Malting
Malting
Main page
799029

Malting

logo
Community Hub0 subscribers
What are your thoughts?
Be the first to start a discussion here.
Be the first to start a discussion here.
Malting

Malting is the process of steeping, germinating, and drying grain to convert it into malt. Germination and sprouting involve a number of enzymes to produce the changes from seed to seedling and the malt producer stops this stage of the process when the required enzymes are optimal. Among other things, the enzymes convert starch to sugars such as maltose, maltotriose and maltodextrines.

The malt is mainly used for brewing or whisky making, but can also be used to make malt vinegar or malt extract. Various grains are used for malting, most often barley, sorghum, wheat or rye.

Several types of equipment can be used to produce the malt. Traditional floor malting germinates the grains in a thin layer on a solid floor, and the grain is manually raked and turned to keep the grains loose and aerated. In a modern malt house the process is more automated, and the grain is germinated on a floor that is slotted to allow air to be forced through the grain bed. Large mechanical turners, e.g., Saladin boxes, keep the much thicker bed loose with higher productivity and better energy efficiency.

The grain is received at the malt house from the farmer. It is taken in from the field and cleaned (dressed), and dried if necessary, to ensure the grain remains in the best condition to produce good malt. It is tested to check for suitability for malting and to prevent dead or unfit grain from entering the process. Typical quality checks include:

Barley received at the malt house with moisture of more than 13% must be dried before it can be safely stored without loss of germinative capacity. The moisture is removed by circulating heated air (up to 50 °C) through the grain and can either be performed using dedicated grain driers or as a batch process using a kiln. High temperatures or over-drying will damage or kill the barley embryos and the grain will not germinate after steeping. The dry barley can safely be stored for up to 18 months without fungal growth or loss of grain vigour.

The aim of barley cleaning is to remove foreign matter (straw, chaff, dust and thin corns) found in the incoming grain, leaving only the grain most likely to produce a good malt. Magnets are used to remove ferrous metals from the grain, in turn reducing the possibility of sparks, which could lead to a dust explosion. Rotating and shaking sieves are used to remove unwanted foreign matter either larger (straw and un-threshed ears) or smaller (sand and thin corns) than the normal barley grain. During the sieving process an aspiration system removes the dust and chaff. De-stoners or shaking screens are used to separate small stones from the barley. The stones, which are denser than the barley, move out the top of the machine and the cleaned barley exits at the bottom. Half corn separators may be used to remove broken kernels. Half kernels need to be removed as only the one half will germinate and produce enzymes. At the end of the cleaning process the grain is weighed to determine the cleaning losses (the difference between the weight of grain received and the weight of the grain after cleaning) and it is transferred to a silo for storage.

The barley must be safely stored to maintain the grain vigour for germination. Storage at a malt house is normally in vertical silos made of steel or concrete for ease of use, but may be in flat stores when large amounts of grain is to be stored. The grain is stored in a manner that protects it from moisture and pests. A typical silo will store between 5,000 and 20,000 tons of clean dry barley ready for malting.

During storage the temperature of the silo is measured and monitored over time as a temperature increase can indicate insect activity. Additional equipment may be used to keep the grain temperature below 18 °C to inhibit insect growth. Silos are normally fitted with a system for rotating grain from one silo to another to break-up hot spots within the grain. A fumigation system can be used to administer a fumigant (normally phosphine) to the silo.

See all
User Avatar
No comments yet.