Bottled porter - no carbonation!

[TheHiphopopotamus]

I brewed Denny Conn's Bourbon Vanilla Imperial Porter back in November. Unfortunately, the batch seems (mostly) flat. I'm not 100% what caused it and more importantly what should be done to fix it.

Starting gravity was 1.077, finished at 1.028 (high, but didn't move for a week even with increased temperature and rousing yeast so I accepted it). Cold crashed to a few degrees above freezing for a couple of days, then racked beer (only 15L/4 gallons due to efficiency problems) onto 30g / 1 oz of dextrose (boiled in water of course). This amount was based on an online calculator - lower beer volume, low temperature, and the fact it is a porter all contributed to this low amount.

Bottled mid-December, and living in the southern hemisphere this meant it has enjoyed warm (though not extreme) temperatures for conditioning. First bottle I opened would be over-carbonated for an IPA let alone a porter. This bottle was the last of the batch from bottling. However, all the bottles since have been effectively un-carbonated, completely flat!

My thoughts on possible causes:

• Cold crashing might have reduced the yeast that made it to the bottles?
• Not enough dextrose (stirring to rouse yeast might have caused a loss of C02 from the fermenter?)
• Improperly mixed dextrose? (I didn't stir, allowing the gentle whirlpool of beer to do the mixing for me, but this worked fine in the past)

But the main issue - what's the best way forward at this point? Flat beer isn't exactly what I was going for, and I've spent too much on this batch to not enjoy drinking it!

 

[flars]

You based the amount of priming sugar on the cold crash temperature? Amount of priming sugar should be based on the final resting temperature after fermentation is complete.
You may be able to add a measured amount of priming solution to each bottle with a small syringe.

 

[kombat]

Amount of priming sugar should be based on the final resting temperature after fermentation is complete.

Actually, it should be the warmest temperature the beer ever reached after fermentation completed. The reason is that CO2 is less soluble in warmer beer, so as the beer warmed, it effervesced CO2. If you chilled it again afterwards, it didn't "suck back in" any CO2, and the yeast aren't producing any more, so the CO2 level stays the same as it was when it was warm.

Based on the fact that the OP said the last one he bottled was a gusher, and the rest were flat, I strongly suggest the priming sugar wasn't thoroughly mixed.

 

[madscientist451]

Options at this point:
-Buy a case of porter you like and mix your beer 50/50 with it as you drink it, or get a cheap light lager and do the same.
-I think adding more yeast would help so you could pour it all into your bottling bucket and add approx. 1/4 pack dry yeast (rehydrated) and add the appropriate amount of sugar and re bottle. After carbing, I'd keep it refrigerated and drink use it up quickly because oxidation and/or infection issues.
I think the initial problem was not enough sugar. Also let the beer warm up to room temperature before bottling, and the sugar should dissolve in easier. Good luck, Cheers!

 

[TheHiphopopotamus]

Thanks for the replies. I used the priming calculator here which suggests some CO2 from the head space does dissolve back into the beer when cold crashing. I think because my cold crash probably wasn't particularly long or for some other reason, the amount of CO2 in the beer was overstated for calculation, in future I'll just enter the fermentation temperature as suggested (maybe decreasing the sugar by just 10% or so if cold crashed). It does also seem that it was undermixed, compounding the issues; it will be interesting to see if any other bottles have any level of carbonation.

Thanks for the suggestions madscientist451 - I might go with the option of mixing it with store-bought porter, I'll try it out anyway. It will mean I have to drink twice as much beer at a time but that's not necessarily a bad thing

I might try to add some sugar to a few as well, just to see how that turns out. May as well treat this as a learning experience.

Thanks everyone!