Give an example of an application use of thermal death time?

Answer 1

This can be used to determine how long it will take bacteria to die. It was used in cooking to determine how hot the food needed to get in order for customers not to get sick if bacteria were present.

Answer 2

In the food industry, it is important to reduce the amount of microbes in products to ensure proper food safety. This is usually done by thermal processing and finding ways to reduce the number of bacteria in the product. Time-temperature measurements of bacterial reduction is determined by a D-value, meaning how long it would take to reduce the bacterial population by 90% or one log10 at a given temperature. This D-value reference (DR) point is 250 °F (121 °C) or 121 °C.

z or z-value is used to determine the time values with different D-values at different temperatures with its equation shown below:

where T is temperature in °F or °C.

This D-value is affected by pH of the product where low pH has faster D values on various foods. The D-value at an unknown temperature can be calculated knowing the D-value at a given temperature provided the Z-value is known.

The target of reduction in canning is the 12-D reduction of C. botulinum, which means that processing time will reduce the amount of this bacteria by 1012 bacteria per gram or milliliter. The DR for C. botulinum is 0.21 minute (12.6 seconds). A 12-D reduction will take 2.52 minutes (151 seconds).

This is taught in university courses in food science and microbiology and is applicable to cosmetic and pharmaceutical manufacturing.

In 2001, the Purdue University Computer Integrated Food Manufacturing Center and Pilot Plant put Ball's formula online for use.