I know. I'm a butterfly. Today we've jumped back in time to the early 19th century. A period from which brewing records still exist.
This period saw a key change in British brewing practices. Though brewers had already been aware of the better yield of pale malt compared to brown, it was only with the introduction of the hydrometer that this could be quantified. It became apparent that, despite the lower price of brown malt, it was still cheaper to brew from pale malt. Brown malt produced only about two thirds as much fermentable material as pale.
Up until this time a variety of base malts had been used. Usually only one malt was used and it was a major determinant of style. Porter began as a Brown Beer, brewed from 100% brown malt.
When the malt tax was increased to help pay for the Napoleonic War, brewers had an incentive to use less malt. Their solution was to use a proportion of pale malt in everything, including dark beers. By 1800, Porter grists contained more pale than brown malt. Eventually, pale malt was the only base malt used.
This is the first period for which brewing logs still survive. Which means that a lot more detailed information is available about exactly how Porter was brewed and which malts were used.
Here are some examples from a couple of the big London breweries.
You have to wonder how dark the Whitbread Porter was, with such a large percentage of pale malt. Barclay Perkins were still in a period of transition, as can be seen by the fall in brown malt content between 1805 and 1812.
Whereas the original Porters all had the same malt bill (100% brown malt), the move to pale malt led to much more diverse grists. Various combinations of pal, amber and brown malt were used by different breweries. In the examples above, this divergence is already noticeable. Barclay Perkins Porter, with more than double the proportion of brown malt, muct have tasted quite different to Whitbread's. As the 19th century progressed, Porter recipes from different breweries grew even further apart.
Barclay Perkins were still making a Pale Stout in 1805 but by 1812 it had been phased out. It was a throwback to the early 18th century where "Stout" could be used to describe any strong Beer or Ale. Pale Stout was just a strong Beer brewed from pale malt.
To compensate for the reduced brown malt content, various methods were tried to colour Porter. One of the simplest was an addition of caramel. This was not always legal as the use of sugar was only sporadically permitted, usually when there was a malt shortage. Some breweries boiled down wort to produce a concentrate. Being derived from malt, this was always legal but wasn't wonderfully convenient. This problem was finally solved just after the period addressed by this chapter: with Wheeler's invention of patent malt in 1817.
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