Rhubarb Witbier - Light shocked without light?

So as the subject title indicates, I brewed a rhubarb Witbier recently. It is super complex with a bit of a sour note at the end, but also has a tiny bit of a skunky smell. I didn't even notice it at first but once SWMBO pointed it out It was all I could focus on. This beer, like all of mine, was fermented in a dark corner with a towel wrapped round the carbon and was ultimately bottled in brown bottles. Is it possible to get light shocked beer without light?

Recipe: http://hopville.com/recipe/1083908/witbier-recipes/rhubarb-wit

I did do the adjunct mash, tho it didn't go very smoothly.

Doug

My preference would be to add the rhubarb the last 5 minutes of the boil or so. Maybe 10. There is going to be some sourness as it's a sour plant. Perhaps step the bittering hops addition back a little to compensate? I have rhubarb, so I'm interested to know others' thoughts here too.

Wait, the adjunct mash includes malt that is boiled? That sounds like tannin-extraction to me. Could be the taste you're getting?

Rhubarb adds a fair amount of acid, mostly malic acid with a small percentage of oxalic acid as well. Works well in a country wine, and should in a wheat as well I would think. Could that be what you are tasting?

I don't see how it could be light struck skunked hops if your beer has not been exposed to light. Were the brown bottles kept out of the light too? I keep mine in a 12 pack box with a towel over them while they bottle condition in the kitchen.

I think you're just getting a weird combination from the dememera sugar, hop bitterness, yeast phenols and rhubarb.

tre9er said:

Wait, the adjunct mash includes malt that is boiled? That sounds like tannin-extraction to me. Could be the taste you're getting?

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No tannin extraction in an adjunct mash. Tannin extraction occurs with high pH and high temps. In the adjunct mash you only have high temps. It's just like decoction. People wouldn't do a decoction if they got tannin extraction.

slarkin712 said:

No tannin extraction in an adjunct mash. Tannin extraction occurs with high pH and high temps. In the adjunct mash you only have high temps. It's just like decoction. People wouldn't do a decoction if they got tannin extraction.

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Very true. I didn't pay attention to how much water/grist ratio was being used, either.

Thanks for the replies. I had one tonight and the skunkiness was gone, so not a light shock issue.

I thought that rhubarb might be a good fit for te style. I was up for a challenge and after reading about the style in Radical Brewing, decided to give the adjunct mash a try. My error was in using too much of the six row in the adjunct as there was no way I would have come close to getting the full mash to 150 ish after combining them. I ended up putting it in an ice bath for ten minutes or so to get it closer, so my mash times were a little off.

I opted to use a pound of rhubarb in the last five minutes of the boil and 16oz of filtered rhubarb juice (from 2-3 pounds of raw rhubarb) added to secondary (boiled five minutes before adding to minimize contamination risk). I'd say I like this beer, but am not in love with it. Another week of conditioning might help it meld together better.