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UV‐C Irradiation of Freshly Squeezed Grape Juice and Modeling Inactivation Kinetics
Author(s) -
Unluturk Sevcan,
Atilgan Mehmet R.
Publication year - 2014
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/jfpe.12099
Subject(s) - kinetics , chemistry , log reduction , food science , irradiation , lactic acid , bacteria , nuclear chemistry , biology , physics , quantum mechanics , nuclear physics , genetics
UV 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 116.7 J/mL, at three different flow rates (0.90, 1.75 and 3.70 mL/s), were modeled by using log‐linear, W eibull, H om and modified C hick– W atson models. FSTGJ was circulated five times in the UV system, i.e., UV exposure time was 20.33 min during processing. The populations of E scherichia coli K ‐12, lactic acid bacteria ( LAB ) and foodborne yeasts were reduced by 3.759, 4.133 and 1.604 log cfu/mL, respectively, after exposure to UV dosage of 116.7 J/mL at the lowest flow rate. The inactivation kinetics of foodborne yeasts were best described by the modified C hick– W atson model, with the least root mean squared error ( RMSE = 0.001, R 2 = 0.999). Besides, the inactivation kinetics of E . coli K ‐12 and LAB were best fitted by W eibull model ( R 2 = 0.999). Additionally, when the UV exposure time was increased up to 32.5 min (i.e., eight cycles), UV‐C treatment of FSTGJ resulted in 5.341 log cfu/mL reduction in E . coli K ‐12, which meets the Food and Drug Administration requirement of a 5 log 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, W eibull, H om and modified C hick– W atson) are applied to describe the inactivation kinetics of E scherichia 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.