How is Malt made?

Malting is the controlled germination of cereals, followed by a termination of this natural process by the application of heat. Further heat is then applied to 'kiln' the grain and produce the required flavour and colour. A basic rule is that for malt to be made, the barley must be capable of germination, so maltsters' source their barley with a minimum germination of 98%.

Barley image 1 before steeping

Barley image 2 after steeping with the root chit just showing.

Barley image 3 with germination almost completed, showing the green malt with its longer root growth.

A simple way to consider it is that a barley kernel is composed of three parts:

	Dorsal Cross section through a barley grain, with the embryo stained red by tetrazolium dye, showing that it is capable of full germination.

a) The embryo, or germ, which will eventually grow into the roots and shoots of the new plant.

b) The endosperm, comprising of hard insoluble starch, which is the food reserve to be used by the growing germ of the grain. The embryo produces enzymes which travel into the starch, breaking down the starch walls and changing the condition of the starch from insoluble to soluble. This change is called the "modification" of the barley corn. The process must be controlled by the maltster, otherwise the enzymic conversion will continue, and the soluble stach will be further converted to sugars, to feed the growing barley plant. This must be avoided, to prevent loss of useful brewing extract.

c) The husk, formed by two overlapping halves, which cover the grain surface, to protect the germ and endosperm.

The maltster's task is to get the endosperm modification to a certain point, and then stop the process, "locking it up" by the use of heat. The brewer will then "unlock" the process when he mashes his milled malt, and completes the conversion to sugars which will feed the yeast to produce alcohol, whilst other characteristics in the malt produce strong contributions to the quality of the final beer.

It is very likely that malting, as part of a brewing operation, was the first use of biotechnology by man. The development of brewing cannot be factually dated, but it is likely that the earliest process was the fermentation of raw grain, an accidental discovery. The next discovery was likely to have been the use of bread to produce a fermentable drink. Dr Briggs in "Malts and Malting" cites a Sumerian reference to kilning malt for brewing, which has been dated to around 2500 BC. We can therefore be reasonable sure that some form of malting was in use four thousand five hundred years ago, and that the basic process is relatively unchanged.

Although the use of the natural process of change within the grain, which is the basis of malting, has a very long history, only in the last fifty years have maltsters' gradually taken complete control.

That change has been brought about by the breeding and selection of the barleys best suited to produce malt, the knowledge of the physical and chemical changes that take place during the malting process, and the development of techniques for their most effective control.

The modern maltster is able to source the correct malting barley, and with a skilful use of water, air, heat and time can produce a wide range of malts which can differ in flavour, colour and many other parameters as specified by the maltster's customer.

In the UK most of the grain used for malting is barley, but a small quantity of wheat is also malted for specific purposes. For the purpose of this explanatory note all references will be to the malting of barley.

In the UK the significant stages of a maltsters' operations can be identified as follows:

1)Intake of the grain from the grower to the maltsters' facilities, after a careful evaluation of each load.

2)Prompt drying of the intake grain to a safe storage moisture, of below 14%.

3)Storage of the dried grain, for at least a sufficient length of time to allow it to overcome, after drying, the natural condition of germ dormancy, (perhaps six weeks plus).

4)Screening of the barley to produce an even size corn, and to remove dust etc.

A Steep filling with grain.

A Kiln being Loaded.

On the kiln the malt is first dried, and then 'cured', the latter taking place at a higher temperature, which stops all changes within the grain. Kilning is a complex procedure, which only uses variable combinations of air-flow and heat, but under very tight control. The temperature/air flow profile varies depending on the malt being made, and would be quite different, for example, for a lager malt compared to an ale malt. Kilning is still a high energy user. Historically, in traditional floor maltings with no energy saving devices, it could take as much energy to make a tonne of malt as it took to make a tonne of steel! Modern malting plant technology has reduced that to less than half.

The maltster's kilning expertise produces the final components that have been specified by the customer, the simplest of which is the colour of the malt.

The Finished Kiln.

8)Malt from the kiln is put through a machine known as a deculmer, to remove the 'culm' or small rootlets that have emerged from each kernel during germination. Malt culm is a co-product for the maltster, which can be sold as an animal feed, as it has a higher protein content by weight than the original barley.

9)The malt is then put into store for a specified period before being screened and then sent to the customer.

UK maltsters' have spent considerable time and effort in ensuring that their malt production is carried out to a very high standard, which is auditable. They have in place their own documented system of control, or are registered under the ISO 9000 scheme.

Risk analysis well understood, and the MAGB has drawn up a Hazard Analysis Critical Control Code of Practice Click here to load an Adobe Acrobat version of the guide

A glimpse of some of the changes in malting technology...Click Here to see both a traditional floor and a modern tower maltings