What does it mean to sterilise food?

Sterilising food refers to the process of eliminating all microorganisms, including bacteria, viruses, and fungi, that can cause spoilage or foodborne illness. The correct answer involves heating food in sealed containers to a temperature of 100 degrees Celsius for 30 seconds. This method is effective because high temperatures can kill most pathogenic organisms and spores, ensuring that the food is safe to consume and can be stored for longer periods without the risk of contamination.

This sterilisation process is particularly important for canned and preserved foods, where maintaining a stable, safe environment is crucial for shelf life. It creates a vacuum seal when the food cools, which further helps in preventing new microbes from entering the containers, thereby maintaining the food's safety and quality over time.

The other answers focus on different preservation methods but do not achieve complete sterilisation. Cooking at high temperatures to enhance flavor may help with taste and safety but does not necessarily sterilise the food. Freezing food preserves it by slowing down enzymatic activity and microbial growth but does not kill all microorganisms. Cooking with steam can enhance food safety by cooking it thoroughly, but it does not guarantee that all microbes are eliminated unless done at the correct high temperatures for a specified time.