Evaluating the Crush
work in progress
--Kaiser 22:00, 24 December 2007 (CST)
When brewing all grain, the quality of the crush has a major impact on the brew house efficiency as well as the lautering process. In extreme cases, a poor crush can also lead to astringent off flavors.
The ideal crush for malt exposes all the endosperm as flour and grits and leaves the husks intact. But in practice this is difficult to achieve. In order to expose as much of the endosperm as possible, the malt has to be crushed very tightly which leaves most of the husk material shredded. This can lead to stuck sparges astringent off-flavors. Conversely, when the malt is milled loosely the husks are preserved better but a considerable amount of the endosperm remains unexposed which will result in a loss off efficiency. Because of this the brewer needs to find a good compromise for setting the grain mill spacing.
The following pictures are intended to guide the brewer in evaluating the crushed grain: