Malt can be kept several years and will not lose its enzymatic power. The Swaen has a special process to guarantee a long shelf life.
When the germination time is done, the green malt has to be dried to ensure the best preservability. It is generally accepted that malt should be kept below 6% moisture. All base malts however will be kilned and cured between 4 and 4.5%. After transfer to storage and bagging, a maximum of 5% will not be exceeded.
Green malt (germinating barley) will have around 10 to 12% moisture, when dried at normal temperatures. In order to reach the preferred maximum of 5% , temperatures have to be increased. Water will then migrate from the core of the kernel to the outside, where it will leave the malt.
Once the malt has been cooled down, it has the tendency to go back to its earlier (higher) moisture. That is what we call hygroscopic. In order to prevent this, the malt has to be kept in huge silos. Only the very small top layer is exposed to air. That is why malt is never kept in flat storage.
There is one exception to the max 6% moisture rule: low coloured caramel malts. Caramel malts have a different process. The green malt will be saccharified between 60 and 80°C and then dried. In order to produce the low colours, extra heating is not possible. The water content will vary from 8% to 6% depending on the colour (10 to 60EBC). Once it has cooled down, this water will have a chemical bonding with the caramel.
Keep water and air away
Malt is packed in special bags with a polyethylene layer inside. This will prevent the kernel of taking in more water. Once the bag is opened, the malt should be used. Should you only need a small quantity – like roasted malts – it is better to keep the remainder in an airtight plastic container. This has another advantage: the volatile aroma compounds from caramel and roasted malts will not be lost.
The Swaen malt is best stored in a moderate temperate, low humidity, pest free environment at less than 20ºC or 68°F. It is best used within 6 to 18 months from manufacturing date, depending on the type of malt.