Thermal Death Time

Thermal Death Time# TDT# Thermal Processing# Food Pocessing Technology# Thermal Death Time Concept # TDT Curve # Unit operations in Food Processing # Food Technology in Industry# Food

1. Food processing Technology Thermal Death Time M. Ragadeepa Assistant Professor Department of Food and DairyTechnology Mannar Thirumalai Naicker College

2. Content Introduction Definition TDT curve End point curve What's an example of thermal death time? Conclusion

3. Introduction : It is defined as number of minutes of heating required to destroy a specified number of organisms at a given temperature. The thermal death time follows a logarithimic relationship with the temperature of heating.

4. Definition : This means as we increase or decrease the temperature of heating, the thermal death time for bacteria will increase or decrease in a logarithmic scale.

5. TDT curve : Therefore if we plot the TDT values on a log scale of a semilog paper (The graph paper which has vertical grids on log scale and horizontal grids on linear scale), and the temperature of heating on linear scale, we would get a straight line. When TDT plotted on the log scale and temperature of heating on linear scale, a straight line of best fit is known as thermal destruction curve or thermal death time (TDT) curve.

6. End point curve : 15 The TDT curve constructed in this manner is called end point curve. This curve can be used for finding out the thermal death time for a fixed number of organisms at an unknown temperature. TDT values obtained in this manner are valid only for the number and type of organisms used in that particular experiment.

7. What is an example of thermal death time? The thermal death time of microorganisms can vary, depending on the thermal tolerance of the microbes. For example, thermophilic bacteria such as Thermophilus aquaticus that can tolerate high temperatures will have a thermal death time that is longer than the more heat-sensitive bacterium Escherichia coli.

8. Conclusion : Thermal death time is how long it takes to kill a specific bacterium at a specific temperature. It was originally developed for food canning and has found applications in cosmetics, producing salmonella-free feeds for animals (e.g. poultry) and pharmaceuticals.