Have begun my second batch of Genshu sake and am following the same methods used previously this past spring. This summer I successfully made a batch of koji derived from growing and collecting spores from a container of Cold Mt Koji. I plan on using the Cold Mt rice and my own batch of koji in the brewing this time. There is a noticeable difference in taste and smell between the store-bought koji and what I grew and made using it. Cold Mt has a more neutral aroma, leaning towards vanilla, while what I made has a strong uniform nutty aroma and a tangy taste/flavor while Cold Mt is not very aromatic and only slightly sweet.
My question about mixing koji…is using my own going to create a totally different product, or does all the rice dissolve equally and temperature the only major taste/aroma factor?