Does koji go off?

[jonathansw9]

I've been making Amazake using the 'keep warm' setting on my slow cooker for a few months. All was fine initially but recently I have felt drained of energy shortly after eating it. I just cannot figure out why.
I bought three bags of Koji from a shop in London some time ago. Initially I just stored them in the cupboard but now keep them in the fridge. Does anyone know if the koji may have gone off? The 'use by date' is still some way off however and the Amazake tastes fine. It's very puzzling. I had so much energy when I first started making it which came as a relief after years of struggling with normal porridge.
I want to feel alive again! Please help!

[Tim Hall]

Dried koji or fresh? I'm sure fresh koji will go off very quickly as it's a perfect medium for growing bacteria and yeasts. Dried koji I would think should last quite a while...assuming it wasn't kept under poor conditions, possibly losing enzyme activity.