A Practical Treatise on Brewing/Boiling
OF BOILING.
Various opinions exist as to the boiling of worts. Some think that long boiling, particularly of the second worts, tends to make the beer continue sound. We are not, however, aware of any preservative quality imparted by long boiling; but on the contrary, many injurious effects may be produced by over-boiling, some of which shall be afterwards considered. Long boiling, with free evaporation, undoubtedly adds to the strength of the worts, in proportion to the extent of the evaporation, and thus enables us to made a greater extract from the malt than we could otherwise do, particularly in brewing very strong beers. But where a raw or return wort is taken for next brewing, little or no advantage can be derived therefrom. Mr. Morewood says that at Louvain, in Belgium, which is rather celebrated for its beer, a portion of quick lime is thrown into the worts when boiling, —a very good thing—but soda would be preferable.—Morewood’s Inebriating Liquors, p. 257.
An erroneous opinion often prevails, that a portion of the saccharine matter of the worts is evaporated along with the steam in boiling. This opinion may have arisen from a mistake in calculating the difference of the extract as shown by the taps, between these taps, and the actual gravity of the boiled worts in the gyle-tun—or the difference, as some call it, between the raw and boiled gravities. An erroneous method of calculating the extract per quarter is followed by some brewers, who value the gravity of the worts as they flow from the mash-tun, instead of taking the gravity of the worts from the coolers as they go into the fermenting tun; thus showing a disparity of from 10 to even 20 per cent. more than the malt actually produces. We shall, however, be able to show, when we afterwards treat of extracts, that both gravities, if properly taken, must be precisely the same, only deducting for the quantity retained by the hops in the different boilings, which is afterwards transferred from one wort to the other in regular progression, so as ultimately to leave in the hops only a very trifling portion of the extract.
There is also a difference of opinion as to the use of open and dome coppers. For fine pale ale, there can be very little doubt that open coppers are preferable, although dome-coppers, (where a free evaporation of steam is allowed without much pressure) can do little harm. It is to be recollected, however, that in proportion to the perpendicular column of worts in the copper, and also to their greater specific gravity, charring will take place. Where, however, a considerable weight must be raised before any steam can escape, as in steam-engine boilers, considerable injury may arise, not only in the boiling of ale worts, but also of porter or stout worts; arising from the following causes.
In the first place, owing to the high pressure of steam, which must necessarily take place before the weight can be raised to allow of its escape, the evaporation of the worts in boiling is so trifling as to prevent the necessary increase of gravity, so as to enable the brewer to turn the proper quantity of liquor over his malt in the mash-tun, for producing the best extracts, particularly for beers of high gravities.
2. The weight to be raised before any escape of steam can take place, and the consequent high pressure, must necessarily raise the temperature of the worts in the copper far above the boiling point. This must, therefore, to a certain extent, alter the component parts of the worts, by charring or carbonising them. That this effect is produced, is sufficiently proved, not only by the brick-red colour of the worts when coming out of the copper, (although brewed from the palest malt,) but also by the beer, which can never have that fine pale or amber colour, so highly desirable for all sorts of ale.
3. The above-mentioned high temperature must also be to a certain extent injurious to brown beer, as it extracts from the hops an astringent bitter, by no means palatable, and to many highly disagreeable. This may not in stout or porter be very perceptible, but in fine ales it is particularly obvious.
Of Charring the Worts.
It has also been observed, that when the worts are thus charred, the fermentations are very much inclined to get fretful at certain stages, thus endangering the quality of the beer. We have ourselves lately seen this effect produced, but immediately afterwards remedied by withdrawing the pressure. We are not at present prepared to say what may be the chemical causes of the above-mentioned fretful fermentations: perhaps the charring of the Worts may so alter the nature of their component parts as to produce this effect.
But fermentations, generally speaking, are so apt to be influenced, by what, to many, would appear such trifling or even improbable causes, that they who have had an opportunity of seeing and tracing all their different anomalies, in their various stages, can alone find out and apply the necessary remedies.
Long or Short Boiling.
It must now be apparent that we are not advocates for long boiling, excepting as above stated, for the purpose of giving strength to the wort by evaporation. Long boiling can only be necessary when no raw wort is taken, to enable us to turn a greater quantity of liquor over the malt for the purpose of extract. As, however, a considerable portion of this additional liquor must be evaporated from the copper for the purpose of acquiring strength, perhaps the additional expense of coals and wear and tear may counterbalance any profit, which we may think we have derived from the little additional extract, we have thus gained from the malt.
We have had occasion to brew a good deal of beer for the Indian market, and we never on any occasion boiled the first Worts more than one hour, or the second worts more than an hour and a half. In the Appendix will be found the reports received from Calcutta respecting some of it, which will show that notwithstanding the shortness of the boilings, the beer turned out well.