. . . . . . .
Like all other worts, those intended to form this unique medicine require speedy cooling, which will prevent too voluminous an absorption of oxygen ; and hence the imperative necessity of an efficient refrigerator. They do not require more yeast than other worts of the same gravity, but it would be almost futile to attempt their fermentation without an attemperator; for it is absolutely necessary to conduct this process with the nicest regularity, since the ultimate purification and brightness will otherwise never be perfected. It is not needful again to allude to the peculiar kind of fermentation enforced by the subterranean expedient, farther than to observe, that nothing can equal its efficacy, and the uniform certainty which it will ensure in the manufacture of ales destined for a market such as that of India. The correctness of this remark, it is presumed, cannot for a moment be doubted; but the author will here confine the sphere of his operation to the provision of an ordinary brewhouse and common plant.
The malt should be of first-rate quality, perfectly dried, and very pale, colour being the first consideration in point of importance; and the hops should therefore be of the palest growth; and in selecting those that impart the least colour, their maturity should not be overlooked. The quantity must vary inversely with the quality; but as the flavour of this kind of ale emanates more from the aroma and bitter of this flower than from any other material, from the ultimate extreme decay of the malt extract, it is advisable that the hops should be of the description which contains the greatest share of condition in the smallest bulk reasons for which qualification have already been assigned (vide p. 247). Such as those designated Goldings, Farnhams, and the very best East Rents, may be used with advantage, and seldom less than 22 lbs. to the quarter will suffice.
. . . . . . .
The pitching temperature may be from about 56° to 60°, and the exciting yeast may be diluted with some of the wort, to which more may be added occasionally, as the worts are flowing into the square. The materials forming the extract, not being over-dried, or carbonised, on the kiln, or in the copper, will immediately evince symptoms of decomposition ; and in order that the elements which aid the fermentation may be preserved as long as necessary, the heat of the gyle should occasionally be curbed by the attemperator, particularly soon after the commencement, and when the attenuation becomes rapid; with which resolution it should be constantly watched, or inspected at least every 4 or 5 hours, by night and by day, during the first forty-eight hours, at the expiration of which period the heat ought not to be found to have increased more than 2° or 3°, and the saccharometer should indicate a diminution of 7 or 8 lbs. gravity. Should the attenuation and the heat not keep pace at this rate, as it probably may not if the water is of a quality to be termed hard, a little indulgence may be extended to the accumulation of a degree or two, or, which is preferable, the exercise of a little more patience may be introduced, and less frequent inspection will suffice as an equivalent for the extension of time. By the period when the attenuation has prograded to within one-half of the original density, the heat should not be allowed to rise above 62°. The remainder of the process will require very close attention; for as the attenuation approaches the crisis for its cleansing and purification from excrementitious matter, three-fourths of its saccharine being converted, the thermometer appearing rather below than above 64°, about one-half of the yeasty head may be skimmed off, and at the same time the tap of the attemperator may be turned off. When 2 lbs. more have disappeared, the skimming may be resumed, and about three-fourths of the head may be removed. The density will now be 6 lbs., and at least 2 lbs. more should be attenuated before the fermentation can be considered complete, and which, it is presumed, the previous skimming will not prevent. If any obstinacy is experienced on this account, a small quantity of its own yeast may be roused well in, and so much early skimming must be afterwards avoided. When, however, only 4 lbs. remain undecomposed, the gyle should be skimmed quite clean, and the cooling powers of the attemperator should be appealed to.
The stream and the heat of the gyle must continue to pass gently away, and the cleansing skimmer should be put into requisition whenever the light head thickens to within an inch deep.
All that now remains to be done, is to expedite the clarification ; and as we know that heat, or calorific repulsion, is a power opposed to aggregation, being as such repellent, a separater of particles, the attemperator should now be put in requisition to extract the caloric, and thereby encourage the natural affinity of each remaining azotised particle for the others, that through their gravitation, and combination, and ultimate quiescence, a speedy precipitation may take place, so that by remaining in this cool state a few days, it may be fit for the vat. To make this peculiar process the more perspicuous to the inexperienced, the author subjoins a few figures from the end of a brewing of his own, which may be taken as an example and tested as a guide. The square contains 200 barrels of wort, the gravity at pitching (commonly called density) was 24 lbs. per barrel, and the hop employed was East Kent.
Hours in square Heat of gyle Attemperator tap Attenuation Remarks 0 57º off 0
10 57.5º on
22 58º on 19.1
36 59.5º off 17.5
48 60º on 16
55 60º on 15.3
62 61º on 14
72 61.5º on 13
78 61º on 12.2
83 62º off 11.2
90 63º on 10
96 64.5º on 8.5
102 64.5º on 7.6 Partially skimmed 113 65º off 5 Skimmed closer 120 66º off 4.3 Skimmed quite close 134 60º on 4 Skimmed quite clean 150 52º on 3.9 Skimmed quite clean 160 50º on 3.9 Skimmed quite clean 190 50º on 3.8 Vatted one-half. Sent other half out.
This precise time of fermentation is impracticable with such waters as are termed " hard," or such as the Burton brewers use. In these cases higher pitching heats and a higher fermentation are necessary for general practice, or where it is desirable to complete the attenuation without vatting, on account, as before observed, of the obstinacy with which worts ferment when so constituted ; but with soft or medium water, the above Table may be followed with confidence and accuracy.
If found desirable, the attenuation may be carried a pound or two lower, as before suggested ; and by proper management, the trial may be made with safety. To avoid premature acidity after its arrival at the place of its destination, it is necessary that all matter tending to its turbidity should be removed by attraction and precipitation, and that it should not be racked for exportation until it has become perfectly bright. About half a pound of new hops per barrel might now be added. The very small quantity of unattenuated matter yet remaining, should be no more than just sufficient to supply enough of carbonic acid gas for the requisite effervescence during its limited decay, without causing the slightest turbidity at any time, and to prevent its accumulating in excess, after shipping, and endangering the safety of the cask, a porous plug or two should be inserted into the shive or near it, through which the surplus gas may escape."
"The theory and practice of brewing illustrated" by William Littell Tizard, 1846, pages 514 - 521.
There's so much detail there, I'm not sure where to start. Perhaps where he does. That there were three types of IPA: ones for export, ones for use as a medicine and ones for normal UK consumption. The ones for the home market were less bitter and less alcoholic, but sometimes from a higher OG, i.e. less well attenuated.
Tizard then stresses the need for strict temperature control during the fermentation, to be achievd by use of the attemperator. And the need for using the best raw materials. Pretty obvious, really.
He recommends soaking the hops in hot water for 8-10 hours before use. And, to avoid wasting much of their goodness, re-using the hops in Porter. 22 lbs of hops to a quarter of malt is, assuming the OG he gives of 24 lbs per barrel (1066.5º), about 6.5 lbs per barrel. Or a shitload.
The pitching temperature is quite cool and the wort isn't allowed to heat much during fermentation. The process was pretty slow by the standards of the day. Just shy of 8 days from pitching to racking. Porter was pitched a good bit warmer - around 64º F - and allowed to heat to over 70º F, sometimes almost 80º F. As a result, the fermentation was shorter and more violent.
The fermentation was allowed to completely work its way out and the beer to naturally drop bright. Only then was it racked for transportation to India. Clearly they were trying to remove as much fermentable material as possible before the voyage. Even so, the casks were only soft-spiled.
There you have it then. IPA the 1840's way.