Sake ABC Foundations - B3. How Sake is Made
Understanding How Sake is Crafted, from Rice to Bottle
Now that you know how to read a label (seimaibuai, junmai or not, SMV, nama), you understand what describes the finished sake. This module explains how sake is made and covers a few more label terms that B2 missed. The ingredients are the same as always: rice, water, koji, and yeast, with the option to add a legally capped amount of brewer’s alcohol to lift aromas. What makes sake unique isn’t just the ingredients, but what happens during the process.
The Simple Three-Step Overview
Step 1: Prepare the rice. Sake rice is polished and then left to rest for a few days before it is washed, soaked, and steamed. Unlike regular eating rice, it is not cooked. Steaming keeps the outside of each grain firm and the inside soft, which is perfect for the next steps.
The soaking time is controlled very precisely, sometimes down to the second, because the rice absorbs water quickly after the outer layers are removed. If the timing is off, the rice will steam unevenly, which can affect this step and the steps that follow.
Step 2: Grow koji on the rice. Once the steamed rice has cooled a little, it is moved to a warm, humid room. Here, Koji 麹, Aspergillus oryzae, a type of mould, is added to the grains for about two days. Koji breaks down the rice’s starch into sugars that yeast can use. Without koji, the yeast would have nothing to feed on. This step is what makes sake possible. We will cover it in more detail in A3. Koji, but for now, just remember that koji is the driving force.
Step 3: Ferment. Koji rice, more steamed rice, water, and yeast are all added to the tank, but not at the same time. They are added in three increasing rounds over about four days. This gradual process helps the yeast stay strong enough to keep turning sugar into alcohol. A typical batch finishes in two to three weeks. Slower and colder styles, like ginjo, can take a month or longer. Once fermentation is finished, the sake is pressed and filtered.
If filtering uses a coarser mesh and lets some lees remain in the sake, or if some lees are added back after pressing, the sake becomes cloudy. This style is called nigori in Japanese.
Most sake is pasteurised, meaning it undergoes a quick heat treatment to stop enzyme activity. This is done once before the sake rests in a tank to age, and again just before bottling. These two rounds of pasteurisation make the sake shelf-stable. If you skip the first pasteurisation, you get namazume 生詰酒. If you skip the second, it is called namachozo 生貯蔵酒. If you skip both, it is just called namazake. All three types need to be refrigerated.
Why Sake is Unusual
In wine, the sugar is already present in the grapes, so yeast simply ferments it. In beer, malted barley first turns starch into sugar, and then yeast ferments the sugar in a separate step. Sake is different because both steps occur simultaneously in the same tank: koji converts starch into sugar while yeast consumes it.
This is called multiple parallel fermentation. Sake runs them together, a trick it shares mainly with East Asian relatives like huangjiu 黄酒 and makgeolli 막걸리, often overshadowed by the simpler wine-and-beer comparison. That simultaneity is what gives brewers control over flavour and alcohol development, clearly distinct from other brewed products.
What This Means in Your Glass
The slow, cold fermentation is what gives Ginjo sake its floral and fruity aromas, like apple, pear, and melon, as mentioned in B1. These are not added flavours or ingredients. They are a natural result of the brewing conditions. The brewer adjusts the temperature, the amount of koji, and the type of yeast to shape the final taste.
Try this. Next time you open a bottle of ginjo, notice the floral notes. Those aromas are not added. They come from weeks of slow, careful fermentation and show up right where you taste them. If you see a slightly cloudy sake, that’s nigori. It can range from lightly cloudy to thick and fully opaque, and sometimes has a hint of lactic or yoghurt-like notes.
When you get to Part A, the whole process will become even clearer. For now, remember this: making sake is technically complex, so even a simple bottle takes real skill and time to produce.
