Related Experiment Video
Updated: Aug 26, 2026

Isolation and Biophysical Study of Fruit Cuticles
Published on: March 30, 2012
Kinetics of maneb degradation during thermal treatment of tomatoes
Stella Kontou1, Despina Tsipi, Constantina Tzia
1Laboratory of Food Chemistry and Technology, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Polytechnioupoli Zografou, 15780 Athens, Greece.
Abstract:
The kinetics of maneb degradation in tomato homogenates at high temperatures and at two pH values (4 and 9) and the rate of formation of the toxic metabolite, ethylenethiourea (ETU), were studied. Maneb was measured as carbon disulfide by headspace gas-chromatography and ETU by high-performance liquid chromatography with photodiode array detection. First-order kinetics adequately described the degradation of maneb in tomato homogenates. The degradation rate constants exhibited an Arrhenius temperature dependence in the range from 50 to 90 degrees C and the apparent activation energy (E(a)) was calculated to be 36 KJ mol(-1) in homogenates with natural pH (4). Raising temperature from 60 to 75 and to 90 degrees C, ETU formation was significantly increased. Interestingly, the selectivity toward ETU showed a downward trend when the total conversion increased at longer heating times. When the pH of the tomato homogenates was adjusted to 9, the degradation of maneb proceeded faster at both 60 and 90 degrees C. The combination of alkaline pH and the highest temperature (90 degrees C) resulted in the maximum ETU conversion rates. The results of the present study on the fate of maneb and ETU residues during tomato processing, may prove valuable in estimating potential risk from dietary exposure.
More Related Videos
07:40A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes
Published on: October 22, 2016
07:07Controlled-release of Chlorine Dioxide in a Perforated Packaging System to Extend the Storage Life and Improve the Safety of Grape Tomatoes
Published on: April 7, 2017
Related Concept Videos
Physical Methods for Controlling Microbial Growth: Temperature
Principles of Food Preservation
Enzyme Kinetics
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...
Methods of Controlling Food Spoilage
Pasteurization and Food Preservation
Effects of Temperature on Free Energy