Perpetual Old Ale Research and Project Write Up

Researched Recipes

The recipe probably hasn't stayed the same over 100 years, so there's plenty of variation available.

Suggested Recipe

OG 1.095, Target ABV 9%, 45 IBU Malt: Maris Otter, torrefied wheat, black malt (25kg in 40 hectolitres, so probably only 15g in a 5 gallon batch) Hops: Lots of fuggles and goldings at the start of the boil, some late hops. Process: 2.5 hour boil

Alternative Recipe

Grainbill: 86% Maris Otter, 2% Black Malt, 12% Brewer's Sugar Syrup (mash at 67°C for 60 min, add sugar to boil at 15 min remaining) Early hops: Challenger (60 min) Late hops: Fuggles & Goldings (10 min) IBU: 48

Other Notes

SG of a sample of most recent Prize Old ale was 1.017. Given an ABV of 9% would suggest a starting SG of 1.084.

Yeast

English ale yeast. Suggested Brewlab Thames Valley 2 or Wyeast 1332 Northwest.

Wyeast 1332 people have reported as having a 'tartness' that is also a distinct feature of Gales HSB.

Alternatively Brewlab Thames Valley 3, Imperial A09 Pub or White Labs WLP002 could be used.

Add bugs after fermentation is complete.

Bugs

Nobody knows exactly what’s in there - brett certainly. A bit of lacto probably. I’d expect there to be other stuff in there too. There may not still be much 'alive' in the latest Prize Old Ale release, so this may need to be reinvigorated.

Have found someone that claims to have isolated the yeast and bacteria from old bottles of Prize Old Ale and then identified them with PCR tests. They said bacteria was a combination of lactobacillus, mostly brevis. There was also brett, but they couldn't grow it. Yeast was viable and behaved like the Wyeast 1332 strain that they were using regularly.

Use of Wood

The original POA was aged in wooden hogsheads, and later a wooden washback. Other solera projects recommend the use of some wood (to house bugs, but also Brett can use some of the cellulose), but to boil the wood first to remove the wood character.

Process

Annually brew a batch of the above recipe. Blend some with aged beer for consumption, leaving the rest for aging.

Ferment

Normal fermentation.

Aging

(Proposed) Age at cellar or room temperature. Consistent high temperatures should be avoided. Low temperatures may inhibit development.

Keep as little headspace as possible to avoid oxygen exposure.

Annually remove half or two thirds of aged beer and blend with half or two thirds of new batch.

Bottling

When blending, it might be worth pasteurising the Bretted part so as to avoid bottle bombs and too much Brett character.

Prize Old Ale Tasting Notes

Taster J

Low carbonation - not flat, but slightly more than cask level. On the nose is bready malt, caramel and toffee, and a touch of balsamic vinegar. Appearance is dark brown, clear, very little/no head. Flavour has more lightly toasty malt and toffee. Low tannic acidity fills the mouth. Medium bodied, not chewy or thin. Bitterness is medium high - well in balance, but surprising compared to the sweetness you’d normally get in an Oud Bruin. Hides alcohol very well. Very drinkable.

Taster S

I doubt there are any roasted malts in here because the foam is nearly white, although very small. Roasted barley has almost no foam colour impact and there is nothing ashy here. There is no edginess from chocolate malts either. Black malt (that could have contributed to some of the fruity aspects mentioned below) gives a reddish tinge, so can't be it.

There is an abundance of sweet and dark chocolate, with a muted spicy kick and a huge note of (proper) kvass, of the kind I've only encountered once before (to a much lesser degree) - in my brown Biere de Garde that was aged for a year (that some of you had during the lockdown presentation on mashing!); there it has come mainly from the combo of malted and roasted rye, as well as Barke Munich; rye is absolutely essential to kvass as I know it. There is plenty of Christmas cake, dark fruits and burnt caramel, suggesting Crytal 240 and Special B/DRC style malts, and a lot of them.

It has a rather thin, but very sweet and chewy finish (love it!), suggesting three things:

• A high degree of unfermentables, likely a high temp mash and/or a stupidly large amount of high EBC crystal malts
• Plenty of age (which we already know)
• One of the brewer's sugars (someone will probably be able to say which invert sugar it is) to bring FG down to 1.018

The marmalade (aroma and flavour) aspect, together with a gentle bitter bite makes me think of Fullers beers and First Gold hops It is only slightly tart (pH meter confirmed my guess of pH 3.7), which is very achievable for British yeasts, however, the slight citrus 'zing' would suggest there was lactic acid involved at some point. Considering it's blended, one of the batches was probably low-hopped and had a lactic bacteria colony.

The only suggestion of brett for me is in the finish, with a sweet wet leathery note - but could easily be oxidation together with age There is a numbing sensation throughout the palate, akin to benzocaine, which I experience from hops and higher alcohols, I think both are at play here (and I would look to remove this).

Project Progress

14th February 2023 - Group did tasting of beer as per notes above. Was noticeable that the carbonation had significantly increased since December. Agreement was for as many people as possible to pitch dregs into 5 litres of lowish ABV beer and see if anything has developed in 6 months. If not then we may look to reconstitute the culture from other sources, but at least there is some amount of the original 100 year old culture in there to start with!