Avoiding lautering problems
A common solution to lautering concerns is to add empty rice hulls into the mash. This extra husk material decompresses the lauter bed by creating more porosity. Increasing the porosity will allow wort to pass through without compacting the lauter bed and “blinding” the lauter screen. This is what we prefer as brewers, a smooth and fast collection of first runnings, followed by a steady hot rinse, aka sparge.
Larger vessels may incorporate rakes to aid in lautering. Raking the lauter bed can increase porosity and improve extraction, however too much agitation can lead to fine particulate, hindering efficiency.
Using a coarse mill setting is another option to increase permeability and prevent lautering problems, however conversion efficiency may suffer. If starch granules are not exposed to hot water, they will not hydrolyze and be exposed to enzymatic activity. This can be particularly concerning since unconverted starch will not ferment, causing lower attenuation and impacting colloidal stability.
The heating and hydrolyzation of non-barley grain almost always requires temperature above the active range of starch-converting enzymes. This means that rolled or flaked ingredients have virtually no enzymatic power, and must be accompanied to create a fermentable wort composition. Previously, the only viable option was to combine adjuncts with barley-based mashes in order to provide the enzymatic activity. Even then, care must be taken with percentages, temperatures, and hydration ratios. If too little enzymatic activity is present, conversion can take extended periods, or may not happen at all.
Why would you want to include gelatinized ingredients without enzymatic activity? With the gelatinization done, high molecular weight proteins and lipids can be solubilized into the wort, increasing mouthfeel and foam stability. The non-enzymatic properties can increase attenuation limit and influence haze formation, in some circumstances. Depending on the process, these attributes can be compromised when malting.