Crystal malt is said to positively influence head retention / foam stability in the final beer. Why is that?
Crystal malts add both head retention and body to the beer, they do this by adding dextrines and complex proteins. The crystal or caramel malts are produced by kilning the grains with up to 50% moisture content in the barley creating a crystalline sugar structure inside the grain's hull. They are undermodified malt and have very little diastatic power due to the amount of moisture present in the kilning process. They add complex sugars to the wort that are not fermentable thus producing residual sweetness.
I decided to make some very pale bitter ("golden ale") for a change, with no addition of my normal 250g of standard crystal malt.
So the only ingredient were
- my usual Maris Otter pale malt 2.5Kg/5 gallons,
- 100g pale rye malt
- 100g torrefied wheat.
That makes an everyday brew of about 3.5% alcohol.
The rye and wheat were added for flavour (rye) and improved head (Torrefied wheat) which I have been using for a long time.
The main effect of the crystal malt in my experience is that it darkened the brew a little, giving it a traditional bitter colour. I've never noticed any effect of the crystal malt on sweetness but it may add a little extra body. My unexpected finding is that leaving out the crystal malt has improved the head greatly. The head starts half an inch high and seems to linger right down to the bottom of the pint now.
I've made 3 pale malt brews now, without any crystal malt, and the result has been the same. For the record, for some years I've been adding 10g of powdered heading compound (from Bigger Jugs) which says it contains "maltodextrin and yeast elements" to the syphoned beer after fermentation and before bottling, which has helped a lot. But the effect of leaving out the crystal malt seems to have been a major advance.