Grain Gelatinization

[higgins]

I'm trying to understand more about gelatinization of unmalted grains so I can maximize the extraction efficiency of my mashes. In order for the starch to be released from the grain (making it accessible by the enzymes) you have to get it into a specific temperature range. But I've still got questions.
1. how long does it need to sit in that temp range (assuming a fine grind)?
2. will it gelatinize at temps higher than the given range?
3. can gelatinization and enzyme conversion take place simultaneously, or does it need to be gelatinized first?

I found several charts that show various grains gel temps, but they aren't totally consistent.

GelTemps.gif

GelTemps1.png

Bamforth_GelTemps.png

The last one was created by Dr Charles Bamforth in 2006 (https://www.semanticscholar.org/paper/N ... 291fbe743a). I was an active participant in a discussion about yeast and fermentation on the Homebrew Digest (now defunct, but very active in the early 2000's) in which Dr Bamforth also participated, so I learned much from him and I respect his input.

So thinking that gelatinization of raw barley (126-138F) would occur while mashing, I did a mash a few weeks ago of 25 lbs barley malt and 25 lbs of raw barley at 132F for 1 hour, then 150F for 2 hours. My resulting efficiency was about 53% (I normally get about 75% with beer mashes). I'm thinking that the raw barley didn't undergo a complete gelatinization.

After finding Bamforth's chart, I did a similar mash yesterday (25 lbs raw barley, 30 lbs malt), but used 142F as the barley gel temp. My process was this:
mash the raw barley at 142F for 1 hour to gelatinize
add 1 gal cold water to reduce to 132F to prepare for protein rest
Add 30 lbs barley malt + 6 gal 143F water to rest 1 hour at 132F (protein rest)
Add 6 gal boiling water to rest at 152F for 2 hours (sacc rest)
Sparge with 11 gal 180F water.

The only real difference was doing the gel step 1st. It went much better this time, yielding about 76% efficiency. The fermentation is very active.

So I guess my answers to my questions would be:
1. some period of time - 1 hour seemed to work with barley
2. No
3. No, unless gel temp and mash temp are same.

Since my 132F step on the 1st mash didn't gel/convert the barley as much, and the 142F gel step on the 2nd mash DID gel/convert the barley, I tend to believe that Bamforth's temp chart is more accurate.

Any comments? (especially on the differences in the charts?)