PhD on formation of 3-chlorotyrosine by use of hypochlorite in foods

Huynh Nguyen Bao Loan, who is affiliated with Research group Food chemistry and human nutrition (nutriFOODchem), submitted her PhD. The title of the dissertation is 'Formation of 3-chlorotyrosine by use of hypochlorite in foods', promotor is Prof. dr. ir. Bruno De Meulenaer. The public defence will take place on Friday May 19th, 2017.

Abstract of the doctoral research

In the food industry, hypochlorite is used to reduce the microbiological load of foodstuffs. Its use may result in the formation of toxic disinfection byproducts. However it is currently generally accepted that below particular intensities its use does not represent a safety concern even in direct contact with foods. In addition however, the use of hypochlorite in contact with foods should also be considered in the framework of consumer acceptance. The formation of 3-chlorotyrosine seems a potential analytical target to assess the use of hypochlorite in foods.
Firstly, the potency of 3-chlorotyrosine was evaluated as an indicator for the use of hypochlorite in contact with foods in comparison with the other molecular changes in proteins using casein and whey proteins as a model at various oxidant/protein ratios and at different pHs.
Secondly, 3-chlorotyrosine formation was evaluated in four fish species (whiting, European plaice, gilthead seabream and Atlantic salmon) as a result of hypochlorite dipping.
The last set of experiments studied the formation and occurrence of 3-chlorotyrosine in ready-to-eat (RTE) vegetables on the Belgian market. In addition, the dietary exposure via RTE vegetable consumption for Belgian and Spanish populations, exemplifying Northern European lower RTE vegetable consumption and Mediterranean higher consumption patterns, was estimated.
This study has demonstrated, for the first time, that 3-chlorotyrosine is a potential marker to detect the use of hypochlorite disinfectants in fish fillets and vegetables. The levels of 3-chlorotyrosine not only depend on the level of hypochlorite used, but also on the pH, the type of protein and its tyrosine content. This study is the very first to assess the dietary exposure of populations to 3-chlorotyrosine through the consumption of RTE vegetables. Overall, the results indicated that even a small amount of hypochlorite in the washing water can generate relevant concentrations of 3-chlorotyrosine in the treated vegetable. On the basis of this study, concerns with respect to the impact of the use of hypochlorite on chemical food safety are identified.

Brief Curriculum Vitae

Huynh Nguyen Bao Loan was born on October the 30th, 1974 in Cantho, Vietnam. From 10/1997, she worked as a quality control officer at the Physicochemical and Food Testing laboratory, Cantho Center of Technology, Cantho Department of Science and Technology, Vietnam. In 2001 – 2002 she followed a master program in Biotechnology at the Asian Institute of Technology, Thailand, with a scholarship of the government of The Netherlands. From 09/2015 she was the Deputy Director of the Cantho Center of Technology. Since May 2012, she has been working on her PhD project under the guidance of Prof. dr. ir. Bruno De Meulenaer, at the Department of Food Safety and Food Quality (Faculty of Bioscience Engineering, Ghent University). During her PhD, she supervised two students and has published her research in three peer-reviewed scientific journals. Her research project was funded by the Mekong 1000 Project (Vietnam) and the nutriFOODchem unit (Ghent University, Belgium).

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