Saturday, 22 October 2011

Scottish fermentation in the 1850's

Time for some more extracts from William Stewart's rambling account to Scottish brewing practices. They must have been paying him by the word. He must have had the powers of concentration of a goldfish, judging by the way he jumps backwards and forwards between subjects. He could done with an editor.

"The degree of heat of the worts at which the yeast store is added, is of the utmost importance, as it regulates the time of the process of fermentation.

In the Scottish system of brewing, it ranges from 50° to 55°, according to the season of the year, or, more particularly, according to the existing state of the atmosphere. In the English system of quick fermentation, the range of heat is from 60° to 65°; in both cases being the best that can possibly be used for carrying through the respective processes, and obtaining the desired combination of alcohol and solution of starch-sugar to constitute strong ale."
"Brewing and distillation. With practical instructions for brewing porter and ales according to the English and Scottish methods by William Stewart" by Thomas Thomson and William Stewart, 1859, page 218.

Remember those temperatures for later. I'll be giving a test. No, we'll be looking at an example from the same period.

But first, some more from William Stewart:
"After the worts are pitched, and the yeast has struck, for the first ten or twelve hours a decided alteration takes place, and they are turbid and unsettled in appearance; and a scum of a greyish colour has gathered on the surface. In twelve hours more a white circle, narrow and regular, appears round the edge of the gyle, the surface begins to chip, and shew irregular patches of white breaking through; then these unite and shoot up in little pyramids,—a proof that the yeast is beginning to form on the surface, and that carbonic acid is escaping from the worts. This is the first stage of the fermentation, which the brewer looks upon as an assurance that his gyle is in a healthy state. The whole head of the worts is now covered with froth, which the brewer watches, and, as soon as he judges that the yeast is sufficiently formed, the head on the surface of the worts is beat down, and the process of fermentation allowed to go on for twenty-four hours.

At this part of the process, the Alloa district brewers have a method of quickening the fermentation, which is very serviceable. They prepare a half-fermented wort, which is termed fillings. Reserving half a hogshead from the coolers, they put this to quick fermentation at 62°, and by the second day of the gyle's age these fillings are ready. They throw into the gyle ten or twelve Scotch pints,— about five gallons English measure,—the effect of which is to make the fermentation lively and healthful. These fillings serve another purpose, for which they are chiefly intended. By the Alloa method of fermentation, the contents of the gyle, when finished,. are cleansed or run into butts, from which the ale is racked into casks as required, and the fillings are added, to preserve its keeping quality. This method, however, is incidental, as their chief markets for consumpt are too distant to admit of their following the Edinburgh mode of cleansing into barrels at once, and sending out to customers. The Alloa ale, from this cause, is liable to become a little hard. In my opinion, when judiciously ordered by the customer, and used in time, it is all the better for this. the Edinburgh ale being sometimes complained of as being rather soft; but this is no fault of the brewers, —their customers cannot endure the least taste of the bitter principle of hops. The Edinburgh trade, therefore, use particular care to extract the aroma, without permitting the bitter to be much infused, except in their summer keeping ale. When ale is exposed to heat, either in a warm apartment, or by a change from very cold to mild weather, the aroma of the hops held in it escapes, and, not having sufficient bitter for support, sometimes acquires a soft, weak taste. But brewers must study the public demand; and such occasional condition, even of the best kind, cannot be avoided."
"Brewing and distillation. With practical instructions for brewing porter and ales according to the English and Scottish methods by William Stewart" by Thomas Thomson and William Stewart, 1859, pages 220 - 222.
As soon as the yeast has formed a head, give the bastard a good beating. We've already learned that beating was intended to rouse the yeast and encourage fermentation. A bit like in a Yorkshire square. In Alloa they also added "fillings" (this has been mentioned a couple of times already) to speed up fermentation. You have to wonder why they didn't just let the wort warm up more is they wanted to hurry things up.

Handy things these fillings. Used to boost primary fermentation and to prime casks. How long did this practice continue? Did they switch to sugar primings later in the 19th century? I keep finding more questions.

As we'll see later, by the 1850's it was no longer totally true that Edinburgh brewers didn't ever cleanse in separate vessels.

There's another mention of Edinburgh brewers aiming for hop aroma rather than bitterness. It's certsainly true that William Younger went in for short boils in the first half of the 19th century. But that changed in the 1850's. During the course of the decade their boil times increased from an average of 60 to 70 minutes to between 90 and 105 minutes. The hopping rates of their weaker Shilling Ales increased, too. There will be loads more details of Younger's boiling and hopping in a future post. (When I've collected all the data.) Was the taste of Edinburgh punters changing or was more beer being sent elsewhere?

"There cannot be any rule established for beating in the yeast, sometimes it is requisite twice in one day, sometimes not for two days together; neither can time be fixed on to determine the duration of the process of fermentation. Much depends on the quality and quantity of yeast employed to commence the process, and the heat of the worts when set to ferment."
"Brewing and distillation. With practical instructions for brewing porter and ales according to the English and Scottish methods by William Stewart" by Thomas Thomson and William Stewart, 1859, page 223.

Beating down worts was popular in Scotland. William Younger certainly went in for it. I know. Let's have a look at some of their beats:

The large number in the "Heats and Beats" column is the wort temperature. The small number underneath the number of beats. The columns numbered 1 to 9 are the days after the start of fermentation. You can see that there was no beating until day 2 and little or no beating on the last day. Note that all the worts were pitched at 57º F - 2 degrees higher than the top of the range given by Stewart.

"To return to the process of fermentation of the brewing. Twenty-four hours after the head of yeast has been beat in the renewed yeast comes thicker to the surface of the worts, of a light cream-colour, and of a firmer appearance. The progress of the heat and attenuation, or resolution of the starch-sugar into alcohol, must be carefully ascertained. The increase of heat altogether, to the finishing of the ale, must not exceed 10° or 11°; but the attenuation required, being according to the future views of the brewer, cannot be fixed by any arbitrary rule. In the present case, 94 lbs. saccharine extract is the strength of the wort, and the attenuation required is, that it shall be carried down to 45 lbs. per barrel. The duration of the process, therefore, depends on regulating the heat until the attenuation is accomplished. The heat should advance progressively, and is either kept in check or encouraged by the use of the tube, which is fixed round the inside of the gyle, taking five or six turns from top to bottom, through which hot or cold water can be run at the pleasure of the brewer. In eight days the heat has increased 10º, and the attenuation, as indicated by the saccharometer, is down to 50 lbs. per barrel, the head of yeast on the worts having been plunged occasionally during that time.
"Brewing and distillation. With practical instructions for brewing porter and ales according to the English and Scottish methods by William Stewart" by Thomas Thomson and William Stewart, 1859, pages 222 - 223.

You can see from the Younger's record above that they let the temperature of some worts rise more than 11º F. In some cases it was as much as 16º F. Like boiling times, the pitching temperatures at William Younger increased as the 19th century progressed.  More about that later.

I've no idea what scale is being used for gravity measurements. Not that it matter much for the purposes of attenuation. I make 94 to 45 52.1% attenuation. Doesn't sound like much, but that's how the Scots liked their beers: thick and treacly. In the 1840's, Younger's Shilling Ales had between 50 and 60% apparent attenuation. By 1858 this had increased to 59 to 64%.

That tube he describes has a name: an attemperator. Don't know why he didn't call it that.

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