Hello - I apologize for the long thread but I'm hoping this forum can help me out. I've been brewing a series of New England IPAs - trying to hit similar styles to Treehouse, Trillium, Lawsons, etc. I've done 8 of them in the last 8 months and for the most part they have been excellent. I am using this style as a test ground to experiment with different techniques. The last two that i've done have resulted in an astringent bitterness. I have narrowed my potential culprits down to four things but wanted to get more eyes on this troubleshooting:
1. Sparge water too high - I use RO water and build up from there. I normally don't do any sparge acidification in my fly sparge and I understand this could potentially cause it. On the flip side I haven't really changed my process and the RO water is low in alkalinity so I'm skeptical that this is it.
2. Grain crush too granular - I have my monster mill set at .035 and maybe it's crushing too much. Combine with #1?
3. I have been experimenting with some Citric acid in the boil kettle to drive the PH down a bit. I used 13 grams in a 10 gallon batch and 9 grams in a 10 gallon batch recently. I don't know if that much Citric acid could cause some astringency?
4. Overhopping - I doubt this is it. The last two batches I do a very very tiny 60 minute addition of .1 oz of Columbus just to keep foaming down. Then I did a flameout addition while whirlpooling through my dudadiesel wort chiller for 30 minutes. After the 30 minutes I chilled it down very quickly to pitching temp. I used: 3oz Amarillo leaf (8.9%AA), 2.5oz Galaxy pellet (14.9%AA), 1oz Cascade leaf (5.5%AA), 1oz Centennial pellet (8.3%AA). I put these in a stainless steel hop spider and I stir the hops occasionally. According to Beersmith this would drive 52.3 theoretical IBUs using the RAGR formula.
Here are some specifics on my process
65-70% 2-row (either US or MO - this doesn't matter)
15-20% white wheat malt
12% flaked oats
~3-4% Crystal type malt (carapils + honey OR golden naked oats)
RO built up with salts to hit 112 calcium, 18 magnesium, 200 sulfate, 100 chloride
I consistently hit 5.2 with 15 minutes into my mash
Add salts to mash
HERMS recirculation at 150F
Mashout step by increasing the HLT with HERMS to 168
With RO water - no acidification
Continuous fly sparge with two pumps until I hit my pre-boil volume
Add sparge salts directly to beginning of boil
Add 9-11 g of citric acid directly to beginning of boil
As I said above
~15 oz dry hops during the tail of fermentation just as the Krausen falls (7 days)
Anyway, that's probably enough. Looking for someone smarter than I am to help me work through this. It's starting to get discouraging.