PSA: Do not use anthocyanin rich fermentables in sour beers

Last year I thought I was so smart and creative to replace yellow corn in my two flanders beers with purple peruvian corn. The taste at the beginning was great, and they had a very cool color. I tasted the oude bruin through the fermentation from time to time and it weirdly seemed to be getting MORE bitter. I took my first taste of the flanders red I brewed six or so months ago and it's super bitter.

So I started researching a possible cause of it, and was lead to wine bitterness taint.

Glycerol is reduced by the bacteria in the beer ultimately to acrolein. Acrolein is not bitter on its own but when combined with anthocyanins you end up with a rather bitter combination. These beers taste as if I added a butt load of red grape skins or something they're strong of tannin characteristic.

So hopefully this flavor ages out in a year or so for this one in the bottle. As for the other 6 gal of flanders red, I will be making about 15 gal more very soon (sans purple corn!) and will see if I can blend this into the batch to reduce or make the bitterness drop below perceptible limits.

smokinghole said:

So hopefully this flavor ages out in a year or so for this one in the bottle. As for the other 6 gal of flanders red, I will be making about 15 gal more very soon (sans purple corn!) and will see if I can blend this into the batch to reduce or make the bitterness drop below perceptible limits.

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Is it worth brewing a second beer just to try and save a bad one?

Yes, because if I can't blend it then I can't blend it, but I have 15 gallons of flanders red. I'm not throwing them together straight off. I'll wait till the 15 gal is ready to bottle before even trying to blend.

Also it's not BAD but its not what it should be. Plus I thought the point of blending was to mix beer that had parts of what you wanted like acidity/bitterness/funk together to get the whole picture. So yes it's worth brewing more just with out the purple maize to see if I can blend this six gallons with so I can still use this 6 gallons of beer. It's better than dumping, but I'm not against dumping by any means. I'm not a "time will heal all" person. However, with that said, like all things in wild beer/wine making this flavor may condition out due to further degradation and metabolism by long term brett in the bottle.

I have no idea the outcome of this because I couldn't find any references at all concerning anthocyanins in beer. The closest thing I know I've read is that Cambridge Brewing Company will not use blue berries in their sour beer. I don't know if that is because of the anthocyanins or if its because they are anti-blueberry because they're ubiquitous with Maine. I may have to contact them on that aspect.

I found some more information which may help my flanders red. If I add vitamin C I possibly can tie up and degrade the acrolein much quicker. I will pull a small portion of the flanders red just to do a little side test.

Huh, that's really interesting; just about any red, orange, purple, or blue fruits have anthocyanins and they don't seem to be an issue for cherry, raspberry or blueberry lambics. Upon checking Wikipedia, it appears that blue corn is really high - more than triple the amount of cherries & wild blueberries. There must be a taste threshold somewhere between blueberries and blue corn

I have no idea what the threshold would be but purple corn is seriously high in anthocyanins.

Anyway it's been a week since I added some ascorbic acid (vitamin C) from GNC and sourced from rose hips (this is a crystalized product). The beer has lost a TON of the bitterness that was associated just a week ago. Now the bitterness left I think is just the slight hop bitterness.

This is a very interesting topic. Can I ask your sources? (Not that I'm doubting you, I'm just a nerd and have to read the source for no reason.)

Crazy chain of events, and it sounds like you did some good detective work! I'd like to see the sources too.

This is what tipped me off. I found numerous sources for Vitamin C reducing Acrolein toxicity. So I gave it a blind shot in the dark. I didn't try and bust out any chemistry to figure out how the bonding would work out/if the ascorbic acid to acrolein bond is stronger than acrolein to anthocyanin bond. I put in what seemed to be a slightly excessive amount (1 tablespoonish) into the fermentor hoping for the desired reaction and not fearing any off flavors do to excess vitamin C.

http://lpi.oregonstate.edu/fw10/vitamincbeer.html

I was a biotech major so it was pretty easy to figure out, and I'm a big nerd too.

How much vitamin C would need to be added before it started working as a preservative?

Ascorbic acid is often used to preserve foods, so I was wondering if there is any risk of killing off your yeasties and beasties.

This is very interesting. I had a Cantillon Blabaer for the first time a little while ago. I found it to be EXTREMELY tannic. From what I've read, Blabaer is actually bilberry, not blueberry, lambic. I just looked it up and "the anthocyanin content of fresh bilberry fruits being almost 4× higher than that of blueberries." http://www.dionex.com/en-us/webdocs/110929-AN281-HPLC-Anthocyanins-Bilberries-18Jul2011-LPN2848.pdf

Glad I'm not the only one to come across this weird tannic bitterness.

As to the level necessary to provide preservative effects, I don't really know. I have a feeling a decent amount more than I used.

Well at two months or so since adding the vitamin C I blended this batch in with a batch of oud bruin that had aged a while. So the two averaged out to be about 6% abv and have a nice color/flavor. Nothing like having LOTS of sour flanders ale around for a while. I can't wait to brew a nice big batch of it again.

Thanks for posting this. You saved me from wasting a brewday, ingredients (including the ECY02 I am excited to try) and so much time and anticipation. Bummer that it did not work out - I was also considering myself megaclever for thinking to use the purple corn, mostly for the color. what'd you think of the color contribution to the final brew?

Well the color is the other thing. Anthocyanin as a deep dark purple like in the corn will turn to a pink color as the solution, in our case beer, becomes more acidic. So the cool color we both wanted actually turns from purple in a neutral solution to pink in an acidic solution. If somehow you had an alkaline beer it'd turn green which is pretty wild. So the color contribution is a non-benefit coupled with the acrolein-anthocyanin reaction, purple corn is a no-go for me. I may be bold and try again with a pale beer and add purple corn. I was thinking I would see how it ferments with a sour culture as the sole source of color but add an educated guess of vitamin C to counter act the acrolein thus preventing the acrolein-anthocyanin bitterness. My guess is it'll still turn out weird and just slighly pink but I might do it anyhow.