This section explains why British barley was mostly low in nitrogen and why Californian 6-row barley had been so popular before the war.
This yeast trouble has been increasingly aggravated in recent decades by the tendency to use barley of very low nitrogen content. The new hybrid barleys which command by far the greater part of the British brewing market — Plumage-Archer and Spratt-Archer — have been selected, propagated, grown and manured with the object, among others, of reducing the nitrogen content of the grain. The reasons for this procedure are to be found in the brewers' fear of bacterial and of protein instability arising from the use of malt of high nitrogen content. Under the British system of brewing, a nitrogen content of upwards of 1.6 to 1.7 per cent of the moisture-free grain would be regarded as high in many quarters. Barleys as low as 1.2 to 1.3 per cent are commonly obtainable. Furthermore the low-nitrogen barleys normally have a better appearance and yield more extract, for which reasons they are more highly valued.
The result has been that farmers have been aiming over a period of years at producing a low-nitrogen barley in order to compete successfully for the high competitive prices obtainable for such barley. Very much of the malting barley grown here today is of this type, but the conditions of brewing are not always such that malt made from low-nitrogen barley is the right type to use. In some breweries and for some beers the grists, type of yeast and fermentation technique used may be ideally suited for these malts; in others, malt of higher nitrogen content might better be employed.
In normal times almost all British brewers use flaked corn or sugar as a malt adjunct. The former helps to give a paler and brighter beer; the latter aids clarification. Both adjuncts, however, reduce the proportion of yeast nutrients such as nitrogen, "bios" and minerals in the wort. The disappearance of the corn and reduction of sugar, and their replacement by malt extracts improved yeast nutrition until the effect of lowered gravities came into operation. The net result in most breweries has probably been that the one effect just counterbalanced the other.
In general, undernourishment of the yeast has not appeared in those breweries where it was not experienced before the war. Tolerably good yeast crops can be skimmed from worts of even the lowest original gravity, 1030 and slightly less. But in a few breweries yeast weakness is worse than ever. Lower gravities mean proportionally less nutriment per cc, but the yeast increase (including that which ultimately settles to the bottom of the fermenting vessel), is not proportionately less. Taken by itself, a very low original gravity leads to a markedly reduced top crop available for skimming, and to slight undernourishment of the yeast. In time the latter effect is cumulative.
There is normally less home-grown barley of good malting quality than is needed to meet the demand, so that some less satisfactory material is malted and used. In England most malt is not made by the brewer himself, but by a maltster who sells it. The latter naturally tries to buy barley of low nitrogen content which will malt easily. The brewer whose yeast is liable to undernourishment is more than ever in trouble today under these conditions. To brew the low-gravity beers he needs barleys of higher nitrogen content, but which modify well, and he cannot always get such as there is not enough to go around.
"Wallenstein Laboratories Communications, December 1943, Volume VI, number 19" pages 154 - 155.
I'd never realised that Plumage-Archer and Spratt-Archer had been deliberately manipulated to give them a low nitrogen content. (Plumage-Archer is the variety Fullers used in Past Masters XX.) I suppose it makes sense, if you expected to have Californian and other foreign barley available. If you knew cheap, high nitrogen barley could be found, it was logical to keep the nitrogen content of British barley low.
Another strange effect of the war was the increase in the proportion of malt in the grist. The flaked maize used in brewing had been imported. When the war began, the supply was cut off. The amount of sugar available for brewing was also reduced as it was diverted for other uses.
"In normal times almost all British brewers use flaked corn or sugar as a malt adjunct." This is often ignored by those trying to impose on the past their own ideas of what it should have been. Sugar in particular has been an integral part of British brewing since the 1860's. I've recently been collating information from Whitbread's brewing records of the late 19th century. This is a good one. Guess which of these beers contained sugar and which didn't: X Ale, PaAle Ale, KK (Stock Ale) , KKK, Porter, SS (stout) and SSS? The two cheapest beers - X Ale and Porter - were the only two that were all-malt. The sugar was in the more expensive beers.
It's funny what is reflected in the brewing records and what not. I knew all about the changes in ingredients. But the problems with yeast health I'd been totally unaware of. That's what makes this article so useful. It adds an extra layer of detail.