To simply state the obvious, malt is germinated barley (or other grains) that has been dried in a process known as malting.
The grains are made to germinate by soaking in water and then stopped from germinating further by drying with hot air. During the malting process, the grain develops starch degrading enzymes (alpha amylase, beta amylase and limit dextrinase) that are essential to modified starch into sugar. This process also develops cell wall degrading enzyme (beta glucanase, beta solubilise) and protein degrading enzymes (proteinase).
The supply and malting process
- Barley Intake & Pre-cleaning – to emptying the barley grain from transport through intake duct and to remove iron objects, large and small particles, dirt, cut awns, dust and light particle.
- Cleaning and grading – to remove the large components and small components (wood, sand), dust, awns form the barley.
- Steeping – to uptake and distribute of moisture and washing some microorganism, tannins, protein, acid, dust and loose particle from the barley grain.
- Germination – to produce enough enzymes (starch, protein degrading and cytolytic enzymes) and to limit the barley growth.
- Kilning – to stop the biochemical and biological processes by removing the water and by heating with hot air.
- Deculming – to remove rootlets because of it uptake humidity inside quickly, it has bitter taste, it can cause darker color and high concentration of free fatty acid.
- Storage – to keep it quality before sent to the customer.
Norsk Håndverksmalt – Malt system
As mentioned, the three main steps of the malting process are steeping, germination, and kilning.
Steeping is the first stage of the process, where barley or alternative grains are intermittently submerged in water for about 36-48 hours to initiate germination. The purpose of steeping is soaking and cleaning the barley grain from microbes, tannins, proteins, acids from the husk (can spoil taste of beer and cause haze). Biochemical reactions begin to take place in the steeping stage, as enzymes are released and simple sugars supply energy to the growing embryo. Barley moisture content at least 44% (pilsner malt 42 – 44 %, dark malt 44 – 47 %) after this process is completed and the germination stage begins.
During the Germination Stage, the steeped barley continues to grow and biochemical reaction occur at a vigorous rate, as enzymes are produced which break down proteins and other cell wall components. But before we look at this stage we will discuss the choice of design in Steeping vessels.
Design considerations of the steeping vessel
There are numerous sizes and shapes of steeping vessels, including; round, square, rectangular, conical (45º) or flat bottom.
The steep tank we will operate, will be conical in design and will cater for 5,4-tons of barley grain to be loaded into the steep tank. The tank will cope with a grain “swelling” of up to 1.4 times the original size. The original volume used in design was 23 to 30 mm3.
The grain float is separated during rousing with a blower which can then be removed via the weir to drain. Grain aeration during the “dry” period is downward suction via the CO2 fan. Therefore, carbon dioxide removal and grain aeration is incorporated into one system which will eliminate the problem of grain “heating”. A set of sprays are supplied to prevent grain drying out during air rests.
Steep out is through a centrifugal pump delivering medium volume at low pressure to ensure no shock is delivered to the grain during casting.
The steep operation is automated and comes with one standard steep recipe. Each step in the standard recipe can be adjusted.
*Allowance to (self) program 5 more steep programs is available.
Design considerations of the germination-kilning vessel
Germination Kilning vessels are combined vessels in the malting plant that link the last two of the three principal stages of the malting process into one. In a GKV, germination and drying occur within the same vessel without the need to transfer the green malt from a germination box to a kiln. Once germination is complete, the humidified air that was blown through the grain bed is replaced by hot dry air.
GKVs, like single-purpose germination vessels, come in rectangular or circular shapes. They need to be fitted with malt turners to keep the malt rootlets from matting together at the germination phase and to ensure proper aeration during aspiration. During germination, the turners ensure the proper rotation of the batch from top to bottom. This ensures the homogeneity of the finished malt.
GKVs tend to be completely automated. In a circular GKV, the floor carrying the grain may revolve instead, while the malt turners are fix-mounted and thus stationary.
The kilning heat is supplied through a steam boiler. The boiler is normally fired by either gas or diesel and includes automatic pressure controls, feed pump, burner, safety devices chimney, automatic water softener, blow down system and hotwell.
Chill water is supplied via a chiller to a conditioned water tank. This tank will supply water to the steep tank and or the humidification chambers at a wanted temperature normally around 15o Celsius.
The kilning heat will generally deliver air temperatures up to 120 Celsius. The heating control is automated via PLC ensuring various options available to the maltster.
The malt system could produce 50-tons of finished malt per month.
To develop a system, we have worked closely with a South African malt specialist and engineer over the last 10 months, who has been designing a system that can deliver a consistent product, with relatively low energy use requirements.
This system will be developed and built in South Africa and we will provide further details on costs, specifications and purchasing later this Summer (2016).
We are now an established cooperative trading under the name Norsk Håndverksmalt SA. We will be concentrating on developing the grower network throughout 2016 and will also prepare and establish supply contracts with future customers in the coming months.
If you are interested in supplying, Barley (or other grains) for our malt houses at the end of the season we would be happy to connect. Please email me directly if you are interested in supplying us with grain this year.
If I do not get the chance to wish you a great 17th of May “Ha fin dag”!
Until next month!