A sample of E. coli has been subjected to heat for a specified time, and 90% of the cells have been destroyed. Which of the following terms best describes this event?
a. Thermal death point
b. Thermal death time
c. Decimal reduction time
d. None of the above

Verified step by step guidance

1. Step 1: Understand the definitions of the terms given in the options. Thermal death point (TDP) is the lowest temperature at which all microorganisms in a liquid culture are killed in 10 minutes.
2. Step 2: Thermal death time (TDT) refers to the minimum time required to kill all microorganisms in a liquid culture at a specific temperature.
3. Step 3: Decimal reduction time (D-value) is the time required at a certain temperature to reduce the microbial population by 90%, which means killing 90% of the cells.
4. Step 4: Since the problem states that 90% of the E. coli cells have been destroyed after heat treatment, this corresponds to the definition of decimal reduction time.
5. Step 5: Therefore, the term that best describes the event where 90% of cells are destroyed is the decimal reduction time.

Key Concepts

Thermal Death Point (TDP)

Thermal death point is the lowest temperature at which all microorganisms in a liquid culture are killed in 10 minutes. It indicates a specific temperature threshold for complete microbial destruction but does not specify the time required at other temperatures.

Thermal Death Time (TDT)

Thermal death time is the minimum time required to kill all microorganisms in a sample at a given temperature. It focuses on the duration needed for complete sterilization at a constant temperature.

Decimal Reduction Time (D-value)

Decimal reduction time is the time required at a certain temperature to reduce the microbial population by 90%, or one log cycle. It measures the rate of microbial death and is directly related to the question describing 90% cell destruction.