So this is how the White Koji works. Most Sours are produced using a bacteria that produces lactic acid. White Koji is just is one of several species of the filamentous fungus genus Aspergillus. White Koji (Aspergillus kawachii) is used for the purpose of converting the starch in grains into sugars fermentable by yeast. In the conversion process involving white koji, ample amounts of citric acid are produced which lowers pH and yields a delicately sour citrusy flavor.
The white koji fungus, Aspergillus luchuensis mut. kawachii, is used for the production of shochu, a Japanese traditional distilled spirit. It produces large amounts of amylolytic enzymes and citric acid during the fermentation process. There are three types " black Koji" “white Koji” and “yellow Koji”. The Black Koji is mainly used for fermentation of Awamori. White Koji is for Shōchū and Yellow Koji is for sake.
Very interesting. I’ve only used the Sake species. I know the distillery behind my shop was making a Korean version and the master brewer was trying to explain to me the differences between different Asian varieties. At the time it was over my head.
There are some restaurants using koji to age and tenderize their meats. That is supposedly amazing as well. I’d love to make some miso and soy sauce but I have a few too many fermentation projects going on right now.
I guess the black koji makes a lot of citric acid as well.
@damian_winter where did you get your white koji?
I got mine from one of the Oriental store down the road from me. I done a lot of research on it because even though some brands say White Koji doesn’t mean that the spore on the rice are still alive. During my research i learned about the production of it on rice and even malted grain… Very similar to how Sour or Acid Malt is created rice or grain is rinsed with warm water to kill any unwanted bacteria and bugs. Then is allowed to cool the spray a mist of the spore over the Rice or grain. In Sour malt the a mist of lactic acid or bacteria over the grain. There is also some unique advantages to using it also to sour with because it produces citric acid there is less of a chance for undesirable contamination from bacteria.
I’ve not used black for anything yet. Due to it producing black pigment that will stain your equipment. But i plan too later on. Maybe with some unique Stouts. I plan on doing some futher research and will keep updates along the way for everyone
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Update on brewing Beer with Koji ( Aspergillus Oryzae). I have been furthering my research of brewing beer with Koji spores and really creating some very unique beers and flavors. I mainly been working with White Koji. So one of my recent experiments of brewing with it is a Belgian White recipe. 50% Pale malt 50% White Wheat. I decided to use the kettle souring technique and introduce the spores into the Wort. I did do a 20 minute boil just to knock out any unwanted yeast or bacteria. Cooled wort down to 86 degrees. Which seems to be the sweet spot for the growth of the spores and citric acid production. Now this is where it gets interesting. I kettle soured it for 24 hours before returning it to boil and adding my Hops, Coriander and Orange peel. But back to the kettle souring. The Koji spore also created Protease and Amylase enzymes during the kettle souring process.
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