Showing posts with label too technical stuff. Show all posts
Showing posts with label too technical stuff. Show all posts

Wednesday, 29 October 2008

Mashing 1850-1880

No more jokes for a while. Not until I travel again. It's back to book extracts, I'm afraid. Today we're taking a look at mashing.

Fascinating subject, mashing. There are so many different ways to mash. I've been really intrigued by some of the older methods, especially the 3 or 4 mash approach. If I were still brewing, I think I'd give one of those a try. Even though it's more work than just a single one-step infusion mash.

The material today comes from Frank Faulkner's "The Art of Brewing", published in 1876. It's a collection of essays originally published in the Brewers' Journal.

Reading Faulkner's theories has got me wondering about the old three-mash method and whether or not that acted in a similar way to a step mash. One method described by Loftus ("The Brewer", 1856) gave these striking heats:

1st mash 178º F
2nd mash 184º F
3rd mash 188º F

Though, of course, the first wort had already been drained off before the temperature was raised. However, some wort would have been absorbed by the grains and so would be heated during the second mash.

The mashing process and the theory behind it were evolving constantly during the 19th century. In 1800, London brewers mashed three times and sparged with relatively modest quantities of water. Picking up on techniques first employed in Scotland, by the middle of the 19th century, many were using a single mash and sparging with a much greater volume of water. Towards the end of the 1800's the simple step method, as described by Faulkner, where there was only one mash hot water was added part of the way through to raise the temperature, came into use.

There was more than one reason for the changes. Brewers were concerned with obtaining the best possible extract from their malt, but were also conscious of the need to speed up the process and to use as little energy as possible. Getting the desired proportion of different sugars in the wort - maltose and dextrin - later became equally important.

Faulkner's theories on mashing
During the mashing process, starch is converted to dextrine and then into sugar (maltose). By controlling the temperature and mashing time it was possible to control the proportion of dextrine and sugar (maltose) in the wort. How much dextrine was desirable, depended on the type of beer being brewed. Beers with a full palate, such as Stouts, and beers intended to be aged or exported, larger amounts of dextrine were benficial. Dextrine would not only add richness to the finished beer, but help to slow fermentation, something essential in a beer that would not be sold immediately. In beers intended to be fermented and sold quickly, relatively small amounts of dextrin were needed.

Worts with large amounts of detrine did not clear as easily nor ferment as readily.

Faulkner made specific mention of the difficulties of getting Stout right: "Much difficulty is experienced by many brewers in obtaining full tasted stouts, the error in the generality of processes being the excessive employment of saccharines; beyond this, the brown malt of a porter grist, besides having a different latent heat, has had its original strach so modified by the torrefication that it has undergone, that if ordinary heats are employed you are certain to procure from it a large proportion of actual sugar; and thus, from one cause or another, your stouts are highly saccharine and yet very deficient in palate fulness."

To get the required proportions of sugar (maltose) and dextrin, good quality malt, the right type of water and careful control of the mashing temperature were essential. Starch was converted into dextrin at one temperature and when the heat was increased dextrine was converted into sugar. By starting the mash at one temperature and then increasing it and leaving it to stand for a specific length of time, the conversion of dextrine into sugar could be controlled.

"You first of all use such a degree of heat as is capable of dissolving disatase, enabling it to convert starch into dextrine; and then you, by a simple addition of a further quantity of liquor at an increased temperature, enable the diastase to induce a further change - the conversion of dextrine into sugar."

Presumably this is why part of the way through the mash water hotter than that initially used was introduced via the underlet. This technique can be found in the logs of Whitbread and Fullers.

According to Faulkner, darker malts such as black and brown cooled mashing water less than paler malts and the same initial temperature could be obtained with a lower striking heat. A thicker mash required a higher striking heat (pretty obvious, as there was less water to heat the malt) and gave a less clear wort. A thin mash produced a clearer wort, but a worse extract.

This was Faulkner's preferred method of mashing when using an external Steel's masher:

"I am in favour of using two barrels of liquor per quarter when through a mixing machine at about 168º, which gives me an initial temperature of of 150º, rising to 156º or 158º before setting tap, and a tap gravity of 33º per barrel [og 1090º]. Now such a mash gives you, I believe, dextrine and sugar in equal proportions, with a satisfactory malt. If the malt is imperfectly malted, your dextrine is in greater proportion, since the diastase has had more work to effect, and you must adopt either some special kind of fermentation to allow of this dextrine being decomposed, or you may keep your wort for some time at a temperature of 170º after it runs from the mash tun, to allow of the diastase exerting its converting power on the excess of dextrine before the power of this converting agent is destroyed by the boiling temperature in the copper, or you may increase the proportion of sugar in your worts by the addition of saccharine."
As we'll see in the next chapter [this is book stuff, "next chapter" doesn't apply here] , "dextrine and sugar in equal proportions" is a bit wide of the mark. The ratio of maltose to dextrin was at best 3:1.

Faulkner's recommendation was somewhat different for breweries equipped with an internal rake masher:

"With rake machinery you mash in with about one and a-half-barrels per quarter at some 162º, and you allow this mixture to stand some thre-quarters of an hour; and then a secondary quantity of liquor, at a much higher temperature than the first, is forced under the false bottom and mixed in by the machinery. . . . If a dextrine beer is required - and I had better remark that it never is wanted in a small brewery - you take a sufficient quantity of second flow liquor at a rate of half a barrel per quarter to bring up the heat of the mash to 156º or 158º, while you stand some hour and a quarter after final mixing is finished, and then, on setting tap, bring the wort to the boil as soon as possible, to destroy the converting agent, and prevent the proportion of constituents being altered. . . .If, on the other hand, a saccharine beer is wanted, your second flow of liquor is taken at such a heat that the initial temperature is raised to 165º or 170º . . . . Time is another important feature. The longer you allow the mash to stand at this elevated temperature the more sugar you will obtain; but you must, on no account, stand so long as to allow cooling down taking place."

With the "saccharine beer" method, it was important to ensure all the starch had been converted before applying the higher temperature water, otherwise starch might end up in the wort. Iodine was used to test the wort for starch as it was run off. If it were present, the wort was kept at 170º for an hour in the copper before being boiled.

Faulkner recommended sparging in the same way, no matter which type of mash had been employed. The sparging water needed to be warm enough to convert any remaining dextrine in the cooler upper portion of the mash to maltose, but not so hot as to dissolve unconverted starch nor destroy the diastase. If the temperature fell too low, lactic acid was likely to form. To satisfy all these considerations, 176º F was the perfect temperature.