Pilsner, pale ale, 2-row, Maris Otter — the diastatic base malts.
Munich, Vienna, aromatic, melanoidin — kilned darker, measurably more acidic.
Wheat, rye, oats and unmalted adjuncts — less acidic than barley base malt.
Crystal/caramel malts, whose acidity tracks their colour.
Chocolate, black, roasted barley, Carafa — the most acidic malts in the grist.
Acidulated / Sauermalz: base malt carrying lactic acid.
No contribution to mash pH.
Which titration curve a malt follows in the mash-pH model.
The class picks the default DI pH and buffering capacity. Measured values from a catalog entry override both, through the other fields on FermentablePhProperties.
nonemeans the fermentable adds no acidity and no buffering. It's used for sugars, and for extracts, whose wort pH is already set.