First off: Sorry for the link, apparently I can't upload images at the moment.
This is my first ride with a wireless hydrometer, so maybe this is just me not being used to having access to gravity readings all the time, having become a bit obsessed with the numbers. Looking at Brewfather on the other hand though, my gravity really hasn't changed for like 36 hours now, before reaching its estimated final value. Now I'm afraid that my fermentation has stalled, and as the gravity was never really high to begin with, I fear being stuck with something not only low in low in alcohol but also tasting thin & weak. This is supposed to be a "Klosterbier" (not a real beer style, but closest described as some sort of brown ale), with which I'd have preferred to err on the stronger side rather than on the weaker.
The main reason for the low initial gravity I believe is too little boil off: While pre-boil gravity was OK (Brewfather predicted 1.039, refractometer gave me 1.037, might even be considered to be within measuring tolerance), the post boil reading should have been 1.051 but was only 1.041.
After boiling, I took around half a liter of wort, chilled it down in a mason jar and added dry yeast, agitating it every now and then. The next day, I pitched now very agile yeast into the main bucket and fermentation started out perfectly. The ups and downs in the graph may just be results of krausen and/or condensate dripping back onto the RAPT pill or creating ripples in the wort surface.
Now, I'm really asking myself what went wrong. I don't think I caught myself any infection, the bucket was properly sanitized as well as the collection vessel & I was very careful handling all of it. The yeast also very happily ripped through the major parts of the sugars, so I don't think it's a yeast issue either. My grain bill looks as follows:
- 2.25 kg (50%) — BESTMALZ BEST Munich — Grain — 15 EBC
- 2.21 kg (49.1%) — The Swaen Swaen Vienna — Grain — 10 EBC
- 40 g (0.9%) — Weyermann Carafa Special II — Grain — 1100 EBC
The performed mashing steps:
- Mash In — 38 °C
- Protein Rest — 50 °C — 40 min
- Beta Rest — 63 °C — 30 min
- Alpha Rest — 72 °C — 30 min
- Mash Out — 78 °C
I'm not sure what to do, or if I should do anything at all. I can live with the beer having 3.5% ABV like it has now probably. My storage is dark and reasonably hygienic, so I don't think I have to elongate the beer's shelf life that way. The alcohol might then even overpower the taste of the grains if I added table sugar or anything for another percent of alcohol.
What I'm slightly concerned with though is overwhelming hop aroma because there apparently is not that much dissolved sugar to counteract the bitterness.
Any suggestions?
What is your brewing setup? I've used your grain quantities in BeerSmith with a Braumeister 20L setup for the out of the box efficiency (without stirring the malt during mashing or a finer grind or extra boiling) and it gave me a post-boil of 1.042, which seems to fit with your result so I'd guess you had an efficiency issue. How did the mashing go?
I've noticed that when boiling for the standard 1 hour, I get about a 10% increase in gravity (for the digits after the 1 - that is, pre-boil of 1.064 leads to post-boil of 1.070 ish), so in your case 1.037 to 1.041 would check out for me.
For my brewing setup, 30 minutes at 63C doesn't really cut it, I've tried it and noticed 60 minutes or even 90 minutes work way better. But then I mostly use kveik and the indication seems to be for longer mash times (something about it being unable to digest sugars made of 3+ units).
I'm not sure I get your last point. If your FG is higher than expected, you should reasonably have more sugars left over from fermentation, so more residual sweetness.
Regardless, I'd suggest RDWHAHB, and see what you get out of this. Do share your final results, I am curious what it's like.
Out of lazyness, I just let all my beers sit in the fermenter for 2 weeks and that seems to work out just fine. Some finish bubbling after 2 days, some after 12.
Edited to add: just noticed from your yeast link, you also use an all-in-one system, does it suffer from the same low efficiency issues as the Braumeister, I wonder?
I've got a BrewZilla Gen 4 35L. I don't know what you'd consider low efficiency, but the unit's default profile in Brewfather is ~76%, whereas the software calculated roughly 65% efficiency for the batch in question. I've got no idea though how that compares to the Braumeister 20L other than the values in Brewfather are rather similar.
What was a first was crushing the grains myself, but mashing on itself went fine. Looking back, I might have wanted to check for starch with iodine, which I even had available. Might do next time. I also might want to add though that I used 13.5 liters of strike water and did what from my understanding is a batch sparge (raising & draining the mash tun, then adding hot water from a second vessel with a jug) with another 15 liters at 80° C. Not perfect for efficiency, I know, but as described my pre-boil gravity was fine. I must just have been to shy on the heat while boiling.
In the back of my head, I have the number of 10% boiloff being desirable, which would match with your 1 hour boil observation.
My last point is that I'm afraid the beer might be too thin as in too much liquid for too few sugars dissolved in it. I didn't boil off enough water, so I did not concentrate the wort far enough to reach the desired post boil gravity.
The software calculated efficiency for the Braumeister is spot on for me if just using it like set it and forget it, so about 65%. I can up that with stopping the pump during mashing, opening the thing and stirring the mash about once every 30 minutes in my 90 min mash. Also by milling the malt a bit finer. But too fine, and I get a stuck mash. With this, I managed around 75, or how much the software sets as standard for pot and cooler method, so I'm happy with that.
I also start the brew with 23ish liters of strike water, dump 6 kg of malt in there and sparge with 5-6 liters at 80C. Boil 1 hr and end up with 18-19 liters in the fermenter with the rest full of trub in the Braumeister (2-3 liters maybe?) I never measured how much is left and I can sparge with 4 or 6L. I just eyeball it according to how much wort is in when I lift the malt pipe.
In your case, I'd say maybe the mash did not go very well.
I wouldn't be too worried about the body. It could be that your fermentation just stopped a bit higher because all that's left is longer sugars, unfermentable, but good for the body. One way to find out...