Mouldy rice is not usually something to get excited about, but there is one instance in which mouldy rice is actually a good thing: sake, Japan's crowning achievement in the spirits world.
Sake is often mistakenly referred to as “rice wine,” though it isn't really a form of wine at all; though the sake-making process resembles beer production, it's really not a form of beer either. Sake is just its own unique breed of liquor.
The origins of sake are unknown. Though it is referenced several times in Japan's first written text, the Kojiki, which dates back to the eighth century, it's probably safe to say that sake had been around for quite a while before that.
To make sake, you start with a special type of rice, shuzo kotekimai, which is grown specifically for this purpose. The rice must be milled, or polished, which removes the coarse outer layer of the grain and leaves the pearly, starchy interior. The degree of milling determines the final quality of the sake, and the more the better: junmai sake is 30 percent milled—meaning 70 percent of the grain is left—ginjo is 40 percent percent milled, and daiginjo is 50 to 65 percent milled. Look for these terms on the label to give you an indication of the overall quality of that particular bottle.
After milling, the rice is washed, soaked and steamed. The cooked grains are then sprinkled with koji (Aspergillus oryzae), a special type of mould that grows on the rice for a few days until it is fuzzy, grey and really gross looking. The koji secretes an enzyme that converts the rice's starch to sugar, which is necessary for the next step: fermentation. The mouldy grains are mixed with more rice, along with water and yeast, and left to ferment for a couple weeks. Finally, the mash is pressed, filtered, pasteurized, aged and bottled.
You might not think something that comes from mouldy rice could be so diverse, but there is actually a wide range of styles and types of sake. The cheapest stuff, called futsuu, is flat and one-dimensionally boozy—this is the category into which most of the mass-market sake falls. The top-shelf sakes, on the other hand, are just as complex and interesting as a great bottle of wine. Junmai refers to pure rice sake, and the aforementioned milling terms describe how refined the sake will be. (Plain junmai is ok, junmai-ginjo is good, and junmai-daiginjo is really good.)
In terms of flavour, sake is unlike anything else. It has a definite rice-like quality, though it can also have an array of secondary characteristics that range from fruity and floral to earthy and rich. On the palate it is usually dry or slightly off-dry.
The majority of sake is filtered so that it is clear, but nigori sake is unfiltered so it retains a creamy white appearance and feels very round, milky and sweet on the palate. It also settles in the bottle so you need to shake it before serving.
Traditionally, sake is heated and served at body temperature but all of the premium sake producers recommend that you serve their products slightly chilled, like white wine. Sake is usually around 15 to 20 percent alcohol, and heating it up only exacerbates the burn and prevents you from smelling and tasting anything other than the booze. Heating it can also mask some of the faults or deficiencies of low-quality sake, however, so it's not a bad thing to do with the cheap stuff. The easiest way to heat sake is to put the bottle in a pot of water on the stove over medium-low heat—make sure you take the cap off the bottle first.
Sake is traditionally served in small ceramic cups or saucers. This is fine for the ordinary stuff, but if you're investing in a really nice bottle, I recommend serving it in a wine glass—this will allow you to savour the full range of flavours.
It shouldn't be any surprise that sake is fantastic when paired with sushi, or any other seafood/rice-based Japanese dish. In fact, because sake can taste quite strange to neophyte drinkers, it's a good idea to try it the first time with sushi—the food will offset the alcohol content as well as the novel flavours. V