How are bottled sakes generally pasteurised?

Bottled sakes are generally pasteurized by immersing them in hot water or using a hot water shower. This method effectively eliminates any potential spoilage microorganisms and stabilizes the sake without significantly altering its flavor profile. Pasteurization is a critical step in ensuring the product's safety and extending its shelf life.

While other methods mentioned in the choices may be used in other contexts, they do not apply to the standard procedure for pasteurizing bottled sake. Fermentation in a controlled environment is focused on producing sake rather than preserving it post-production. Freezing at sub-zero temperatures is not a recognized method for pasteurizing sake and could lead to undesirable changes in the product. Adding preservatives might prolong the shelf life of beverages but does not replace the need for pasteurization in the traditional sake-making process.