Tuesday, 23 February 2010

Porter malt (1849)

Continuing on my Porter theme (don't be surprised if you'd not noticed I had one), something about  porter malt.

I think they mean brown malt. That's certainly what it sounds like. Note that the method - finishing kilning very quickly and at a very high temperature - cannot be the same as that practised in the 18th century as all the diastase was destroyed. Whereas in the 1700's brown malt was a base malt, often used by itself.

"As porter is made by provincial brewers in the same utensils as those in which they make their ales, it is unnecessary either to repeat a description of them or to notice their dimensions ; but it may not be unacceptable to the reader to notice the method of making porter-malt; as every brewer should have some knowledge of the mode of preparing it,—although it has been nearly displaced, in large establishments, by the more profitable use of pale malt in porter-brewing.

The form of the genuine porter malt-kiln differs from the common description for drying pale malt. The floor of the former is laid with tiles in the usual manner where such are used. The fire-chamber beneath is built with brick, within the square apartment, in the shape of an inverted pyramid, in the apex of which the furnace is placed. The furnace is arched with fireibrick, and extends 2.5 feet within the chamber, to disperse the heat equally to the floor above.

The malt to be prepared for porter-brewing is half made in the usual manner for drying pale malt. It is then divided into two or three parts, which are dried and finished on the kiln at such a high temperature as speedily turns it of a brown-colour, but without scorching or charring it; and converts it into porter malt.

It is first dried with coke in the usual manner. Birch-cuttings, or beech, when the former cannot be procured, are prepared to blow it, as it is termed, on the kiln, and give it the brown colour and that bitter principle which is so desirable to the taste in the consumption of porter.

When the malt is spread on the kiln-floor, the furnace is gradually charged with the wood-cuttings until a temperature upwards of 200° is obtained. It is carefully watched by the maltster, until it begins to burst by the escape of the air confined between the kernel and husk of the grain. It is now turned by the maltster and his assistants with shovel and broom, working it quickly, and sweeping each division, as it is proceeded with; and this process is repeated until it is judged sufficiently brown for its purpose.

By this incipient charring its germinating principle is destroyed, and it loses the capacity of yielding sugar, by mashing, in the proportion of twenty per cent to pale malt made from the same description of barley."
"Brewing and Distillation" by Thomas Thomson and William Stewart, 1849, pages 278-279.

Now all I need is an 18th-century account with a similar level of detail.


Gary Gillman said...

Ron, in this 1700's discussion going on for some pages (see below), the distinction between high-dried brown malt and blown malt is clearly drawn. The author clearly considers that either malt will produce beer, but notes that blown has a tendency to set the grist as he puts it (not solubilize). As I read this account, brown (not blown) malt was simply pale malt allowed to dry at the same degree of heat as for the latter, but just longer.

Blown malt was different, you raised the heat significantly on pale malt and quick-dried it. The 1800's books seem to treat mostly of the blown type. Since brewers by then were using pale malt in the mash, the difficulties of solubility or lack of diastase were less significant.

How did 1700's overcome these problems with a 100% brown malt mash, regular or blown? I think they must have mashed for longer, or had tricks to ensure the extract that the brown or blown did contain could be utilized. It is well to recall even ground raw grains can be mashed - 100% raw, no malt. It just takes longer and with less certain results. Malting really is a kind of short-cut, a process improvement on what nature will do.

Porter brewers must have had ways to make their low or no-diastase mashes work in the 1700's, either time or other techniques must have assisted. Perhaps they always added some pale malt even though not recorded, maybe that was one of the tricks of the trade not mentioned in the books. I should look again though at the 1763 Hertfordshire brewer's brown stout method, was his mashing longer than is usual today?



Gary Gillman said...

This may be crazy but remember that discussion about pilsner malt in an Imperial stout grist at Courage? Jackson wrote about it in the 1980's, as did Roger Protz I believe. Maybe some pale malt was always added to brown malt mashes in London to assist conversion. (The diastase in the pale malt would convert the starches in the rest, just as it does when grain adjuncts are added). Maybe this was a trade secret in London.

Once pale malt became generalized in porter mashes in the 1800's, the memory of the need to add something "special" may have prompted addition of another pale-coloured malt, lager malt, and the practice continued long after people forgot why.

Stranger things have happened. I would point out too that small amounts of barley malt have great ability to convert non-diastase-carrying starches in the mash. American rye whiskey in the 1800's was often made from 80% unmalted rye and 20% barley malt or rye malt. In fact, sometimes only 10% malt was used. Those whiskeys were drank in American saloon bars. The saloon bar of the 1800's in America though was more like the public bar in England, somehow the term got changed around here.


Ron Pattinson said...

Gary, a bit of pale malt isn't going to contain enough diastase to convert a whole load of brown malt. And why don't any recipes mention adding pale malt. Like the 18th century recipes I published recently. And Brown malt was in use before pale malt existed.

Brown malt must have been diastatic.

Gary Gillman said...

10% barley malt will convert 90% raw grains as I said.

I am not sure brown malt came before pale, Ron, I rather think it was the reverse, if only that it takes longer to make brown malt than pale.

True, the recipes don't mention it. But maybe it was trade secret.


Graham Wheeler said...

I read that last sentence to mean 20% down; having 80% of the extract of pale malt. That is liveable with.

Gary Gillman said...

I think Graham you once stated that it might make a difference whether the brown malts were prepared when the pale malt was still moist. In reading up on various current malts, it appears the Vienna type, and others similar, are stewed as it's called, retaining such moisture. These are indicated often as diastatic. Roasted malts, so-termed, are indicated as non-diastatic. Maybe the 1700's brown malts were prepared when the pale malt was damp and later, when their extract was less important, that feature disappeared.


Graham Wheeler said...

Gary, I guess that if you took a kernel of old-time brown or amber and cut it in half, only the outside of the grain will be coloured. The inside will still be pale-ish. The 20% loss is probably the 20% of the outside that is charred, and it is only the outside that provides the colour.

The moisture prevents the inside of the grain reaching the same temperature as the outside and therefore it does not acquire the same colour.

The moisture in the grain causes the malt to swell when the high heat is applied - become blown. This also has implications on extract if malt is measured by the volumetric bushel, because the grain is bigger.

Modern-style malts were dried completely by gradually increasing temperature over a matter of days. The final temperature does the colouring, and, because it is dry it colours the malt all way through. This way a lower final temperature is required to achieve more colour and the extract and enzymes are better preserved.

Old-time brown malt was nowhere near as highly coloured as modern brown malt. Modern brown malt is coloured all way through at a fairly high temperature and its enzymes get destroyed. Modern brown is 150EBC, Old-time brown could not have been any darker than about 40 or 50EBC, probably less.

The malt would have to have been got off the kiln pretty smartish once it turned the right colour.

The product must have been highly variable.

Graham Wheeler said...

As an addendum, I will point out that brown malt and porter malt might not be the same thing in all cases.

It seems quite likely that there was a class of malt that was even more highly charred than standard brown malt. Terminology gets confusing and intertwined, and the references I have on malting are not extensive, malting usually being mentioned as part of a more comprehensive book and not at all authoritatively.

There seems to be a narrow window from the late 1700s to the beginning of the 1800s where porter malt is mentioned explicitly.

My guess is that as pale malt was replacing brown and amber malt, there were attempts to maintain colour and flavour by charring the remaining portion of brown malt more highly.

It seems to have been very short-lived. Perhaps too many malthouses were burning down.

Indeed, one of the Google books references I looked at, can't remember which one, but probably one that Gary pointed out, gives a table of relative extracts. In that table, porter malt and brown malt have separate entries, from what I remember.

Might be that blown malt and brown malt had separate entries, but there was a distinction along those lines.

Trouble is that terminology is inconsistent and probably regional too.

Ron Pattinson said...

Graham, I won't argue about the terminology being confusing.

I suspect you're right about brown malt becoming darker in the late 18th century. Otherwise how could you brew a Porter of the right colour with just 35% brown and 65% pale malt?

Gary Gillman said...

Makes a lot of sense, but note this from 1735 (London's beer is "black as bull's blood")!