Saturday, 26 January 2013

Inside the Dorchester Brewery (part two)

This time we'll be looking at that most crucial brewing operation: mashing. And the bits of equipment needed to carry it out. It's going to be fun. If reading a long technical description is your idea of fun. It is mine, but I suspect I'm not 100% typical of the human race.

I'm very disappointed in Barnard. There are no illustrations of either the mash tuns or coppers at Eldridge Pope. You'll have to use your imaginations. I lost mine years ago. I now rely on occasionally borrowing my son Alexei's. He's more than enough for two.

Come to think of it, Barnard doesn't seem to have spent a great deal of his visit to Dorchester inside the brewery. His Eldridge Pope sandwich is sadly lacking in meat. The first chapter is mostly general bullshit about Dorchester, literary quotations and a visit to Mr. Pope's country house. Maybe by the third volume he was getting fed up of hanging around in brew houses.

"Leaving the mill room behind us, we came to the sub-floor of the mashing stage, where is fixed the shafting that drives the grains conveyor, and the safes for setting taps, through which the wort runs to underback.

After this we ascended half-a-dozen steps to the noble mashing stage, open to the roof, and lighted by a dozen windows. Six of them are very lofty ; the others are smaller. Along one side there is a handsome gallery, reached by two staircases, which gives access to the hop rooms, cooling chamber, and the liquor-backs. On this spacious floor stand two cast-iron mash tuns—splendid vessels, each lagged with felt, and encased in pine-wood staves. Both have covers, lifted up and down by compensating weights ; also perforated iron draining plates; and their mashing capacity is twenty-four and forty-five quarters respectively. Each tun is commanded by a Steel's mashing machine, fed from the grist-case above, and has a three-armed sparger for sprinkling the goods. The grains are discharged from the tuns by an endless chain-belt, fitted into a cylinder, which conveys them to an iron tank, erected on massive columns, in the east courtyard.  From thence, when required, they are passed through an automatic busheller, or measurer, into the railway trucks or farmers' carts. By the side of each tun there is a standard valve, to enable the brewer to work the underlets from this stage; and outside each vessel is a thermometer, to mark the temperature of its contents.
"Noted Breweries of Great Britain and Ireland, vol III", by Alfred Barnard, 1890, pages 132 - 133.
I can't fault his description of the mash tuns. Nicely insulated, cast-iron tuns with lids. I can picture them exactly. The Steel's masher must important innovations in brewing equipment of all time. It's still a standard piece of kit in British breweries.

As I've seen some of Eldridge Pope's brewing records from just a handful of years after Barnrds's visit, I've some idea of how they were used. Most of the beers seems to have been mashed in the large mash tun. With a charge of 30-odd 60 quarters of malt. Larger batches, of 47 to 60 quarters, used both mash tuns.

Only the Double Stout and LTS were mashed solely in the smaller tun. There the charge was only 11 quarters. Its indicative of a relatively small demand for these beers that they were brewed in batches of just 50 to 60 barrels. The brew lengths of Mild and Pale Ale were much greater, 200 to 250 barrels, though usually not of one single beer. Mostly two or three were parti-gyled together.

Barnard makes a big deal of having got up early for the first mash of the day. Perhpas that's why his illustrator didn't tag along.
"Yesterday we followed the malt to the hopper, or twin grist-case, where it rests until required for mashing ; to-day we pursued its course therefrom until it became the ale of commerce. Here, let us add, early as was the hour, some of the men, whose duty it is to heat the mashing liquor, had already been at work a long time before we put in our appearance.

The mashing operation commenced immediately we appeared on the scene, and was performed, in the first instance, by passing the ground malt and water through the Steel's masher, referred to in the previous chapter, whereby the malt is saturated at a mixing heat of 150º or thereabouts, according to the lightness or heaviness of the beer required to be brewed. The general proportions are about one-and-a-half to two barrels of water to a quarter of malt, finishing with a little more water of a higher temperature.

From the Steel's mashing machine the mixture, in its saturated condition, falls into the mash tun, when the revolving rakes are set going until the goods rise to the proper heats, the object of the operator being to prevent coagulation, or setting of the "goods;" hence the rakes are kept going until the goods are seen to touch the line of saccharification.

With good water, good malt, and proper mash heats, good beer should follow as a matter of course. We did not wait to see the conclusion of the operation, which lasts from five to six hours, but our guide informed us that the draining of the wort from the goods (or grain) takes place about two hours after the mashing operations are completed.

The draining is accomplished slowly at first, by several cocks, placed in the bottom of the mash tun, and the wort is carried to the coppers, through main pipes constructed of copper and lined with tin."
"Noted Breweries of Great Britain and Ireland, vol III", by Alfred Barnard, 1890, Page 136.

Barnard is about right with the mashing temperature. The tap heats were between 150º F and 154º F. But he's wrong about the water to malt ratio. It was over two barrels to a quarter of malt. As this table shows:

quarters malt barrels water (initial) barrels water (second) barrels water to a quarter malt (just initial) barrels water to a quarter malt
AK 39 85 5 2.18 2.31
BAK and AK 34 74 5 2.18 2.32
PA and XX 32 72 5 2.25 2.41
S 11 23 3 2.09 2.36
LTS 11 20 4 1.82 2.18
XX and XXX 47 103 8 2.19 2.36
XXXX 60 129 9 2.15 2.30
KK and XX 30 66 5 2.20 2.37
Eldridge Pope brewing records

The second dose of a small quantity of hotter water reminds me of the underlet mashing method London brewers loved. That's where 20-30 minutes after the initial infusion a small amount of hotter water was added via the underlet. It's a very simple type of step mash. The second addition followed more quickly at Eldridge Pope after just 5 to 15 minutes.

It's interesting that they kept the internal rakes revolving until the mash hit saccharification temperature. When using a Steel's masher, you don't normally need to do that. The grain and hot water are already mixed as they enter the tun. Breweries did keep their internal rakes, but only used them in specific circumstances, such as after an underlet or when a mash threatened to get "stuck".

I hope this hasn't been too technical for you. There will be more of the same next time. That's a thromise.


Barm said...

Today brewers heat the water overnight for the first mash of the day, by electricity on a timer. When they burned coal to do it, leaving it unattended can’t have been very safe. Perhaps that’s one of the reasons breweries used to go on fire so often. said...

The Dorchester Eagles Midget football team ages (13-15) from Dorchester Mass got into a fight at the food courts with another team from Edgewood, Rhode Island. Supposedly the players from one team were taunting the other team about losing it's initial game.

Driving Instructor Dorchester