Malting Process

What is Malt?

Malted barley, or ‘Malt’ as it is most commonly known, is a wonderful package of starch, enzymes, protein, vitamins, and minerals plus many other minor constituents that provide the brewer and distiller with their main raw material.

60-65% of the weight of malt is un-degraded starch and malt contains all the key enzymes for starch degradation during the mashing stage of both the brewing and distilling process. These enzymes produce fermentable sugars to supplement the other key nutrients for yeast growth that malt provides. These include amino acids, vitamins, and minerals.

An infographic with three sections in a row. Section one has a large vat of grains with a water sprayer above it. The text below says "Steeping". Section two has the image of a grain seed with the word "Germination" below it. The third section has a vat with a cutout view of the grains being mixed and the word "Kilning" below it.

The top down view of a large vat of grains with a water spout above it.

1. Steeping

The purpose of steeping is to increase the moisture in the grain from around 12% to approximately 45%. This is achieved through successive immersions and air rests over a period of 1-2 days. During this process, the grain begins to germinate and therefore produces heat and carbon dioxide. In the immersion cycles, the grain is immersed in water and aerated to keep the level of dissolved oxygen in the water high enough so as to not stifle the developing embryos. In the air rests, the carbon dioxide is removed to control temperature and prevent the embryo from suffocating. Due to the varying degree of moisture tolerance of the different grains, steeping is a crucial step in the malting process. When the steeping process is complete, all of the grain should be evenly hydrated and show signs of chitting.

A concrete warehouse with many metal spouts hanging from the ceiling, dispensing grains into large piles.

2. Germination

The Germination phase is the growth phase of malting. Germination lasts 4-5 days depending on the product type being made. The germinating grain bed is kept at target temperature and moisture by providing a constant flow of humidified air through the bed at specific temperatures. The grain is turned regularly to prevent rootlets from matting and to maintain a loosely packed grain bed to allow even air flow. The maltster manipulates germination conditions based on the type of malt being manufactured.

A person's hands full of grains with a room full of grains in the background.

3. Kilning

Kilning, the third phase of malting, dries the grain down to 3-5% moisture and arrests germination. Large volumes of hot air are blown through the grain bed. By adjusting air flows and kiln temperatures, malts of different colors can be produced with varying flavor profiles. At the end of kilning the malt is cooled and the tiny rootlets removed before analysis and storage. The final malt is analyzed extensively according to malt type and customer profile. The malt may be dispatched in bags, in containers or in bulk.

The top down view of a man in a safety reflective shirt using a rod to stir a large vat of grains.

4. Roasting

Roasting takes place in two roasting drums after the germination phase. The roasters have a finished batch size of 1.8-2 tons. The average roasting time is 2 ½ – 3 hours with product temperatures of up to 335F (168C). The roasted malt is then transferred to the cooler and spends 35 – 60 minutes there in order to drop the temperature to 60ºF (<15˚C) and fix the color and flavor compounds. The malt is analyzed before storage and thereafter awaits dispatch to our customers.

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Maltster looking into the steep tank at the malting facility at Great Western Malting