As you may know, sake is also called 'rice wine'. Do you know what is the difference between sake and wine besides the material? The topic is chemical but let me explain clearly. You must have heard the word fermentation. You can easily find fermented products in your daily life, such as cheese, bread, yogurt, etc. Fermentation occurs when microorganisms (yeast, bacteria) decompose organic matter and convert it into a specific substance. Yogurt and cheese are made from fermented milk for example. To make alcohol, one kind of fermentation needs to occur - called alcoholic fermentation. Here, microorganisms are yeast, organic matter is sugar and the specific substances are alcohol and carbon dioxide. Wine is made from grapes and grapes contain lots of sugar. So the alcoholic fermentation naturally happens when yeast is added to them. The yeast converts the grape sugar into alcohol and carbon dioxide. Sake, on the other hand, is made from rice. Is rice as sweet as grapes? No. First rice needs to become 'sweet' and then it can be converted into alcohol and carbon dioxide. How? There is a magician who can create sugar from rice - it's called Komekoji, meaning rice mold. Rice contains starch and komekoji converts it into sugar (glucose). Have you ever eaten sticky rice? If so, you may have noticed that there is a slight sweetness when you keep chewing it. This is because saliva contains amylase which works in a similar way as komekoji, converting starch into sugar. After that, the yeast can finally start the alcoholic fermentation. While for wine the alcoholic fermentation is called single fermentation, the one for sake is called multiple parallel fermentation. This extra process makes sake a bit more expensive than wine in general because sake brewers need to be really careful to make this fermentation occur perfectly.