Once you open a bottle of sake, exposure to air causes the drink to oxidize and lose its flavor quite fast. However, sake’s lifespan can vary depending

on whether it’s pasteurized.

Pasteurized sake can typically last for one to two years when tightly sealed and stored in the fridge, whereas unpasteurized sake lasts for only two to

four weeks once opened.

That is because unpasteurized sake, also known as namazake, retains bacteria and yeast from the brewing process and thus spoils more quickly than its pasteurized counterpart.

In fact, even a never-been-opened bottle of namazake doesn’t last longer than six months. Still, keeping this kind of sake in the fridge can help maximize its shelf life.