Barley by itself can not be fermented.  It needs to be converted to malted barley.

The process of malting involves soaking the barley, allowing it to germinate, and then stopping germination with heat.  This process creates enzymes that will break down starches into sugars,  It does this fairly rapidly when both the malt and the starch material are heated in water. 

How the break down works; the starch is comprised of a chain of molecules bound together.  The yeast used to make alcohol only eats single molecules.  It can’t each a chain of molecules.  So this chain needs to be broken down.  This breakdown to a single molecule is done by the enzymes.  The broken off molecules are now a sugar and the yeast cells are able to eat them and produce alcohol.  

It is the preferred grain for making beer.  All the color in beer comes from the malted barley. A lightly-roasted malt will produce a very pale beer. Deeply roasted malts produce dark or black beers.

Barley

Barley by itself can not be fermented nor can it help other grains to break down sugars.  Barley needs to first be converted to a “malted” Barley. Then it will contain the enzymes that will break down linked chains of sugar molecules into single and unlinked sugar molecules.

Malted

The process of malting involves soaking the barley, allowing it to germinate, and then stopping the germination with heat.  This process creates amylase enzymes in the barley kernal that will break down starches into sugars,  The breakdown occurs fairly rapidily when both the malt and the starch material are heated in water. 

Malted barley has a diastatic power of 160 for 6 row barley and 140 for 2 row. It only takes 30 diastatic power points to convert the starches inside itself to sugars. So the balance diastatic enzymes remaining is used to convert other grains. Without the use of malted barley, alpha amylase enzyme solution would need to be introduced to break down the starches in the grains to sugars.

Enzymes

The starch is comprised of a chain of sugar molecules bound together.  The yeast used to make alcohol only eats singular sugar molecules.  The yeast” swallows” a single sugar molecule but can’t eat any part of a linked chain of molecules.  So this linked chain needs to be broken down into many single sugar molecules.  This breakdown of the chain links between single sugar molecules is done by enzymes.  Once sugar molecules are broken off the chain, the molecules are a single molecule free floating and the yeast cells are able to eat them and thus produce alcohol.  

Barley is the preferred grain for making beer.  All the color in beer comes from the malted barley. A lightly-roasted malt will produce a very pale beer. Deeply roasted malts produce dark or black beers.

2-row malt has a fuller, maltier flavor while 6-row produces a grainier flavor. 6-row typically has more protein and enzyme content than 2-row, is thinner, and contains less carbohydrates. There is a lower lower diastatic (enzymatic) power of two-row, max around 140 Lintner. It doesn’t have as much left over enzymes to convert adjunct starches like rye and corn.

6-row is only grown in North America. The scale that is used to determine the diastatic power of a grain is Lintner. 6- roe has a Diastatic Power of 160 per pound. All your un-malted grains have a diastatic power of 0 per pound. You need a diastatic power of 35 min, preferably 40 per pound in a mash to ferment all starches. The rule is put in 25% of what your total un-malted grains are in the mash. It will equal 20% of the total mash batch.

Barley has little glutten in it. It has a mild taste ideal for malting to create enzymes to break down starches.