Anything I’m Fermenting

February 14, 2012

Sake pt 2: Fail!

Filed under: Brewing,Sake — iwouldntlivethere @ 4:23 am
Tags: , , , , , ,

Fail! Just want to report and discuss the failure of the koji batch.

I didn’t take photos, but after 12 hours the koji was looking great – starting to stick together, getting a good covering of white fuzz. Then… it flat-lined. The white fuzz disappeared, the rice just looked like boiled (n.b. – not steamed) rice; it smelled nice and koji-ish, but wasn’t sticking together. It just didn’t feel right. I gave it an extra two days, but nothing changed, so I composted it.

I wasn’t obsessively monitoring the temperature, but I did notice it go up to 103F once. However, my suspicion is that it over-heated. Unlike in Bob Taylor’s method, where the rice is spread out on a plastic tray, I tried using a ziplock bag. I believe that this reduced the surface area of the growing koji enough to enable it to create enough internal heat to cook itself. Also, there’s a photo on the Ontario Spring Water Sake Co’s homepage of a cake of koji – it isn’t very thick, maybe 1.25 inches. Considering the size of koji batches they make, where growing the koji in thicker cakes would save a lot of space, it must be important to them to keep the cakes thin. The over-heating hypothesis also explains why the koji failed after apparent success – it took the first 12 hours to build up enough cell mass to generate heat. Live and learn; good thing I have lots of koji-kin!

I’m trying again, but with the rice spread out in two plastic containers:

It's just two trays stacked on top of each other.

The lids are not closed, they don’t even fit well into the cooler, so there is a lot of air exchange. They’re mostly there to keep condensation off the rice.

Here’s the thickness of the rice (very fluffy at this point):

You’ll probably notice the brownish spots in the photo. I absentmindedly forgot to close the lid of the koji-kin jar when I was innoculating this batch, and about 20 g of koji-kin rice fell in. I just went with it and mixed it in and hope this is enough innoculant, and that nothing bad will happen.

I’ve also been thinking about the placement of the thermometer probe in the rice. My feeling is that putting it in the middle of the rice means that the outside could get pretty hot before the heat reaches the middle. However, once the koji is generating its own heat, if the probe is not in the middle, it will not be measuring the maximum temperature. Not sure what to do yet.


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