Checking diastatic ability of grain?

[Epimetheus]

If I do an Iodine test and it shows complete conversion (nice yellow color, does not turn dark) does that mean I have gotten as much maltose as possible out of the grain, regardless if the diastatic ability is low or high?

The recent AG efficiencies have been low, like 50%. My process really is the same but I am using malted grains from a different source.

 

[ColoHox]

The iodine test will only show you if there is starch remaining in your sample, not what type of sugar it has been converted into.

Is your crush the same? High proportion of specialty malts? Most modern malts are, at a minimum, self-converting (ie. enough diastatic power to convert the starch contained within), although usually quite stronger, there are some exceptions of course. Munich malt and some british 2-rows can have low degrees lintner.

 

[brewfun]

If I do an Iodine test and it shows complete conversion (nice yellow color, does not turn dark) does that mean I have gotten as much maltose as possible out of the grain, regardless if the diastatic ability is low or high?

There are two parts to mash efficiency: Conversion and Sparge. These combine to give you a gravity.

A refractometer will tell you when your conversion is complete. The simplest explanation is that the gravity will stop rising when conversion is complete. An iodine test is incomplete for telling you about the conversion efficiency.

Sparge efficiency is the other half of the equation. Your sparge method will have some bearing on this half and certainly is the key to higher overall efficiency.

Since you didn't talk about your mash/sparge method, I can't be any more specific.

Beyond that, pH, temperature and some minerals can have a lot of impact on efficiency. These topics are covered with enormous detail in other threads and books.