Alkaline Brewing Waters

From the Journal of the Institute of Brewing  1922


Some practical experiments, described by E. Bekaert in the Bull. Ass. Anc. Elites de l’Institut Sup. de Fermentation de Gand, give actual results and figures bearing on the principles enunciated by Fernbach.  He was dealing with some unusually alkaline waters derived from artesian wells in Belgium, containing in two cases 42 and 53 parts per 100,000 of sodium carbonate respectively.  On the other hand, their total and permanent hardness were only 10 and 2 degrees for the one, and 4 and 1 degree for the other. These waters were quite unfit for brewing on account of their high alkalinity.

Bekaert made an experimental mash in the laboratory with the second of these waters containing 53 parts per 100,000 of sodium carbonate, and a malt that saccharified under normal conditions in 20 minutes, and had an acidity to phenolphthalein corresponding to 0·153 gm. sodium carbonate per 50 gm.  He found that saccharification was not entirely complete in 3 hours, and that the extract was reduced by 6·5 per cent. The 200 c.c. water used for this mash contained 0·1 gm. sodium carbonate, that is to say, would neutralize 2/3 of the acidity of the malt.  In another mash ho used a malt with greater acidity, 50 gms. were neutralised by 0·19 gm. sodium carbonate, and saccharifying in 15 minutes.  In this case half the malt acidity would be neutralised by the mashing water.  Saccharification took 2 hours, and the extract was reduced by 2·9 per cent.

That these abnormal results were caused by the neutralising effect of the alkaline water, was proved by making mashes with the same malts and distilled water in which 0·1 gm., sodium carbonate had been dissolved in 200 c.c.  The results were the same in both cases.

In practice, the trouble caused by alkaline waters is even more noticeable than in the laboratory mashes.  Dextrins and starch are found in the worts and last runnings, and the fermentations are sluggish.  The effect of brewing with waters containing a high proportion of alkaline earth salts is not so bad as that produced by the alkaline salts, but the reduction of the extract and of the enzyme activity is still quite marked.  Bekaert found some years ago that, by brewing with a water rich in calcium carbonate and sulphate, with a total and permanent hardness of 84 and 40 degrees respectively, that the extract was reduced by 2·5 per cent., and the optical activity of the wort was higher by about 4 degrees, on account of the reduced diastatic activity and lower proportion of maltose formed.

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