As a sommelier and brewer, I can confidently say that soju does not technically expire after opening. However, there are a few factors to consider when assessing the quality and taste of an opened bottle of soju.
Commercially produced soju often contains preservatives that extend its shelf life. These preservatives help prevent bacterial growth and oxidation, allowing the soju to last longer without spoiling. Therefore, if you have a bottle of store-bought soju, it is likely to remain safe to drink for an extended period.
That being said, the flavor of soju may deteriorate over time, even with the presence of preservatives. The delicate flavors and aromas that make soju enjoyable can fade with prolonged exposure to air. This is especially true if the bottle is not properly sealed after opening. So, while the soju may still be safe to consume, the taste may not be as pleasant as when it was first opened.
On the other hand, traditional distilled soju, which is essentially a combination of alcohol and water, will not go bad due to its high alcohol content. This style of soju has been produced for centuries, using simple distillation methods that result in a pure and stable spirit. As long as it is stored properly in a sealed container, traditional soju should not spoil or become undrinkable.
To determine if your opened bottle of soju is still good to drink, trust your senses. If the flavor seems off, the aroma is unpleasant, or there are any signs of spoilage, it is best to err on the side of caution and discard it. While soju may not pose a health risk after opening, consuming a subpar or spoiled soju may not provide the enjoyable experience you desire.
In my personal experience, I have come across opened bottles of soju that have been stored for a significant period. While they were technically safe to consume, the taste had noticeably deteriorated. The vibrant and nuanced flavors that initially attracted me to soju had faded, leaving a lackluster and uninspiring drink. It was a reminder that even with preservatives, the quality of the soju can decline over time.
Commercially produced soju with preservatives can last longer without spoiling, but the flavor may fade over time. Traditional distilled soju, on the other hand, will not go bad due to its alcohol and water composition. Trust your senses when assessing the quality of an opened bottle of soju, and if it no longer tastes enjoyable, it may be time to bid it farewell.