Final answer:
The statement is false; the thermal death time refers to the time needed to kill all microorganisms in a sample at a given temperature, not just 90%.
Step-by-step explanation:
The statement that the length of time required to kill 90% of bacteria at a given temperature in a hot-air oven is the thermal death time is false. Instead, the thermal death time (TDT) refers to the duration necessary to kill all microorganisms in a sample at a specific temperature. Understanding the thermal death time is crucial for ensuring that sterilization and disinfection protocols are effective, especially when using dry-heat sterilization methods such as hot-air ovens. These methods are used not only in food preservation but also in laboratory and medical settings to maintain aseptic conditions.
Conversely, the thermal death point (TDP) is the lowest temperature at which all microbes are killed in a 10-minute exposure. Methods like pasteurization utilize moist heat to kill pathogens in food, and high-pressure processing can eliminate microbes without extreme heat. Additionally, some bacterial spores, such as those from C. botulinum, require even higher temperatures for eradication, achievable only through pressure canning. This highlights the significance of selecting an adequate sterilization method based on the specific microbial characteristics of the sample being treated.