It wasn’t just the recipe that was changing. How Porter was aged evolved, too. Rather than age all their Porter for a medium length of time, brewers started to age just s proportion of it for a relatively long period and then blend this with “Mild“ or young Porter. This entailed brewing two types: Keeping Porter and Running Porter.
In the first seven decades of the 19th century London brewers produced two types of Porter for the domestic market:
- Running Porter which was sold young
- Keeping Porter which was aged 6 to 12 months
The recipes for the two beers were essentially the same, except that the Keeping version was much more heavily hopped as it would need to survive longer. The hopping rate was 50-100% greater than in the Running version. There might also be a higher proportion of roasted malts in the Keeper.
Unlike like Pale Ale which was aged in trade casks – usually hogsheads – Keeping Porter was, as in the 18th century aged in enormous vats, holding thousands of barrels. The larger the volume of beer, the less that is in contact with oxygen.
During the ageing process Brettanomyces, which was either part of the pitching yeast or lurking in the oak staves of the vat, would slowly work away at any remaining fermentable material and produce vinous flavours, which were highly valued by drinkers, along with a certain degree of acidity
Keeping Porter wasn’t usually sold straight, but blended with Running Porter in the brewery before being sent out to customers. The usual recommendation was to use no more than one third of Keeping Porter in the blend. This would add the aged flavour that was valued by customers without being too harsh or tart.
Keeping Porter was brewed in large quantities up until 1860, after which it quickly fell out of favour and by the end of the 1870’s had disappeared entirely. The public seems to have lost its love of the aged flavour. Though Porter remained extremely popular in London, it was all sold “mild”.
Some stronger Stouts were still aged, but as the quantities involved were much smaller, more modestly-sized vats were employed. London Porter brewers ripped out their large vats, vats which had once been a source of great pride.
|Runners and Keepers in the 1850s|
|Year||Brewer||Beer||OG||FG||ABV||App. Atten-uation||lbs hops/ qtr||hops lb/brl||pale malt||brown malt||black malt|
|Whitbread brewing record held at the London Metropolitan archives, document number LMA/4453/D/09/050.|
|Barclay Perkins brewing record held at the London Metropolitan archives, document numberACC/2305/1/542.|
|Truman brewing record held at the London Metropolitan archives, document numberB/THB/C/057.|
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