What methods are used to keep astonauts food from spoiling?

There are a number of methods used to keep astronaut food from spoiling. These include:

* Vacuum sealing: Freeze-dried food is vacuum sealed to remove any air, which helps to prevent spoilage.

* Retort processing: This process uses high heat and pressure to kill bacteria and mold, and can be used on both wet and dry foods.

* Chemical preservation: Some foods are preserved using chemicals, such as sodium benzoate or potassium sorbate.

* Low-acid canning: This process is used for foods with a pH of 4.6 or higher, and involves heating the food to a temperature of 250 degrees Fahrenheit for a specified amount of time.

* Freezing: Freezing can be used to preserve food for long periods of time, and is often used for meat, poultry, and fish.

In addition to these methods, astronauts also have access to a variety of fresh fruits and vegetables that are grown on the International Space Station.