Low oxygen Roach Four amber trappist enkel: preboil, smb and btb, mash cap, nosparge. Spunding in keg failed partially because of leak. Result: more than good enough to continue using this method. Maybe amount of esters could be better. The monks of Westmalle use shallow fermentation vessels to minimize the amount of CO2 in the fermenting beer, because apparently CO2 inhibits the formation of esters.
Awesome! I’m going to be playing with temperature and pitch rate to try and get a good ester profile.
Serving temperature was 4C. Way too low. Will let the temperature rise and will try again tomorrow @10C or so.
What recipe did you go with?
15 liter batch size
39 EBC
20.6 IBU
1.053 SG
79% pilsen
7.2% caramunich 3
4.3% flaked wheat
2.9% special b
6.6% candi 180
16 IBU Styrian Goldings @50
3.7 IBU Hallertauer Hersbrucker @25
0.5 IBU Hallertauer Hersbrucker @5
4 grams coriander
Belgian Abbey II (Wyeast Labs #1762)
usual amount of BTB in mash and boil
Hochkurz mash, nosparge.
Fermentation starting @17C, let rise to 24C
Maybe you started too fermentation too low. If you take BLAM as a reference like I typically do (among other concurrent references), Rochefort starts fermentation a little higher.
What was your pitch rate? That’s another thing that will inhibit esters.
I have been deciding on the right balance point using Chapter 8 from BLAM as a guide:
Key Points:
1.) Ester production is inversely related to yeast growth (more growth = less esters)
2.) Higher gravity = more esters
3.) Higher attenuation = more esters
4.) Fusels increase perception of banana esters
5.) Higher fermentation temp = increased ethyl acetate (solventy), floral and fruity esters
6.) Lower fermentation temp = inhibits esters and promotes phenol perception
7.) Higher pitch rates = lower ethyl acetate
8.) Lower pitching rates = more esters
9.) Horizontal tanks = increased esters
10.) Open fermentation = lower esters
11.) Cylidro-conical tanks = lower esters
The thing I’m looking to do is maximize pitch rate, temp and gravity to get the right ester profile and inhibit sediment left in the bottle when I bottle spund.
I think pitch rate was high enough. 15 liters, shaken-not-stirred 750 cc pitched at high kraeusen.
I made the Rochefort 4 once before, fermented at 18C and submitted it to a competition. The judge said he tasted isoamyl acetate, which should not be prominent in Rochefort, so this time I lowered the temp a bit.
I also ferment in a keg. That doesn’t seem to be ideal for esters.
Just noticed that these two points seem to contradict each other.
True. I summarize the chapter pretty quickly this morning and may have fat fingered that one. I’ll review and correct if needed.
If you haven’t read it before, there is some interesting information on ester formation here:
I just reread this article for the first time in a long time, and this little nugget jumped out at me:
[quote]Finally, the type of sugar being metabolized plays an important role in the creation of higher alcohols, which, in turn, plays a role in ester production. Sucrose and fructose result in increased higher alcohol production, and so does glucose to an extent. Maltose metabolism results in considerably lower higher alcohol production than does glucose and fructose.
[/quote]
I wonder if this means that the simple sugars that are typically added by Belgian brewers tend to enhance the typical ester profile we get from Belgian ales. Of course, elsewhere in the article he mentions that a higher C:N ratio (sugar additions would increase this) tends to lower ester production, so maybe those factors cancel out. Still, food for thought…
Yes, I think you are right. A Rochefort 8 would have at least 10% of candi sugar, my lower gravity version has only 6%.
The fact that beers with a higher portion of simple sugar also attenuate more plays into what Mark said in his article. Need to reread that today.
That also has implications for us using invert syrup in our British Ales.
Maybe that’s why I’m finding more beers “too clean”.
I wonder if this means that the simple sugars that are typically added by Belgian brewers tend to enhance the typical ester profile we get from Belgian ales. Of course, elsewhere in the article he mentions that a higher C:N ratio (sugar additions would increase this) tends to lower ester production, so maybe those factors cancel out. Still, food for thought…
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I think a big driver would be that many of the Monastic Belgian beers are higher gravity (promotes more esters) and attenuate well (promotes more esters) due to higher portions of simple sugar as fermentables.
Hey this is good news. I have a Belgian Dubbel with 7% candi syrup scheduled to brew in January and a English ale with 10% invert syrup in February.
What’s your pitching rate look like? In my experience, lowering my pitching rate has had the biggest influence in getting more esters into standard gravity ales like hefeweizens and English ales. As a matter of fact, I’ve always noticed that my standard gravity Belgian ales (like Belgian pale ales, for example) have less yeast character than I’m expecting. I’m pretty sure it’s because I don’t lower my pitch rate for those ales the way I do for a hefe or bitter. Big Belgians and saisons can probably get away with a typical ale-sized pitch, since you have gravity and/or attenuation to push the ester production.
I was crunching the numbers given in BLAM for pitching rates of Duvel and Rochefort and it was scary low.
I think Duvel was 0.44 M/ml/°P and Rochefort pitched 0.73 M/ml/°P for all 3 beers.
Wow! I didn’t realize that even the bigger Belgians got pitched at such a low rate. I generally brew Belgians in series, starting with a moderate gravity beer and working up to a Quad/BGSA. I’ve always pitched at a typical ale rate for my first beer, thinking I needed a big pitch for the big beers. I’m starting to think that it is more yeast health and acclimation to higher ABV that is what I need rather than sheer pitch size, and I can try pitching at my usual weissbier rate in the future.
Thanks for sharing that!
No problem. I’ve read BLAM many times and I’ve always glossed over it but when I started to try and identify the “levers” to be pulled in perfecting that Monastic ester profile I crunched those.
So essentially the 6, 8 and 10 are identical in pitch rate and recipe composition, only they are scalar multiples so each gets a progressively larger dose of sugar.