To keep it from spoiling, producers pasteurize it and also remove all the oxygen in a process called deaeration.
为了防止它们损坏，制作中会用巴氏法灭菌以及有一个排气的过程来排出所有的氧气。
英语百科
Deaeration
Deaeration is the removal of air molecules (usually meaning oxygen) from another gas or liquid. It can refer to:
Deaeration is used in the upstream oil & gas industry to remove oxygen from seawater, preventing or reducing corrosion, and growth of bacteria.
It is also used in the process inks and coatings industry to prevent foaming during production and get a higher quality print or coating layer without air bubble defects.