Natto has a unique scent, and while some people don't like it, others love it. The scent comes naturally as a fermented foood, and is naturally produced when soybean proteins are broken down. The main components of the scent are pyrazines, short-chain fatty acids, and diacetyl, and the scent gradually becomes stronger as the fermentation progresses.
Recently, with newer fermentation management, natto that has less of the characteristic scent has become available in stores. Whether you like the scenet or not, properly fermented delicious natto is sold refrigerated in Japan. ​

Why natto is good for you?