Fining Difficulties

FINING DIFFICULTIES (paper delivered 1944)
By J. A. Burns, A.R.I.C.

Fining difficulties have been attributed to the following causes: —

(1) Presence of wild yeast: bitter beer containing over 0·5 million cells of wild yeast per cc. will be hazy and will remain hazy after fining. No isinglass, nor any auxiliary material will fine a beer containing a heavy infection of wild yeast. In fact, from the practical point of view, a wild yeast can be defined as one which will not take finings.

(2) Excess of primary yeast. If a beer is working actively it will not fine because clots are broken up before they can settle. When this activity has subsided, it will often fine quite satisfactorily. In one case a cask of bitter beer with a yeast content of 30 million cells per cc. would not take finings, but when cask fermentation had subsided it fined tolerably bright.

(3) Beer racked too clean. If finings are added to a beer containing very little suspended matter the resulting coagulation is so meagre that floating pieces are apt to remain in suspension. Another form of this trouble is described as “fining in layers,” which is directly attributable to lack of condition in the beer, but as this is usually due to a lack of yeast in suspension it can be referred to exceptional clarity at racking and can often be traced to indiscriminate use of copper finings. These faults, due to lack of yeast in suspension, may also occur when casks are allowed to stand for a few days un-fined, then finings added and allowed to act without rousing up the yeast at the bottom of the cask.

(4) Fining under pressure. If a cask is not vented during fining the beer may become heavily supersaturated with gas and when drawn the sudden rush of gas from the bottom of the cask disturbs the deposit and after at first running bright the beer becomes very piecy, or even thick.

(5) Chill haze. This is due to cooling a beer below the temperature at which it was fined. Usually a drop of 5 to 10° F. will produce a haze which may persist after the beer is warmed again to the fining temperature.

(6) Stubborn fining. Some beers, though free from wild yeast, and satisfactory as regards condition and content of primary yeast, will refuse to fine bright when newly racked. Sometimes the finings give a break, but the beer remains hazy. More usually there is no break and addition of finings seems only to increase the haziness of the beer. In these cases, Irish moss auxiliaries may be helpful, but usually the best remedy is to keep the beer in cellar for a few days, rolling the casks daily and adding a little sugar priming. After sometime the beer will take finings quite satisfactorily.

(7) Defective finings. Finings with a normal content of sulphurous acid are not liable to growth of bacteria or wild yeast, although these may survive in finings. A simple microscopic examination would show if finings were so grossly contaminated that they would be likely to affect the beer to which they were added. Mould may grow on finings left lying about in half empty containers, thereby giving a bad flavour to beer. The defect which is most likely to arise in summer is that finings may become warm, in which case they thin perceptibly and lose much of their fining power.

Clarification of beer by fining is a feature of present brewing practice and no substance acts so effectively as isinglass. Although the process is not subject to any simple scientific explanation it works with great regularity and precision in all normal beers.

All grades of isinglass work tolerably well, but there are small differences between isinglass from different sources which may be used to advantage to obtain the best results.

The variations in brewing materials and in gravities necessitated by war-time restrictions have had little effect on the process of fining and have only served to confirm the established practice.

In conclusion I desire to acknowledge the generous assistance I have received from Mr. Bernard Dixon in the preparation of this paper.

Anchor Brewery, Mile End Road. London, E.I.

An interesting discussion followed the reading of the paper.