Assesment of the efficiency of UV light emitting diodes (UV-LEDS) for fruit juice pasteurization
Akgün, Merve, author.

Assesment of the efficiency of UV light emitting diodes (UV-LEDS) for fruit juice pasteurization

Akgün, Merve, author.

Yazar Ek Girişi
Akgün, Merve, author.

Fiziksel Tanımlama
xvi, 154 leaves: illustrarions, charts;+ 1 computer laser optical disc.

The objectives of this thesis are to evaluate the application of ultraviolet light emitting diodes (UV-LEDs) with various wavelengths for pasteurization of cloudy (CAJ) and clear apple juices (AJ), to assess the disinfection efficiency of combined UV-LED irradiation and mild heat (UV-LED+MH) treatments, to investigate the effect of individual and combined processes on the activity of enzyme, physicochemical and microbiological quality of AJ, to determine the shelf life of UV-LED irradiated juice during storage, to reveal the reactivation potential of target microorganism (E. coli K12) in juice medium with different optical properties, and to elucidate the mechanism of microbial inactivation by UV-LEDs. 280/365 nm UV-LED irradiation assisted by mild heat at 55ºC and 15 min exposure time enhanced the inactivation of E. coli K12 and polyphenoloxidase and satisfied the 5-log reduction pasteurization criterion in apple juice. UV-LED+MH treatment extended the shelf life of CAJ from 3 to 30 days and increased its total phenolic content. However, the color properties were slightly affected by ultraviolet treatment. Subsequent photoreactivation of E. coli K12 after inactivation by UV-LEDs was observed in both CAJ and AJ. Contrarily, dark repair was repressed at 4ºC and 22ºC, furthermore, a decrease in the survival ratio was recorded in both medium. It was revealed that the damage of DNA repair enzymes and the proteins that form the outer cellular membrane of bacteria was highly induced by UV-C light at 280 nm. Additionally, the bactericidal effect of 365 nm (UV-A) wavelength was attributed to enhanced production of reactive oxygen species (ROS) resulting in oxidative damage to cellular lipids, proteins and DNA. The combination of these two wavelengths provided more efficient disinfection than that of UV-C light used alone. UV-LED irradiation assisted by mild heat has a potential to be used as an alternative technique to traditional thermal pasteurization process for juice products. This study leads to useful information for the future design of UV-LED treatment systems.

Konu Başlığı
Fruit -- Preservation.
Fruit juices -- Pasteurization.
Ultraviolet radiation .

Yazar Ek Girişi
Ünlütürk, Sevcan,

Tüzel Kişi Ek Girişi
İzmir Institute of Technology. Food Engineering.

Tek Biçim Eser Adı
Thesis (Doctoral)--İzmir Institute of Technology: Food Engineering.
İzmir Institute of Technology: Food Engineering--Thesis (Doctoral).

Elektronik Erişim
Access to Electronic Versiyon.

KütüphaneMateryal TürüDemirbaş NumarasıYer NumarasıDurumu/İade Tarihi
IYTETezT001994TP440 .A31 2019Tez Koleksiyonu