By the description given of the origin of yeast, it appears that it is formed rather of the coarser oils of the worts. If the cleansing is not done when the head is sunk down to half the greatest height it rose to, by falling lower, some part of these coarser oils return into the beer, then under fermentation, and gives it a flat, greasy taste, technically termed yeast bitten. When, on the contrary, beers or ales are removed too soon from the first tumultuous fermentation, for want of having been sufficiently attenuated, and from not having deposited their lees, nor thrown up in flowers their coarser oils, they are less vinous, than otherwise they would have been, appear heavy, aley, and are said not to have their body sufficiently opened.
The fermentation of common small beer is, through necessity, carried on so hastily, that it is hardly possible to wait for the signs, which direct the cleansing of other beers. This drink being generally brewed and fermented within twenty four hours, its state, with regard to fermentation, is best judged of, by the quantity of its froth or head at the time of cleansing, which, in proportion to the heat of the air, may be determined by the following table.
A TABLE shewing the depth of head, which common small beer should have to be properly cleansed, in every season of the year.
| Heat of the air. | Head on the beer in the tun. |
| 25 Degrees | 6 inches. |
| 30 | 5 |
| 35 | 4¼ |
| 40 | 3½ |
| 45 | 2¾ |
| 50 | 2 |
| 55 | 1½ |
| 60 | 1 |
| 65 | ¾ |
| 70 | ½ |
| 75 | ¼ |
| 80 | just taken. |
As it is chiefly by the action of the air that wines are formed, if we contrive to shift this powerful agent on the surface of a must under fermentation, and to convey it more forcibly and hastily into the wort, its efficacy will be renewed, the fermentation accelerated, the liquor quickly become transparent, and soon be brought to the state of maturity age might slowly make it arrive at.
Amber, or pale ales, require the hottest extracts pellucidity admits of to be made strong, and at the same time soft and smooth to the palate; but, as ales do not admit of any large quantity of hops, which would alter their nature, there is a necessity to perform hastily the act of fermentation, and to carry it on to a higher degree than is common in other malt drinks. The method of exciting and conducting repeated fermentations, with success, is perhaps not only the most difficult, but the most curious, part of the process, I shall therefore conclude, with an account of it, what I have to say with regard to the practice of fermentation.
The amber wort being let down, at its proper degree of heat, into the fermenting tun, out of the whole quantity of yeast allowed for this drink, in the table, page 317, one seventh part must be kept to be used as hereafter shall be mentioned. Suppose the heat of the air is at 40 degrees, and eight quarters of malt have been brewed for this purpose; the whole of the yeast required is seven gallons, from which one is to be reserved.[39] Of the six remaining gallons, one half, or three, are to be put to the wort oh its first coming down, when the whole must be well roused, or mixed, thoroughly to disperse the enlivening principle the yeast conveys, hereby to prevent putrefaction, or foxing in any part, and of the last three gallons, about three quarts must be added to the drink, every twelve hours, until it ferments to the highest pitch of the period mentioned in article 5, page 319. This successive putting in of yeast is called[40]feeding the drink; before and about the time the head is got to this height, all the dirt or foul yeast, that rises on the surface, must be carefully skimmed off; it is easily distinguished from the pure white froth, by its color, and by the sinking of the head occasioned by its weight. Length of time might attenuate some of these coarser oils, in a less artificial fermentation, but as this help is not to be waited for, and every obstacle to pellucidity must be removed, the brewer’s attention to this point cannot be too great.—The head of the drink having reached its utmost height, the reserved gallon of yeast is to be used, in order to give to the ale a sufficient power to bear the repeated fermentations it is to undergo, by being beat in, every two hours, with a jett or scoope, for one quarter of an hour, so that the head on the drink is each time to be reduced to the least height it is capable of. This striking in being continued, the drink will periodically require it, and be damaged if it be neglected. After it has undergone more or less of these fermentations, in proportion to the heats of the worts and of the air, the brewer is carefully to observe, when the head ceases to rise to its accustomed height, and then to examine the drink, by having the jett filled with it at the bottom, and brought through the whole body to the top, a small part of which being poured in a handgatherer, he will see whether the lees form themselves in large white flakes, and readily subside, and be informed, by the taste, whether the sweet of the wort is gone off, and the ale become vinous. If these two circumstances concur, the drink is to be beat in with the jett as before, but not roused as porter or other beers are; for the lees, which in this drink are in greater quantity, would, by this management, so intimately be mixed with it, as with difficulty to separate themselves again, if at all. It is then time to cleanse it; but the casks, at all times, more especially in summer, must be well filled up with clean drink, that is, part of the very drink, which was cleansed, avoiding that produced in the stillings, as this, for want of standing a sufficient time, is always yeasty, and the yeast, being greatly attenuated by the working of the drink, easily dissolves in the ale, and renders it foul and ill-tasted.
As the right forming of amber ales is looked upon to be the highest pitch of the art of pale beer brewing, I have dwelt longer on this article than otherwise it might seem necessary, to shew the connexion there is between every sort of malt liquors: but it should be observed, the same method of fermenting it, is to be practised both winter and summer, varying only the quantities of yeast in proportion to the season; for where, in winter time, this drink is fed with three quarts of yeast every twelve hours, half a gallon will answer the same intent in summer. Upon the whole, the process is contrived to accelerate fermentation, yet, the more coolly and gently it is performed, the better will the ales be. I have before hinted, if Madeira wines were fermented in this manner, they would sooner become fit for use, more especially as they need no ferment to excite them. However, this method of forming drink to be soon fit for use, has, either through interest or prejudice, been taxed with being unwholesome, but upon what grounds, I must confess I could never yet discover, as no reason of any moment has ever been alledged for this assertion.