Monday, July 23, 2012

Any Port in a Storm (part 1)

We moved into our current home just under a year ago, completely missing last summer, so we didn't realise that the giant overhanging tree from our neighbours was actually a plum. Despite the soggy weather (and the resulting brown rot taking about a third of the crop) we've had a glut of plums on our side of the fence.

Dr David has been making plum jam and, not to be outdone, I decided that I'd make alcohol! So here are my preparations for plum port:

I poured boiling water over some freshly picked fruit to kill some of the existing microflora. I then stoned and froze them 1l bags. 

1l of stoned, frozen fruit
I'm justifying the fact the approximate measurement of the plums with the fact that the plums themselves are so variable. What I'm going to control for later are liquid volume and specific gravity.

Defrosting and mashing

I defrosted the plums in a 5l bucket (from a homebrew shop on Amazon) standing the whole thing in a bain marie (the washing up bowl, full of warm water).  Not as fun as doing it the Lucille Ball way - but my bucket is too small for my feet!

I brought the volume up to 4l with boiling water.

I squeezed the fruit between my fingers as soon as the must was cool enough to immerse my hands in. The must is pretty foamy but it didn't smell like fermentation and the foam appeared pretty much instantly, so my guess is that this is not the natural yeasts on the plums reacting with the sugars in the fruit - I think what we have here is a pectin foam...

Things I don't want - pectin, yeast or bacteria

Pectin makes jam all jammy but is no friend of wine so I had also ordered myself some pectolsae (an enzyme that breaks down pectin). Otherwise we'd be looking at a very cloudy batch of port. I also used campden tablets (sodium metabisulfate)  for two reasons - 1) to get rid of the residual chlorine in the good old London Tap I was using and 2) to kill off any remaining fungal spores or bacteria in the must.

Pitching the pectolase - foam disappears instantly!
As soon as I added the pectolase (made up in some warm water as per the instruction) the foam dissipated. More evidence in favour of the pectin foam hypothesis...

A slug of lemon juice - cargo cult...
I added a slug of lemon juice because several of the recipes I've read called for varying amounts. Some claimed the acidity is necessary (I'm not measuring acidity so I'm playing with a loose variable here!), others claimed that the ascorbic acid helps prevent oxidation. I must admit I have no idea why I am adding this. Any help?

The good chemists of Chipping Campden - I thank you

And so to add the crushed campden tablet as per the instructions. I'm covering with a clean tea towel so that the gasses released when the sulphur dioxide reacts with the chlorine can vent.

24 hours later...

The must looks ok - no nasty films, foams or colonies have formed overnight. Time to pitch the yeast. I've added some sugar and measured my SG at about 1.09 , but I will be adjusting it again before I decant into my secondary fermentation vessel (a 5l plastic jug!)

I want to give my yeast the best start in life. When I worked on the Robot Scientist we used to feed our yeast on Marmite (cannibals!) I've given mine a tablespoon and a half of sugar in half a pint of blood hot water.

Hello s.cerevisiae, my old friend

Happy happy colony...
An hour later and it's time to pitch the yeast into my must (at 1.09 sg)
Hopefully, over the next four days or so, my yeast will piss alcohol and crap CO2 until it's time to strain and put it in the demijohn! In the meantime, it's back on with the cloth - and hope!

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