Spent grains
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Spent grains are the insoluble part of the mash at the end of the mashing process, along with the absorbed water. The wort is separated from the spent grains during lautering. About 1-1.3kg of spent grain remains for each 1kg of grist because spent grain is 70-80% water. The solids consist of mainly of husks and germ, along with other materials that do not go into solution or have precipitated again.[1]
Of the original grist some 17–22% of the original dry matter remains. This material is wet and, depending on the mashing system employed, contains up to 80% water.[2]
Solids content of spent grain:[3]
- 41% nitrogen-free extracts
- 28% protein
- 17.5% cellulose
- 8.2% fat
- 5.3% minerals
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The spent grain can be used as animal feed, composted, processed into flour for baking, or used as fuel (all of which is beyond the scope of this article).[4] Spent grain can easily spoil, so it should be discarded, dried, or frozen soon after brewing, and not left to sit at room temperature.
As they deteriorate rapidly, spent grain should be removed from the brewery as quickly as possible, to prevent it from becoming a source of undesirable organisms.[2]
- Variability of brewer’s spent grain within a brewery
- Phenolic Acids, Antioxidant Capacity, and Estimated Glycemic Index of Cookies Added with Brewer’s Spent Grain
- Sustainability: Recovery and Reuse of Brewing-Derived By-Products
- https://www.academia.edu/116494060/Review_of_the_valorization_initiatives_of_brewing_and_distilling_by_products
References[edit]
- ↑ Kunze p 265
- ↑ a b Briggs DE, Boulton CA, Brookes PA, Stevens R. Brewing Science and Practice. Woodhead Publishing Limited and CRC Press LLC; 2004.
- ↑ kunze p 285
- ↑ Marković I, Deponte R, Marić V, Johanides V. Enzymic hydrolysis of protein during barley spent grains mashing. Process Biochem. 1995;30(5):411–419.