Brewing sake takes a level of dedication that makes all grain brewing seem like child's play. It isn't that the process is hard, it is the time you need to devote to it. For traditional sake, you need to set aside two weeks with additions going into the mass twice a day. It is a process you have to be dedicated to accomplish. But then doing anything well requires dedication.
Despite the common misnomer sake is not a form of wine. It is a beer. Wine is made from fruit; beer is made from grain. In the case of sake, the grain is traditionally rice. For the highest level of traditional sake you need special brewer's polished rice that has been milled about 55%. Typical rice you find at the supermarket has been milled to 95% (this figure refers to how much of the grain is left after milling). The sake rice has had most of its starch and protein polished away to provide a clean finished product. The rice used does play a pivotal role in the finished product.
Rice does not bring enzymes to convert the starch like you find with barley. Instead the brewer needs to create an enzymatic starter mash called a Kome Koji (also known as Koji rice). Essentially starter rice is inoculated with koji spores. To this starter sake yeast is added. From that point additions are made twice a day to feed the yeast and koji. With this the brewer is building the fermentation so that in its final addition the finished sake will finish around 15% alcohol.
This description is very generalized. You can find a fully detailed description of the process at Homebrew Sake. This is the process I will be following for the next few weeks for this project. The one exception I will be making is I will be using a medium grain rice instead of sake rice (sadly I couldn't find sake rice when I was picking up ingredients). As luck would have it, there are instructions for dealing with "dinner rice" in the directions found on the site.
An interesting note: this is still sour beer month, so how does sake fit in? I am glad you asked. The methods used to prepare the koji and the rice additions allow for wild bacteria to enter the mash, especially lactobacillus. Traditionally sake is pasteurized to kill off the wild yeasts when it is finished. Because of space issues I will not be going to that extreme. But I will be using sulfites as is common for vintners to stop fermentation before bottling.
So there are a couple spots that are breaking from tradition. The nice thing is, this is for my own enjoyment so I can break tradition if I want to. When you are in your own kitchen or your own brewery, you get to make the rules.
Time for a pint...