BREWING SAKE IN WINTER - Is It Cold Where You Are Right Now?
It is a plain fact; historically sake brewing took place in the winter only. Of course today they brew year-round with all sorts of new fangled refrigeration and cooler systems, but back in the day Old Man Winter made sake his way and his way only. Why? Several reasons really, and they all came from trial and error. Sake is a fermented beverage, and the act of fermentation requires great energy to convert a starch into a sugar and a sugar into alcohol. This energy is released in the form of heat. And as sake uses yeast to do a lot of this work yeasts are susceptible to death by overheating. Kill the yeasts and the fermentation never gets completed. Thus, how does one keep these yeast cool? You guessed it!
Temperature control is one of the most time consuming and potentially costly mistakes that brewers can make. The temperature must be monitored 24x7 to ensure proper brewing. Each part of the brewing process from steaming the rice to spreading the koji mold onto the rice to the actual fermentation in the tanks is solely dependant on temperature. Therefore brewers could do battle with the increases in heat the natural way by opening the windows to let in the cool winter air. Vents work wonders when the thermometer begins to rise in a fermenting tank of sake.
There is a secondary reason for brewing in winter as well. When the air is cold this lessens the amount of natural airborne yeasts that play havoc with a sake brew in process. One of the most important aspects of a brewery is to keep unwanted yeasts out of the procedure. Thus a cleaner and of course a colder environment helps to aid this process. And lastly, it just looks so much cooler when there is a feint glow of a tank room fermenting along from a snowy far away outside view. Snow and sake go hand in hand like ummmm chicken and sake!