Wednesday, May 19, 2010

Sake Yeast Starter (Moto)

After producing koji (mold coated enzymatic rice) for my first batch of sake I moved onto the moto (yeast starter).  Unlike beer, where literally hundreds of yeast strains are used, and most well known breweries have at least one proprietary house culture, most sake producers use one of just a handful of yeast strains.  Luckily the most popular is available to homebrewers from Wyeast as 4134 Sake #9.  The strain is known for its light, but complex esters and high alcohol tolerance.

Traditionally high grade sake is made from short grain rice that has been highly polished.  The further a grain of rice is polish down the more of what remains is starch.  Much like wine grapes, there are certain varieties of rice that are highly prized for sake production.  Sadly there isn't any sake polish/variety rice available locally, so I went to the big local Asian grocery store (Great Wall) and picked up a 15 lb bag of Nozomi "Koshihikari" rice, the most expensive sushi rice they had (it was still only $20).  Using less polished rice may mean that my finished sake will have a yellow hue and some extra rice flavor, but it should be fine for a novice sake drinker. 

When brewing sake, just like strong beer, the yeast cell count needs to be brought up before the the main fermentation starts.  Instead of making a starter from malt extract though, koji is mixed with washed/soaked/drained/steamed/cooled rice and water (laced with Epsom salt and yeast nutrient) and allowed to sit for two days while the enzymes start breaking down starches into sugars.  By the time the two days had passed and I was ready to pitch the yeast into the starter it looked like fermentation had already started.  Once the yeast is added to the starter and given time to start fermenting at a cool temperature it needs to be stirred twice a day for three days then once a day for three more days, to distribute the yeast and enzymes. Hopefully the sake strain was able to out-compete whatever other microbe(s) got in there.

The yeast starter or moto for my first batch of sakeAfter the yeast finished fermenting (6 days), I chilled the starter to 50 for five days.  During this low temperature rest lactic acid bacteria (since there are no hops to inhibit them) do what they do best, produce lactic acid.  This adds a hint of tartness that helps to give balance to the finished sake. At this point the starter tasted yeasty, alcoholic, and a bit tangy (which seemed about right to me).  A less traditional method which speeds up production, involves skipping this stage and dosing with lactic acid.

Despite the fact that things are going smoothly, the sake "brewing" process is starting to test my patience a bit; after nearly three weeks of work (soaking, steaming, stirring etc...) I have about a quart of liquid to show for my effort. Luckily now that the yeast is ready I'll be ramping up the batch to four gallons (the full volume) with additions of rice, water, and koji over the next four days.

Next step Moromi

---------------
5/03/10 Mixed 1/2 cup of the koji with 2.5 cups of water (4 g Wyeast nutrient and .7 g epsom salt).  Put into the fridge for an hour while I soaked/drained/steamed 1.5 cups of rice.

Stirred twice a day.

5/05/10 There already appeared to be a small fermentation going after 48 hours. I pitched the smack pack of yeast and put the bucket into the cooler at 50 degrees to ferment.

5/07/10 (36 hours later) moved back to basement

Stirred/swirled twice a day for three days, then once a day for three more days

5/13/10 Moved to fridge @ 50 degrees for a 5 day rest before the main koji/rice additions start.

5/18/10 Ready for Moromi.

4 comments:

Chris said...

As a man that drank more then my share of sake while living in Japan I know there is a big difference between good and great sake. I hope you made great sake because that is a hard thing to do from what I've heard.

Taylor-MadeAK said...

"the sake "brewing" process is starting to test my patience a bit"

This from the guy who leaves beer in a secondary or tertiary fermenter for years at a time? Man, you crack me up!

I'm glad the process is going smoothly for you. You seem like you have a darn good handle on it (I would expect nothing less from the Mad Fermentationist), but let me know if there's anything I can do to help you out. =)

The Mad Fermentationist (Mike) said...

One of the things I love about brewing beer is that it is a one day process (primarily) followed by weeks/months of waiting. With sake it seems like I often have a couple things a day I need to do (last night when I got home from dinner I added koji to my batch, this morning before work I washed and started soaking the rice for my addition tonight, etc...). Instead of being able to block off 6 hours to brew I have to remember all of these small pieces.

Taylor-MadeAK said...

Oh, I know the sake brewing process is more drawn-out and fiddly than brewing beer. I was just having a little laugh at your expense. =)

The whole "having to do something with the sake brewing every day" thing is one reason why I love doing it so much: it gives me something to do during the long, dark Alaskan winter. Yeah, it's tedious...but even tedium is better than just sitting around wishing it was warm outside!

Here's the real rub: no matter how much you might want to, you can't shortcut this process even just down to having a single "brew day." Do that, and you end up with doburoku, which is a very bad thing even for a lover of all things sour and funky like yourself. Trust me on this one, the result is horrible even if you manage to keep your fermentation temperature down. Learned that lesson the hard way, I did. =(

@Chris: Homemade sake will never be a yamada nishiki daiginjo, but it's definitely better than the boxed slop they pipe through the sake machine at the typical American sushi joint.

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