I was wondering if anyone had a scientific explanation to this. During episode #42 of Brewing TV
at the 8:55 mark Jeremy King explains that his mash has converted because the bubbles have a rainbow appearance and the grain has a viscous feel. Is this an accurate indicator for proof of conversion?
I believe that the mash gets flooded with inverse tachyons while in a non-coupled state…okay, I have no idea. 
Seriously though, I would guess it has something to do with a certain levels and/or kinds of starch. Now you’ve got me wondering why. We need a beer science guy!
I’m starting to lean towards quantum tunneling. 
There are more epiodes where they delve into this.
i think it’s the big beer brewing episode.
IIRC it’s the starches and sugars :cheers:
And here I thought that it was because I used to used a sponge with a little bit of detergent on it to clean my mash tun. I couldn’t figure out how, after many uses and cleanings without detergent, I still got iridescent bubbles.
One less thing to worry about.
You’ll get diffraction in any thin film with an index of refraction >1. Granted, the effect will be more pronounced the higher the RI, but the difference is so tiny (10^-3 order of magnitude) for various worts that I don’t see how it could be diagnostically useful.
Unless someone has an explanation, or at least some data, I’m calling shenanigns.
Starch doesn’t dissolve into water but sugar does, so the refractive index probably does change appreciably and I could see this being the explanation of the observation. Apparently a bubble is kind of like a little refractometer. Also, I wouldn’t doubt that more bubbles would form as the sugar content increased.
I’m really struggling with this. Water is 1.333 and worts range up to ~1.35 depending on gravity. So more bubbles, maybe, but that’s a difference of less than half a degree in the refraction angle even at the outside, and I’d have to see some evidence in order to accept that the human eye can pick up on that.
So I’m mashing in tonight. While giving the mash a good stir, I notice the bubbles aren’t iridescent. After pouring in my sparge water, they are. I can’t explain the physics behind it but there does seem to be some validity to the claim.
BTW, you know you’re getting old when you used to stay up late drinking beer, now you stay up late making beer.
