A spent grain analysis provides more accurate insight into brewhouse operations than the conventional calculation involving wort volume and extract content of the cast-out wort. The total extract (remaining extract) in spent grain consists of soluble extract and available residual extract. The soluble extract is that which can be washed out of the spent grain and is usually determined from the liquor squeezed or pressed from spent grain. The total extract is determined by boiling the spent grain and then performing an enzymatic digestion. The difference between the total extract and the soluble extract represents the available residual extract captured in the spent grain. These results indicate whether a low brewhouse yield is due to a less than optimal grist composition, an ineffective mashing procedure or incorrect lautering practices.
Calculation of the residual extract in spent grain from 100 kg of the malt bill
Spent grain
This calculation is intended for quality monitoring in the brewery and for determining total brewhouse yield. A precise calculation can only be made if the extract and moisture content of the malt is known.