Uridine as a non-toxic actinometer for UV-C treatment: influence of temperature and concentration
Jaayke L. Fiege,
Benedikt Hirt,
Volker Gräf,
Stefan Nöbel,
Dierk Martin,
Jan Fritsche,
Katrin Schrader,
Mario Stahl
Affiliations
Jaayke L. Fiege
Department of Food Technology and Bioprocess Engineering, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-76131 Karlsruhe, Germany; Corresponding author.
Benedikt Hirt
Department of Food Technology and Bioprocess Engineering, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-76131 Karlsruhe, Germany
Volker Gräf
Department of Food Technology and Bioprocess Engineering, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-76131 Karlsruhe, Germany
Stefan Nöbel
Department of Safety and Quality of Milk and Fish Products, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-24103 Kiel, Germany
Dierk Martin
Department of Safety and Quality of Milk and Fish Products, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-24103 Kiel, Germany
Jan Fritsche
Department of Safety and Quality of Milk and Fish Products, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-24103 Kiel, Germany
Katrin Schrader
Department of Safety and Quality of Milk and Fish Products, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-24103 Kiel, Germany
Mario Stahl
Department of Food Technology and Bioprocess Engineering, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, D-76131 Karlsruhe, Germany
UV-C treatment is an effective method to inactivate microorganisms and therefore gets increasingly more attention in food industry, especially for liquid products. To test and monitor different UV-C reactor designs, a photochemical actinometer is required that gives reliable UV-C dose values and is non-toxic allowing frequent control of the production chain. Here, a variable concentrated aqueous uridine solution is tested as a photochemical actinometer. Uridine reacts at 262 nm by photohydration to a single photoproduct not absorbing any light. A concentration dependent quantum yield (Ф) was quantified in the range of 0.2–3.0 mM uridine. Results show that uridine is as accurate as the commonly accepted iodide/iodate actinometry, but not as precise. Especially at higher concentrations a higher number of measurements becomes necessary. Further, a temperature correction is presented for 10 °C > ϑ > 30 °C. Taking these results into account, uridine can certainly be considered as a non-toxic dosimeter for UV-C systems.
