This is attributed to the problems caused by inefficient design of UV chamber. Results of these work showed that the UV reactor was designed poorly to supply enough UV irradiation exposure for all the fluid elements in the system. Redesigning of the system was suggested.Master Thesis Uv Disınfection of Some of the Fruit Juices(Izmir Institute of Technology, 2009) Hakgüder, Bengi; Ünlütürk, Sevcan; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAlthough UV-C irradiation is used in the pasteurization of certain liquids, the application to white grape juice is not sited in the literature. Besides there are a few studies about the inactivation of naturally grown microorganisms by using UV-C treatment. The objective of this study was to determine the effect of UV-C treatment on the inactivation of Escherichia coli K12 inoculated into white grape juice and naturally grown microorganisms in the fresh squeezed orange juice. Also, the effect of UV light on the colors of the products was determined. The data were evaluated considering the properties of the juices. Results of microbiological analysis of white grape juice showed that, maximum log reduction was more than 5-log CFU/mL at a UV dose of 75.04 mJ/cm2 when the inoculation rate was 5.73 (l20.114) log CFU/mL. Although a 5-log reduction requirement of FDA was satisfied with white grape juice, maximum log reduction for the naturally grown microorganisms in orange juice was only 1.76-log CFU/mL even if the sample was subjected to UV dose of 144.36 mJ/cm2. Color analysis demonstrated that orange juice color was not affected from the treatment. For white grape juice, increased UV dose caused a decrease in a* value indicating slightly more green region.Also, increased intensity and sample depth had a pronounced effect on b* value of the juice showing yellow region. As a conclusion, UV-C light can be used as an alternative technique in processing of white grape juice. Combination of UV-C with other techniques is suggested to increase the microbiocidal efficiency in orange juices.