First post. I found this forum by way of internet search for information on baking bread with barley malt flour. I found a few threads on here about the subject and I wanted to share some information that may be helpful.
Malted Barley typically has the highest diastatic power of any malted grain.
Diastatic power is a measure of the enzymes in the grain that convert starch into sugar.
Alpha-amylase and Beta-amylase are the enzymes. (main enzymes, there are others)
They work best between 155 and 165 degrees Fahrenheit.
When I make beer it takes about 40 minutes to an hour to convert all the starch. If you include the Malt flour throughout all of your flour there should be plenty of time for it to convert some starch into sugar.
The lower the diastatic power of a malt the more you would add to get the same conversion.
This is very simplified but adequate information for baking purposes. If you want to learn more about starch conversion (sacharrification) search for "how to brew" by John Palmer. There is a free online PDF (published by Palmer) but I don't want to come off as advertising in my first post.
I hope this was helpful. Now off to search the forums for ideas on buying wheat for milling and baking at home.