Double dropping

Double dropping, more commonly known as the dropping system is a brewing method for the production of ales. During the early 20th century it was the most popular method of fermentation for English ales. It is less commonly used today as it requires additional brewing vessels and a 2-tier brewhouse. Also, other brewing methods can now emulate these beers without using this brewing method.

During the double dropping process the wort (newly brewed, fermenting beer) is first fermented for a period of time before being 'dropped', under gravity or by other means, into a lower vessel where it continues fermentation. Brakspear's beers are 'dropped' the morning after the day they were brewed - typically about 16 hours later. This process originally took place at the original Brakspear's brewhouse in Henley. Some time later, Brakspear's brewing then moved to Refresh UK's brewery in Whitney. A new Brakspears brewhouse was built to include the original double dropping system.

The dropping process has two primary effects on the beer being fermented. In 'dropping' the newly fermenting beer, 'trub' (dead yeast and excess, staling and haze-forming protein from the malted barley) that has settled during the first period of fermentation will be left behind, leaving a cleaner beer and a cleaner yeast to crop from the beer for the next fermentation.

The second effect of the dropping process is the aeration of the wort, which results in healthy clean yeast growth, and in certain circumstances produces more complex flavors. Brakspear attributes that some of the flavor common to its beers is due to a combination of its very old complex multi-strain yeast and the dropping method which encourages it to produce the butterscotch-flavored compound diacetyl.

Breweries using the double dropping process

• Brakspear - uses double dropping for all its regular beers
• Marston's - uses double dropping for some of its beers