The Use of Raw Barley in the Mash Tun

The Journal of the Institute of Brewing     (1941)

By Julian L. Baker, F.I.C.

It. has long been known that malt diastase attacks the starch granules of certain cereals with the formation of sugar.  Thus Brown and Morris (J. Chem. Soc., 1890, 510) stated that malt diastase had a solvent action on the granules of barley starch with the formation of maltose only.  Later the writer and H. F. E. Hulton (this Journ., 1914, 1529) found that over 40 per cent, of barley starch granules was dissolved in a few days at 37° C. (99° F.) by malt diastase, the products consisting not only of maltose as Brown and Morris claimed, but a mixture of that sugar with dextrins.  At higher temperatures short of the gelatinizing point of barley starch practically the whole of it was dissolved by malt amylase.

In the light of our more recent work on the action of malt diastase and starch (ibid.,-1937, 301; 1938, 514; 1939, 299; 1941, 344) the writer has little doubt that when malt diastase acts on barley starch granules or on starch paste the products are very similar in composition, i.e., at ordinary mash tun temperatures a mixture of maltose, malto-dextrin and stable dextrin are formed and at lower temperatures maltose and stable dextrin.

Whilst malt diastase attacks the starch granules of the cereals barley, wheat, rye and oats with ease at 37° C. (99° F.) maize and potato starch are far more resistant to such action.

A consideration of these facts naturally suggested that if barley be sufficiently finely ground the starch in it would be completely converted if it be mashed with malt at brewing temperatures. (According to Accum “Art of Brewing” published in 1820, distillers used a mixture of ground malt and barley in their mash tuns.)

The following figures support this statement.  Mashes at 150° F. of a mixture of 25 gms. malt and 25 gms. ground 1941 crop English barley were mode under the conditions prescribed by the Institute’s Standard Methods of Malt Analysis.  In one case barley was finely ground in a coffee mill and the malt in the Seck mill, in the other, barley and malt were both ground in the Seck mill.

Extract yield per 336 lb
of barley containing
11.5 per cent of moisture

Barley ground in Seck mill                                                                                         72.8 lb.
The same barley finely ground                                                                                    86.2 lb.

These figures show how necessary it is to have the barley in a finely ground condition if the maximum extract from it is desired. 

The filtrates were bright but filtration was not quite so rapid as when the malt alone was mashed.  However, for brewery practice it is not suggested that anything like 60 per cent, of raw barley should be used.  For the present, 5-10 per cent, of barley may be regarded as a maximum amount until experience and data are available as regards any mashing difficulties, effect on the yeast, and flavour of the finished beer.

In considering the practicability of using ground barley in the mash tun, the brewer will require some information as to the amount of permanently soluble nitrogen contributed by such barley when the wort is boiled.  Nitrogen estimations were made in laboratory mashes with malt alone and the same malt mixed with ground barley, the procedure followed being that formulated by the Institute’s Committee Method.  The grist comprised ¾ of malt ground in the Seck mill and ¼ of barley ground three times in a coffee mill.  After mashing, 200 c.c. of the filtered wort was boiled for 15 minutes, made up to volume, filtered and the nitrogen determined in 100 c.c.

The under-mentioned results were obtained:—

For purposes of comparison, figures for specimens of flaked barley from two makers and one of flaked rye are included.  The permanently soluble nitrogen does not differ greatly from raw barley, but the extract obtainable from flaked rye is higher than from flaked barley.

Brewers now have had some experience of flaked barley and the consensus of opinion appears to be that it can be used with safety in the mash tun in amounts varying from 5-10 per cent.  But it is a manufactured material and the costs of processing would be saved if ground barley were delivered to the brewery.  Ordinary malt mills would be useless for grinding barley as their action is only a crushing one and to obtain the available extract it has been shown that the barley must be finely ground.

Under the present war conditions the purchase of a suitable mill might be difficult and the barley would have to be ground elsewhere.

The next point which arises is the manner in which the ground barley should be mixed with the malt to avoid any difficulty in mashing.  The mixture must be an intimate one, otherwise the ground barley may “ball” into gelatinous masses and the filter plates of the tun become partially clogged.  Doubtless there are a variety of ways effecting the admixture depending on the grist case arrangements.  Where a flaked maize feeder is available there should be no difficulty, as the quantity of ground barley can be suitably adjusted to blend evenly with the malt.  The one essential point is an even mixture of the ground barley and malt.

No doubt criticism will be directed to the suggestion of the use of ground barley, but the fact remains that it will yield its available extract and trials on the brewery scale (5 per cent.) have confirmed this.  In some cases the taps were not quite brilliant all the way, but there was no starch in the last runnings.  The fermentations were normal and the beers fined well. Some observers considered there was a slight effect on the flavour tending to what was described as “softness.”

The Laboratory,
Stag Brewery,
Pimlico, S.W.I.
December, 1941

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