Porter (beer)

Porter is a style of beer that was developed in London in the early 18th century. It is well-hopped and dark in appearance owing to the use of brown malt. The name is believed to have originated from its popularity with porters.

Porter became the first beer style brewed around the world, being produced in Ireland, North America, Sweden, and Russia by the end of the 18th century.

The history of stout and porter are intertwined. The name "stout", used for a dark beer, came about because strong porters were marketed as "stout porter", later being shortened to just stout. Guinness Extra Stout was originally called "Extra Superior Porter" and was not given the name "Extra Stout" until 1840. Today, the terms stout and porter are used by different breweries almost interchangeably to describe dark beers, and have more in common than in distinction.

Porter was first mentioned in 1721, as a development of the brown beer already being produced across London, and delivered to publicans to age and blend to their customers' tastes; the term had become common in print by the 1760s, but was often not used by the brewers themselves before then. The innovation is attributed to Ralph Harwood, a brewer at the Bell Brewhouse in Shoreditch. The first delivery of porter was claimed to be to the Blue Last pub in Shoreditch.

Before 1700, London brewers sent out their beer very young, as "Milds"; any ageing into "Stale" styles was either performed by the publican or a dealer, with blends of Milds and Stales often sold to the public. Porter was one of the first beer styles to be aged at the brewery and dispatched in a condition fit to be drunk immediately. It was also a style that could be made on a large scale, and the London porter brewers, such as Whitbread, Truman, Parsons, and Thrale, achieved economies of scale, and financial success.

According to Martyn Cornell, "London-brewed Porter was the first beer to be widely exported, reaching Ireland by the 1730s, North America and the Baltic lands by the 1740s, Northern Europe by the 1760s, and India around the same time".

Early London porters were strong beers by modern standards. Early trials with the hydrometer in the 1770s recorded porter as having an original gravity (OG) of 1.071 and 6.6% alcohol by volume (ABV). Increased taxation during the Napoleonic Wars pushed its gravity down to around 1.055, where it remained for the rest of the 19th century. The popularity of the style prompted brewers to produce porters in a wide variety of strengths. These started with Single Stout Porter around 1.066, Double Stout Porter (such as Guinness) at 1.072, Triple Stout Porter at 1.078 and Imperial Stout Porter at 1.095 and more. As the 19th century progressed, the porter suffix was gradually dropped.

The large London porter breweries pioneered many technological advances, such as the use of the thermometer (about 1760) and the hydrometer (1770). The use of the latter transformed the nature of porter. The first porters were brewed from 100% brown malt. Now, brewers were able to accurately measure the yield of the malt they used, and noticed that brown malt, though cheaper than pale malt, only produced about two-thirds as much fermentable material. 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 and add colouring to obtain the expected hue. When a law was passed in 1816 allowing only malt and hops to be used in the production of beer (a sort of British Reinheitsgebot), they were left in a quandary. Their problem was solved by Wheeler's invention of the almost black (kilned) patent malt in 1817. It was now possible to brew porter from 95% pale malt and 5% patent malt, though most London brewers continued to use some brown malt for flavour.