The term describing the time to kill all microbes in a sample at a certain temperature is 'thermal death time,' while 'D-value' is the time to reduce the population by 90%.
The term used to describe the time required to kill all of the microbes within a sample at a given temperature is known as the thermal death time. D-value, or decimal reduction time, refers to the time it takes to kill 90% of the population (a 1-log decrease in the total population) when exposed to a specific microbial control protocol. Substantial factors that can impact the effectiveness of a disinfecting agent include the concentration of the agent, the presence of organic material, and the life stage of the microbes (e.g., endospores of bacteria).