Mitchells & Butlers. Brewing School visits 1968 to 1969
Mitchells & Butlers Ltd, Cape Hill Brewery, Smethwick
Visit by Brewing School students – October 1968
The company occupies a 90 acre site at Smethwick in Birmingham. There are three breweries on site. Number one built in 1878, number two in 1914 with the number three, a German block brewhouse of 1959. There are various extensions added at times when expansion demanded. There is a large transport department and various administration divisions of the Bass Charrington group. In all well over 2,000 people are employed on the site. Mitchells and Butlers started brewing in 1866 at sites elsewhere. Today number one brewery is concerned in most of the fermentation as well as conditioning and racking while number two is a brewhouse with some fermentation and storage space. No 3 produces hot wort on a block principle for fermentation in No 1. Our visit did not include the No 1 brewery where the four mash tuns and seven coppers are gradually being superseded. The old maltings attached are in the process of being fitted out with redox tanks. Our visit extended over No 2 and No 3 with a brief visit to the bottling stores
Malt
Even though at one time barley was grown and malted on the site; today malt arrives from commercial maltsters in bulk wagons. Two 100 quarter lorries may unload into hoppers at one time. During the unloading, which takes half an hour, the malt is elevated and put into bins. 12 x 1,000 quarter bins of 1920 vintage have wooden sides and metal bases which are fed from conveyors via flexible hoses. There are some new bins set completely in concrete comprising six x 500 quarters, 4 x 250 quarters and 10 x 100 quarters with two 60 quarter bins for black malt. This malt store once fully charged would last for one to two months.
Crystal and chocolate malt is kept in sack in the space between the conical bottoms of the old bins. Wheat flour is held in small bins outside. The malt control room has a flow diagram attached to the panel so that the blending process may be readily monitored. The total number of quarters required is set and the percentage of malt wanted from each of the various bins is set on a dial referring to that bin. The blending process which is fully automatic then takes that percentage of one quarter from the appropriate bin and deposits that one quarter fully blended into a weigher.
The process continues until all the malt for that mash is weighed. The malt is then completely mixed which when wheat flour is used can be significant in preventing a set mash. The blending continues at a rate of one quarter per minute. Black malt has a separate hopper but is still integrated into the overall malt system. The intake of malt from wagons is not fully automated, the slides being hand operated but position of those slides is indicated on the panel. The malt bins are from time to time gassed with sulphur dioxide although malt infestation is less of a problem these days. The weighed malt is drawn by suction to the top of the next block for milling.
Hops
Day to day hops are brought out of the cold store and kept in the space above the old malt bins. The usual English hops are used with quantities of British Columbia and Belgian hops. The hops are weighed into individual bags with a colour code to show their copper destination.
Milling
No 2 Brewery has a Seck mill and No 3 a Boby. The Seck mill yields a grist of much rough appearance has it is bound for mash tuns.
Liquor
Brewery water (with some degree of natural hardness) comes from six wells on the site at a temperature of 50oF all year round. A hardening plant adds calcium sulphate. There are three 330 barrel cold liquor tanks and six hot liquor tanks of 200 barrel capacity (four in No 2 Brewery). For mild ale the standard liquor is treated with more chloride.
Mashing
The equipment in No 2 brewery is geared to a maximum mash of 72 quarters. There are three flat top mash tuns with two Steels mashers in between them. Opposite the tuns and on a lower stage are three pressure coppers. Although the system is interlinked, in general each tun empties into the copper opposite. The run off is controlled manually and with up to 10% wheat flour, care is needed to prevent the mash settling on to the plates. Grains are mechanically emptied into a Ponndorf compressed air system for disposal.
Coppers
The coppers at 280 barrow capacity operate at a pressure of 2 psi. Except for pale ale, all the hops are added at filling. With Brew XI getting some flavour added before casting. Since the coppers were originally coal fired, then oil, the base is convex which is less efficient for steam heating today. No Irish Moss is added to help coagulate the break. Bulk sugar added to the copper is kept in a hot sugar room in tanks. The room temperature is 130°F. Two 280 barrel hop backs with flat bottoms are used. Usually, one back takes two mild ale brews and the other the bitter brew. But when three mild brews are performed, they all go through the one hot back. The wort is recirculated until it appears bright. Spent hops are slurried and squeezed at the hopper and the used liquor returned for more slurrying.
Block brewhouse
The German block was built by Ziemann in 1959 in an existing building. From the main line, malt is milled by a Boby mill and dropped into a grist case. There are two hot liquor tanks, one for brewing and one for sparge and cleaning. The rest of the system is situated behind the screen in a large room. A horizontal cylindrical lauter tun above with a copper and mash mixer below. The hop back is at a lower level still. The other wall has control boxes with elaborate safety provisions and there is a panel to control the process. 46 quarter is the maximum brew and a mash takes place every four hours that is 100 barrels of Mild Ale per hour.
The mash stands for one and a half hours at 150°F with the motor mixer running and is then transferred above by means of a strong slurry pump to the lauter tun. Cutters keep the bed of grain open so that rapid runoff is possible. Flaps are adjusted on the cutters to provide a solid face for pushing the grains down to an end channel where they are screwed away to the Ponndorf arrangement.
A 250 barrel copper is in the form of a horizontal cylinder of similar dimensions as the mash mixer. The copper has a steam jacket along the bottom and up one side which imparts a rolling motion to the wort. In order to get one brew every four instead of five hours the mash mixer is used as an underback. So it is fitted with a steam heater. When the copper is emptied of the last boil it can be immediately refilled which a new batch of almost boiling wort. This heater in the masher was also useful when lager was made in the plant. The process uses a large underlet and reduced sparge only two barrels per quarter, the 16 taps controlling runoff from the lauter tun maybe individually worked or automatically linked by setting levers and turning a separate wheel. Any beer may be produced in this brewhouse. There is a conical hopback with tangential jets falls slurrying.
The wort then goes to No 1 Brewery for cooling and fermentation. All No 3 wort go to No 1 Brewery with one mash tun from No 2. The No 2 fermentation section deals with the rest of the output of No 2 Brewery. In No 2 fermentation block there are two wort receivers and 3 x 90 barrel per hour paraflows of which two are used at a time. The 50°F well water is fed and the hot water used later for cask washing.
There is a yeast culture room where 40 barrels of strong work is sterilised and transferred to two stainless steel tanks. Each tank can produce yeast for 200 barrels of wort in 48 hours.
For fermentation each brew is collected in four collecting vessels of which there are 14 in total. These hold 250 barrels to the top. There is no partigyling. The dip is taken and yeast pitched.
After 24 hours the fermenting wort is dropped to FVs below where there are 48 smaller vessels. The wort is aerated and much trub is left behind. There is parachute skimming into the chute of the skimmer on the FV below. Yeast is collected in slate vessels and it is pitched as such or pressed for Marmite. The No 1 Brewery fermentation process involves suction skimming. They are experimenting with centrifuges to obtain controllable yeast counts.
Beer is dropped to racking tanks the day before racking. The racking room is for both breweries and has a selection of 220 and 110 barrel tanks of steel structure with epoxy resin lining. Racking is semi-automatics; six casks being filled in one operation and then simultaneously removed from the stage. There is no dry hopping. Of an average output of 25,000 barrels per week about three quarters is in cask.
No kegging is done at Cape Hill. Today few road tankers are filled either.
In the bottling stores, from intake crates are depalletised by machine and bottles are automatically removed from crates for washing. Pasteurisation is in bottle. The crates are then palletised by machine ready for dispatch.