Sake is very sensitive. Even a few hours of sunlight would rapidly deteriorate the quality of Sake, changing its color. This would also lead Sake give odors.
This deterioration of Sake quality occurs when organic compounds like vitamins in Sake are affected by the ultraviolet rays. On top of that, Sake aromas deteriorate when Sake is exposed to high degree temperature of 30 degrees Celsius or more for a long time.
What colors are Sake bottles in?
To prevent those negative effects, Sake bottles are usually in such dark colors as black, brown and green. Those colors block the ultraviolet rays more than other colors do. Black blocks UV rays the most, followed by brown and green. In recent years, some breweries use Sake bottles in transparent color which still cuts the UV rays.
Sake bottles are in black, brown, green, blue, white or transparent color. The darker the color is, the more it cuts the UV rays.
Pitfall of Storing Sake
You must remember that not only Sunlight but also artificial lights like fluorescent lights deteriorate the quality of Sake. You should store Sake wrapped in newspaper or whatever so that Sake is not exposed to light or heat, no matter what the color of the Sake bottle is.
3 Steps to store unopened Sake bottles
1. Wrap the Sake bottle in newspaper or some paper, or store it in a box.
2. Store it in a closet or somewhere dark, under no sun light or artificial light
3. Store it in a cool place.