By Will Jarvis, Sake Matters

GETTING STARTED: Kimoto & Yamahai Series

Summer is well and truly here. Shaking off some of the restrictions is allowing a bon viveur mentality to take hold. Consumers are flocking to patronise again old haunts and slowly help them recoup the lost fortunes of the last eighteen or so months.

Brewers too across North America have reconnected with the passionate experimentation that got sent reluctantly into hibernation during the darker months of the pandemic, with the traditional yeast starters (“motos” or “shubos” in Japanese, the terms are interchangeable) known as yamahai shikomi and kimoto-tsukuri playing a big part.

As both yamahai and kimoto are processes that can be applied to all grades of sake, they’re definitely going to be on your radar at some time or other, so knowing what you’re ordering is important. Time for a fast-track to moto appreciation:

  • Yamahai and kimoto sakes are largely similar to each other in that their yeasts are left to multiply in a rich lactic acid soup created by harnessing the bacteria naturally
  • Yamahai and kimoto yeast starters take four, not two, weeks like their modern counterparts to reach a state of readiness
  • This extended period allows wild microbes to briefly add their gamey (“rambunctious” John Gaunter calls it) contribution to the end sake

Basically “Wild” Mother Nature takes her time, but it’s up to you how you want to remember it.

So what’s really going on in tank? Well, like all alcoholic fermentations, sake needs yeast cells, lots of them. We’re talking tens of millions of cells in just a few drops of liquid. To provide the ideal environment for sake yeasts to thrive, all else needs to be wiped out.

Only lactic acid can do this without obliterating everything inside, the unwanted and the wanted. Through some wonderful coincidence lactic acid and the yeast can coexist where nothing else can, but the key point here is how the lactic acid is introduced.

These days and since 1911 actually, in really the vast majority of cases, lactic acid is added by brewers from a cultivated pure vial, unleashing the selective death and destruction required quickly and effectively. Today’s sokujo moto (“fast” moto) dominates the market and uses this shortcut, but yamahai and kimoto do not.

Before 1911, there was no other way. Lactic acid had to be cajoled and introduced naturally into the moto. There was no work around. This process takes time but at the end of the four weeks the yamahai and kimoto yeast starter is largely, on the surface at least, in the same ballpark as sokujo moto.

That is, except for a critical factor that explains the aromatic and flavor differences within the resulting kimoto and yamahai sakes. During their four-week period of moto development, the foundations for yamahai and kimoto sakes are essentially a playground for all kinds of wild entities to have their moment in influencing the end sake. It’s like Spring Break in there!

As to exactly when the lactic acid bacteria gain supremacy will vary each time but either way, foreign microbes have had a window to make their mark and forever be part of the final beverage. This all leads, usually, to a richer, wilder flavor for sakes fermented from a yamahai and kimoto yeast starter compared to the cleaner flavor profiles of sokujo moto.

But what of the differences between yamahai and kimoto? The next article will take a closer look at the original yeast starter, kimoto, which was until 1909 or so the only option out there for brewers for centuries. Now making a comeback, we’ll see just what this slice of sake history means to brewers in North America.

The opinions expressed in this article are those of the author and do not necessarily represent those of the Sake Brewers Association of North America or its members.

A certified sake sommelier, Will Jarvis is the owner and founder of Sake Matters, consulting for a variety of clients in Hong Kong and around the world. He has over 20 years’ experience working in the F&B industry in Europe, the Middle East and Asia, is a trained chef and holds a diploma in hospitality.