Viamver® yeast is a “house” yeast found in the miso of Yamamo Miso and Soy Sauce Brewing Company. The genus of the yeast is Zygosaccharomyces rouxii (hereafter referred to as Z. rouxii). It is one of the most typical salt-tolerant yeasts in the fermentation of miso and soy sauce.
So what is so special about Viamver® yeast? Normally, when we talk about "salt-tolerant yeast" we are talking about yeast that can operate in the presence of salt. You might think of yeast that promotes alcoholic fermentation in wine or liquor without salt, but there are also yeast strains, like Z. rouxii, that are more active in miso and soy sauce that use salt.
This means that this strain is not suitable for brewing alcohol. It’s even considered a spoilage fungus in wine making.
However, Viamver® yeast is different: it is Z. rouxii, and yet it is able to continue fermentation without weakening at all, even under unsalted conditions. Why was such a yeast found in Yamamo's miso in the first place?
It was a discovery that came about after Yasushi Takahashi, the seventh generation, took over the company and started to use microbes used in industries outside the miso and soy sauce industry. He applied technologies from other industries and conducted unusual experiments that did not follow conventional theories.
In the tenth year of this irregular research, the yeast was discovered in his experimental miso. This was a microbe that he would never have encountered in the same method of miso production. On the top of it, even if a microbe is a new species or has a new efficacy, it wouldn’t have been possible to use if it kills other useful microbes. This means that the chance of finding useful microbes is very low and difficult.
In fact, in the second year of his experiment, Takahashi was already able to produce 6% alcohol from miso (normally less than 3%). This inspired him to see the potential of this yeast for more than just miso and soy sauce, so he asked experts in alcoholic beverages and lactic acid bacteria to analyse it. He has taken a rather unique approach and conducted multifaceted tests, such as trying salt-free conditions and using fruits, nuts, and mushrooms unrelated to miso and soy sauce as ingredients.
As I mentioned in my last post, this was a rather outlandish idea in the miso and soy sauce industry, where people expect miso to "stay the same";. Takahashi didn’t care. He thought that this yeast should be used not only for miso and soy sauce, but also for fermentation and brewing of sake and wine across the board.
He set up a research team called ASTRONOMICA® to explore fermentation that makes the most of this yeast. (Read more at https://bit.ly/3qqgNjL)
As the research progressed, it was discovered that this yeast could produce succinic acid, a flavour component obtained from fish and shellfish, twice as much as normal Z. rouxii. In addition, it has the ability to ferment without salt and to produce around 6% of alcohol.
Moreover, it also has a gorgeous aroma similar to that of fruit or ginjo, ability to improve the quality of the flesh, and even has a masking effect.
"I can't waste the potential of such a multi-talented yeast like this." Takahashi applied for a microbial patent for the yeast and a production process patent for high succinic acid. Then he went on to present his findings at Brewing society of Japan and applied for international trademarks.
I can tell you that this is an extremely rare story of a small brewery from a rural area that went this far.
All these decisions were made based on his clear vision to preserve the techniques and discoveries in an objective manner, while bringing innovation to the industry as well as introducing the new value of fermentation to the world from Japan.
Takahashi named this yeast strain Viamver®, and applied for international trademark registration on ASTRONOMICA® too.
Since then, ASTRONOMICA® has been experimenting not only to make innovative miso and soy sauce, but also to brew natural wine that uses this gorgeous aroma and flavour of this yeast.
What’s next? Takahashi wants to use this yeast in doburoku and beer even, so more interesting parings can be achieved in the future. No one can stop him now.
At MONO MONTHLY YAMAMO, we share this chance to try the ASTRONOMICA® labelled soy sauce, salt, and hot sauce from their research. How exciting is that What’s the taste like? Well, let’s find that out in the coming posts. Stay tuned.