Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
Browse
3 results
Search Results
Article Citation - WoS: 81Citation - Scopus: 115Effects of Ultraviolet Light Emitting Diodes (leds) on Microbial and Enzyme Inactivation of Apple Juice(Elsevier Ltd., 2017) Pelvan Akgün, Merve; Ünlütürk, Sevcan; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, the effects of Ultraviolet light-emitting diodes (UV-LEDs) on the inactivation of E. coli K12 (ATCC 25253), an indicator organism of E. coli O157:H7, and polyphneoloxidase (PPO) in cloudy apple juice (CAJ) were investigated. The clear (AJ) and cloudy apple juice were exposed to UV rays for 40 min by using a UV device composed of four UV-LEDs with peak emissions at 254 and 280 nm and coupled emissions as follows: 254/365, 254/405, 280/365, 280/405 and 254/280/365/405 nm. UV-LEDs at 254 nm achieved 1.6 ± 0.1 log10 CFU/mL inactivation of E. coli K12 at UV dose of 707.2 mJ/cm2. The highest inactivation of E. coli K12 (2.0 ± 0.1 log10 CFU/mL and 2.0 ± 0.4 log10 CFU/mL) was achieved when the cloudy apple juice was treated with both 280 nm and 280/365 nm UV-LEDs. For clear apple juice the highest inactivation 4.4 log10 CFU/mL obtained for E. coli K12 was achieved using 4 lamps emitting light at 280 nm for 40 min exposure time. For the same treatment time, the experiments using a combination of lamps emitting light at 280 and 365 nm (2lamp/2lamp) were resulted in 3.9 ± 0.2 log10 CFU/mL reductions. UV-A and UV-C rays in combination showed a better inactivation effect on PPO than UV-C rays used separately. Residual activity of PPO in CAJ was reduced to 32.58% when treated with UV-LED in combination of UV-C (280 nm) and UV-A (365 nm) rays. Additionally, the total color change (ΔE) of CAJ subjected to combined UV-LED irradiation at 280/365 nm was the lowest compared to other studied processing conditions. This study provides key implications for the future application of UV-LEDs to fruit juice pasteurization.Article Citation - WoS: 22Citation - Scopus: 33Uv-C Irradiation of Freshly Squeezed Grape Juice and Modeling Inactivation Kinetics(John Wiley and Sons Inc., 2014) Ünlütürk, Sevcan; Atılgan, Mehmet Reşat; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyUV inactivation kinetics of freshly squeezed turbid white grape juice (FSTGJ) treated with an annular flow UV reactor by applying UV dosages ranging from 0 to 116.7J/mL, at three different flow rates (0.90, 1.75 and 3.70mL/s), were modeled by using log-linear, Weibull, Hom and modified Chick-Watson models. FSTGJ was circulated five times in the UV system, i.e., UV exposure time was 20.33min during processing. The populations of Escherichia coli K-12, lactic acid bacteria (LAB) and foodborne yeasts were reduced by 3.759, 4.133 and 1.604log cfu/mL, respectively, after exposure to UV dosage of 116.7J/mL at the lowest flow rate. The inactivation kinetics of foodborne yeasts were best described by the modified Chick-Watson model, with the least root mean squared error (RMSE=0.001, R2=0.999). Besides, the inactivation kinetics of E.coli K-12 and LAB were best fitted by Weibull model (R2=0.999). Additionally, when the UV exposure time was increased up to 32.5min (i.e., eight cycles), UV-C treatment of FSTGJ resulted in 5.341log cfu/mL reduction in E.coli K-12, which meets the Food and Drug Administration requirement of a 5log reduction of microorganisms in fruit juices. Practical Applications Consumer demand for high-quality fruit juice with fresh-like characteristics has markedly expanded in recent years. UV-C irradiation is a nonthermal method and allows the processing of fruit juices with a minimal or no changes in flavor, essential nutrients and vitamins. Although thermal pasteurization is the most convenient way of increasing the shelf life of fruit juices, it causes a "cook taste" in grape juice. So, in this study, the application of UV-C irradiation to process grape juice was investigated. The shape of the microbial inactivation curve is sigmoidal in UV treatment. Therefore, different kinetic models (e.g., log-linear, Weibull, Hom and modified Chick-Watson) are applied to describe the inactivation kinetics of Escherichia coli K-12, lactic acid bacteria and foodborne yeasts. Kinetic parameters (e.g., k and D) and models can be used for the development of UV-C irradiation process to ensure microbial safety in juice products.Article Citation - WoS: 124Citation - Scopus: 144Use of Uv-C Radiation as a Non-Thermal Process for Liquid Egg Products (lep)(Elsevier Ltd., 2008) Ünlütürk, Sevcan; Atılgan, Mehmet Reşat; Baysal, Ayşe Handan; Tarı, Canan; Ünlütürk, Sevcan; Tarı, Canan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe efficacy of short wave ultraviolet light (UV-C) as a non-thermal process for liquid egg products (LEP) was investigated. Non-pathogenic Escherichia coli strain (ATCC 8739), which shows lower sensitivity to UV-C light than E. coli O157:H7 and Salmonella typhimurium, was chosen as a target microorganism. The inactivation of UV resistant strain of E. coli in LEP was examined by evaluating the effects of depth of liquid food medium (0.5, 0.3 and 0.153 cm), UV light intensity (1.314, 0.709 and 0.383 mW/cm2) and exposure time (0, 5, 10, and 20 min) by using a collimated beam apparatus. The best reduction (>2-log) was achieved in liquid egg white (LEW) when the fluid depth and UV intensity were 0.153 cm and 1.314 mW/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) at the same conditions. The kinetics of UV inactivation of E. coli in LEP was 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 LEP.