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Polishing Rice? 101? vs. "Just Buying It!"

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Pacifico

Post Fri Aug 28, 2009 2:16 am

Polishing Rice? 101? vs. "Just Buying It!"

Well, I am new to sake, read much, weighed the differences, reviewed a few recipes, ended up using Bob's recipe...thank you Bob Taylor, my first attempt is coming along nicely.
Okay, I volunterred to try it...Polishing rice...I first thought about trying 5 pounds later decided on 1/2 pound of Calrose rice for this small experiment.

1. Added it to a rock tumbler with a rubber drum, added brand new B-B's (copper) as a source of abrasion and went for an 8 hour tour.... Left the container for 8 hours, then the experiment disclosed that the rice did receive a polish which turned the rice grains to a grayish color. I would credit that color tone to the drum being a black rubber drum. There was a powder coating on the interior indicating that some of the abrasive materials (B-Bs) did cause some action, noted by the powder coating on the interior drum walls. (no water was used in the polishing)
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2. Separated the B-Bs from the rice grains. Then used cold water and washed the rice to a white color using a screen strainer. The rice turned to a white/translucent color with fracture lines in each grain. The rice grain does not appear smaller than the factory packed rice after the tumbling.
Image

3. Comparing the rice directly from the factory package, the rice was similiar in color, translucent in clarity to the experimented rice, but not with "fracture lines" as the experimented rice disclosed.
Image

4. Comparing the factory rice, I then washed a handful of the rice directly out of the bag. Prior to washing, it was noted that the grains showed no signs of the fractures in the grain. After a brief cold water washing, and allowing the grains to air dry in the shade, the fracture lines appeared.
Image

5. Comparing the photos, both grains showed very little to no difference in grain size, polished finish, and shape. Personally, I believe that this effort in the attempt to polish rice further from the factory packaged lot is fruitless unless done on a larger scale with more success...

For me, at the present, I rather use what is locally available, or go for the high-percentage polished variety offered by retail/factory outlets if affordable later..... Kokuho Rose is available here as well as others, so I'll ..."Just Buy It!"
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Taylor-MadeAK

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Post Fri Aug 28, 2009 2:25 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

You skipped the part where you weigh the rice immediately after tumbling (before rinsing!) to determine how much material was removed by the polishing effort. At this point I can only guess that you managed to polish it down by 5-10%.

A good try, though. Perhaps you can try it again with more rice and without the copper ball bearings? BBs aren't very abrasive (they're quite smooth) when talking about something as small as grains of rice, so I bet adding them really didn't contribute much to the abrasive action of the tumbler. Using more rice and allowing the greater weight of rice to act as its own abrasive might be the way to go.

Mind you, I've never used a rock tumbler, so I don't know what kind of abrasives are available for this use. If you use anything, it would have to be something completely neutral. Copper isn't a good candidate for that because you've just contaminated your rice with copper, which is toxic to yeast.

I would also be concerned about that rubber drum interior. I'm sure it's not toxic, but most types of rubber taste pretty awful. This doesn't matter when it's rocks that you're polishing, but we're talking about rice that you're going to add to a batch of sake...yuck! Do you have an alternate drum material that you can use? Preferably stainless steel or even ceramic?
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Pacifico

Post Fri Aug 28, 2009 9:49 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

Yeah, forgot to weigh after the drum roll. I'll go ahead and try it again sometime soon. I was doubful that the B_Bs would work because of the surface smoothness. I plan on dumping the rice and not even feeding the wild birds with it. I agree that the rubber drum would probably contribute an off-taste to the rice. It was really gray after tumbling. Being more concerned in hopes that the experiment would be successful not intending on using the rice. Bob, what's your take on the fracturing of the rice grains? Something to do with "expansion & drying?"

I am considering lining the drum with an abrasive sand paper 180 grit or so and tumble a pound to see....(will weigh in and out) how effective that would be. This time, just the rice itself tumbling on its own weight.

I don't have any other source of tumbing the rice. The interior of the drum is built in sections like a decagon vs. a smooth sphere. I would guess that this shape aids the tumbling effect as the drum rotates. For the matter of other materials, a wooden drum can be constructed with those sections previously mentioned and somehow rigged to a rotisserie unit or similiar application, and the interior walls with a adhesive applied abrasive such as what's applied on wooden stairs that appears like strips of sand paper for a surefooted step. Oh I'm running here...... :blah: :blah:
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Taylor-MadeAK

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Post Sat Aug 29, 2009 12:49 am

Re: Polishing Rice? 101? vs. "Just Buying It!"

Those cracks can be caused by a couple of different things.

First: You had a lot of metal balls in with the rice, which are much more dense than the individual rice kernels. Each of those BBs banging into rice grains over and over again will put quite a bit of structural stress on the rice. I'm actually rather surprised you didn't end up with more broken kernels instead of cracked ones.

Second: I've read that exposing the bone-dry polished rice to a lot of water immediately after polishing can result in fractured and broken kernels. The reason given was that rice milling uses friction, which creates a lot heat, which in turn drives off what little moisture is in that grain. So, if you follow milling immediately with washing and/or soaking, the rice will try to suck up that water so quickly that the outside of each kernel will expand much faster than the center - resulting in broken rice kernels.

Either way, you can find ways to minimize the fracturing and breaking.

Lining the drum with sandpaper would create an "abrasive type" rice milling machine. I hope it works. =)
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bee-yah

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Post Thu Feb 18, 2010 10:00 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

How is it done commercially?
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trex66

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Post Fri Feb 19, 2010 12:32 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

Here are a few home models on Amazon Japan - if you look at the first one, the 'Tiger one' it has a diagram that shows how it polishes the rice. Commercially, the bran is take of with a vertical, conical drum spinning around a stationary abrasive cylinder in the center. Then polished using a horizontal drum spinning around causing the rice to rub against each other and friction removes the rice particles. The drum has holes in it, like the home models do, so the rice flour falls out of the drum and is used for other things.

http://www.amazon.co.jp/%E3%82%BF%E3%82 ... 580&sr=1-1
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bee-yah

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Post Sun Feb 21, 2010 7:59 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

I couldn't figure out what to click to see the diagram, but found some pictures via google. Still couldn't grasp the source of the abrasion though. I wonder if some 220 grit taped to the inside of the box would help the clothes drier method. A few spritzes of water might help avoid cracking the grains.
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bee-yah

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Post Sun Feb 21, 2010 8:06 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

Just realized that the paper would probably clog with flour. Maybe a container-within-a-container with some small holes in the inner container to let the flour out. Except that the flour could just as easily pass back in to the inner container as it could pass out. Maybe a shop vac rigged to a sanke keg somehow, rolling on some wheels. Just throwing out ideas....
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willauld

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Post Sun Feb 21, 2010 8:13 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

Now you are thinking!
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gemils

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Post Tue Mar 09, 2010 2:22 am

Re: Polishing Rice? 101? vs. "Just Buying It!"

I have been looking at some of the commercial rice polishing machines at alibaba.com. They happen to sell a lot of commercial and imported equipment, including variations of these devices. One of the interesting notes that I saw on a couple of the listings indicated that you should have the rice up to "16% moisture" before polishing. How one defines 16% moisture is a little confusing, but may lead us down a path to more polish and less cracking. It makes some sense that a lightly moistened outer layer on the rice would be more readily stripped from a harder core.

I am wondering if there is a way to make a multi-layered screen polishing container that would fit into a basic tumbling set up ... inner core of the tumbler has perforations that are about the size of your 60% polish, which dumps out onto a finer mesh, allowing your rice flour to fall through, your polished rice to get collected, and the rice that hasn't been polished enough to keep on rolling.

This, of course, assumes that we can get satisfactory results by tumbling.
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willauld

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Post Sun Aug 01, 2010 10:27 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

I just put together a post on my site http://homebrewsake.com/2010/08/01/milling-your-own-rice-with-the-twinbird-mill/about using a home rice milling machine from Japan. The machine is meant for preparing table rice. So, I was mostly trying to see if it would work for sake. While it is a pain, in that it would be very time consuming, it can be used.

I don't have a camera for at least a couple of weeks so I will not be able to produce pictures for a while. If you want to see anything specific I will try to get them.
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Taylor-MadeAK

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Post Mon Aug 02, 2010 7:33 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

That...is an amazing article, Will! Well-written and full of useful facts. Good job!
Primary: Nothing. Gainfully employed now, but still broke.
Secondary:
Bottled: Saké 2010
Make some sake.
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willauld

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Post Tue Aug 03, 2010 9:19 am

Re: Polishing Rice? 101? vs. "Just Buying It!"

Thanks Bob!

One thing I meant to mention but didn't was the aroma from the rice while milling. While I had heard rice had a perceptable aroma while milling I had not noticed it ad SakeOne when I am there and they are milling. While milling the rice on Saturday there was a distinct (I want to say strong but that is of course a relative term that may be too strong itself :o) fruity floral aroma that was quite plesent. I was a little surprised at first and only later remembered that I had heard people mention this about milling table rice.
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gemils

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Post Wed Aug 04, 2010 5:13 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

I agree, this was a great article. It raises some of the questions that have been discussed elsewhere on this thread, and I wonder if you might be able to speak to some of them:

-How does it work (folks theorized nested cylinders, drums, abrasives etc)?
-Do you need to moisten the rice before milling to prevent cracking?
-Any thoughts on how we might be able to make one on our own?

Not that I need yet another project, mind you, but inquiring minds need to know!
Primary - Sake
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Bottled - Soon, soon ...
On Deck - Mead, more Sake
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willauld

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Post Wed Aug 04, 2010 5:30 pm

Re: Polishing Rice? 101? vs. "Just Buying It!"

gemils,

I think that some pictures will be helpful in understanding how it works. For the most part it has a steal mesh basket that the rice sits in with a propeller inside the basket that throws the rice around. So the pollishing is from rice on rice and rice on basket walls. As all the rice is spining around the basket the nuka has an opportunity to leave the basket through the weave.

No moisture is needed.

In terms of making something like this, well it may not be that hard. Need a rigid mesh that could be molded into a circle to form the wall of a drum and a pattle or propeller to throw the rice around the drum.
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