Porter turned bitter

[Henmack]

I tapped my chocolate porter about two weeks ago. Tasted pretty good and was happy with it but decided to give it about one more week. After another week I tasted it again and now it has a bitter flavor and aftertaste. What may have gone wrong?

 

[Steveruch]

What was your recipe? All-grain? Extract? Yeast? Fermentation temperature?

 

[Henmack]

What was your recipe? All-grain? Extract? Yeast? Fermentation temperature?

I miss quoted. It was a chocolate stout. I used a deck Hand stout All Grain recipe and chocolate nibs were added. Wyeast 1084 Irish ale . Fermentation temp was 68-70

 

[Damian13]

Are you tossing the first few ounces you pour away.? I have a porter on tap at the moment and the beer that sits on the line for some reason gets a bitter almost metallic taste. If I toss the first few ounces of the night the rest tastes like it's supposed to.

 

[Henmack]

My first pour I pitched the first glass. Since then I've had 4 or 5 pints. Tasted pretty smooth and was happy with it. Then I went 1 week and starting drinking again. To my surprise it now is bitter. Could the cause be oxidation?