The heart of our brewery: a 7HL lactic acid tank

After 18 months of planning, staring at spreadsheets and pacing the halls, our new brewhouse is installed and is ready for commissioning – what a relief at last!

When we dreamt up Lost and Grounded Brewers, we knew we wanted something special about how we made beer to drive our attention to detail.  In the past I worked in a brewery that bottle conditioned large volumes of pale ale, and that drove our attention to detail and from that time I always felt that a brewery works best if they know what makes them unique.  As previously stated, we haven’t established the brewery to recreate our past efforts, and knew for sure we wanted to test ourselves technically so that we are continually learning.  After considering many things, we finally decided on one process that would define us:

The use of biological acidification in the brewhouse.

“Biological acidification” is a traditional German technique that is rarely seen outside of their borders, and can help naturally deal with alkaline brewing water, such as the water we have in Bristol.  In this system biological (lactic) acid is naturally and continually propagated in a dedicated tank in the brewhouse and is used to adjust the pH during brewing.  In addition to the benefit of helping combat alkaline water, wort produced with biological acidification is thought to result in beer with a well-rounded, fuller bodied and softer palate,  a clean hop character and a more stable foam.  We are really excited to see not only how this will impact on all the beers we produce, be it our lagers or Belgian-influenced ales.

In a simple one-tank system, such as what we have a Lost and Grounded Brewers, the tank is filled with the first runnings from the lauter tun and is inoculated with a special strain of lactic acid bacteria.  The contents of the tank is held at ca. 48degC in an anaerobic environment to allow the bacteria to get on with its job – producing lactic acid; over several days the lactic acid content climbs to ca. 1.5%.  Once a stable propagation is established we will dose this acid every brew, and in turn top up the tank from the following brew, in an almost continuous process.  The strain of lactic acid bacteria used is important, in our case lactobacillus amylovorus, in that it has originally been isolated from the husk of malt, and is extremely sensitive to iso-alpha acids – so much so that it won’t survive in beer with >10 IBU (this is important as it cannot infect our beer downstream, and hence why unhopped wort must be used for the propagation).

Control of temperature will be critical to the production of lactic acid.

Control of pH is critical in brewing to ensure quality of the wort and finished beer, with pH being one critical parameter that will strongly influence the finish and palate of the beer.  Swings of pH by merely 0.3 units high can give beer a much heavier mouthfeel, whereas if it swings low the beer can seem thin.  Whilst pH is certainly not the only parameter that influences the palate, we feel it is one that we feel gets often overlooked and must be carefully considered along with final gravity, CO2 content, protein content of the malt, etc.

The use of this natural acid has many advantages, but philosophically there is one: the acid is produced naturally, and is close to the final beer “milieu” or environment as it has been produced from the wort itself.  Acidification techniques vary from brewery to brewery, with some adjusting pH only by the addition of calcium (calcium sulphate “gypsum” or calcium chloride), by the addition of technical acids, e.g. phosphoric acid, sulphuric acid or lactic acid (produced from sugar), or a combination of methods (calcium plus acid).  As the water in Bristol is fairly alkaline, we will most likely also use a combination of methods, namely addition of calcium to the mash and biological acid to the wort kettle.

For those who have a keen interest in science and pH in brewing, here is a great article written by Tim O’Rourke in 2002, published by the Institute of Brewing and Distilling (IBD)  and another one by Charles Bamforth for a Master Brewers Association of the Americas (MBAA) meeting.

Anyway, we are off to re-read the section in Kunze Technology Brewing and Malting on biological acidification!  (*Gulps*, no pressure!)

Cheers!

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