Help finding source of astringency

I recently entered an American Brown Ale in a competition and just got the results. The main flaw that the judges noted was an astringency. Here are the comments:

"Very dry, resiny finish. Bordering on astringent".
"Some astringency".

I'd like to know where that came from since that is something that I thought I was avoiding by using some of the techniques that I do (clean Horizon for bittering, low sparge temperatures, shifted majority of IBUs to the last 15 minutes of boil). I'd appreciate it if you guys could give some possible sources of the astringency so that I can understand my recipes and process better. Here it is:

Recipe Type: All Grain
Yeast: Wyeast 1272 American Ale II
Yeast Starter: Yes – to achieve pitching rate of 0.75 million cells per mL per °Plato
Batch Size (Gallons): 4.5
Original Gravity: 1.057
Final Gravity: 1.013
IBU: 39.7 (Tinseth)
Boiling Time (Minutes): 75
Color: 18.9 SRM
Primary Fermentation (# of Days & Temp): 1 day at 65°F, 2 days at 66°F, then 19 days at 67°F
Secondary Fermentation (# of Days & Temp): None
Tasting Notes: Judges Comments: The bitterness is a bit high, but the malt makes up for it. However, it becomes astringent in the end. Try more of a lower AA hop to see if you get more flavor and balance instead of all bitter. Watch the roast as it shows in the aroma.
Hop bitterness is a little overdone. Malt is well done. Esters are a little high. Hop aroma and flavor seem a bit lacking.


Ingredients:
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1.80 lb Pale Malt, Maris Otter (3.0 °L) 17.8%
6.32 lb American 2-Row (1.8 °L) 62.6%
0.60 lb Briess Crystal 40L (40.0 °L) 5.9%
0.30 lb Briess Crystal 60L (60.0 °L) 3.0%
0.56 lb Fawcett Pale Chocolate (218 °L) 5.6%
0.25 lb Flaked Barley (2.2 °L) 2.5%
0.26 lb Munton’s Extra Light DME (3.2 °L) 2.6% (for starter)

10 g Horizon [12.1%] (60 min) Pellets 17.4 IBUs
34 g Centennial [9.2%] (15 min) Pellets 22.3 IBUs
29 g Centennial [9.2%] (0 min) Pellets 0 IBUs

Mash at 151°F for 60 minutes
Double batch sparge <168°F*
*I didn't measure the temperature of the sparge, but based on my process, I'm always below 168°F
Recipe designed for 69% efficiency

Mash thickness 1.25 quarts/lb with following mineral profile:
Calcium: 144 ppm
Magnesium: 9 ppm
Alkalinity as CaCO3: 264
Sodium: 52 ppm
Chloride: 35 ppm
Sulfate: 38 ppm
SRM Range: 18-23

Sparge with distilled water and add salts to the boil to achieve overall mineral profile as follows:
Calcium: 104 ppm
Magnesium: 13 ppm
Alkalinity as CaCO3: 228
Sodium: 62 ppm
Chloride: 51 ppm
Sulfate: 55 ppm
SRM Range: 17-22

Use 1/2 Whirlfloc tablet and 3/8 tsp Wyeast Nutrient Blend with 10 minutes left in the boil.

Bottle condition with priming sugar to achieve 2.5 volumes of CO2.
Beer was approximately 4 weeks old at the time of the competition.

jescholler said:

Tasting Notes: Judges Comments: The bitterness is a bit high, but the malt makes up for it. However, it becomes astringent in the end. Try more of a lower AA hop to see if you get more flavor and balance instead of all bitter. Watch the roast as it shows in the aroma.
Hop bitterness is a little overdone. Malt is well done. Esters are a little high. Hop aroma and flavor seem a bit lacking.

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I find the roast comment strange considering you used a small percentage of pale choc malt.

As for hops, i know Randy Mosher advocates low alpha-acid hops and more ounces.

That's a lot of alkalinity. Maybe that is contributing to the harshness/astringency (tannin extraction)? But your efficiency is on the low side so that implies that you're not over-sparging. I don't know, just food for thought. If it's not the hops, maybe try diluting with distilled to get the alkalinity down.

SpanishCastleAle said:

That's a lot of alkalinity. Maybe that is contributing to the harshness/astringency (tannin extraction)?...If it's not the hops, maybe try diluting with distilled to get the alkalinity down.

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Even for a 19 SRM beer? Based on Palmer's spreadsheet, SRM range for the mash profile was 18-23. Would you recommend going for the lower end of the range (maybe 14-19)?

SpanishCastleAle said:

But your efficiency is on the low side so that implies that you're not over-sparging.

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Yeah, I've tweaked in my sparge amount to get around 70%. When I started AG, I was getting in the 80's for efficiency, but I quickly adjusted my sparge amount to get closer to 70. I do sparge with distilled water though (which Palmer says is OK, but maybe this is a corner case).

jescholler said:

Even for a 19 SRM beer? Based on Palmer's spreadsheet, SRM range for the mash profile was 18-23. Would you recommend going for the lower end of the range (maybe 14-19)?



Yeah, I've tweaked in my sparge amount to get around 70%. When I started AG, I was getting in the 80's for efficiency, but I quickly adjusted my sparge amount to get closer to 70. I do sparge with distilled water though (which Palmer says is OK, but maybe this is a corner case).

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Read some of aldelange's recent posts in the Brew Science forum. It appears that Palmer waaaaayyyyy overstated the SRM:RA correlation. Also, Kai did some tests (full article on his Braukaiser site) that showed that for a given amount of color, roasted malts don't contribute as much acidity as caramel malts and also that it doesn't matter much the darkness of the roast, all roasted malts contribute about the same amount of acidity.

And I'm not really even saying the alkalinity was the problem, just trying to give you additional ideas where to look. That 264 ppm alkalinity as CaCO3 in your mash water just seemed really high.

Maybe post a water related question about this brew in the Brew Science forum and see what ajdelange says.

You sparged with distilled water? First, you should probably create your water in one large homogeneous batch. Second, brew it again with pH 5.2 stabilizer in the mash and sparge water and see if that changes things.

I'd get a second opinion before changing up my process. Judges in comps are tasting a lot of beer, I'd not rely on that if you don't taste it. Find some other brewers to taste.

SpanishCastleAle said:

And I'm not really even saying the alkalinity was the problem, just trying to give you additional ideas where to look. That 264 ppm alkalinity as CaCO3 in your mash water just seemed really high.

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Thanks for the info. Those posts by A.J. are going to take a while to sink in. Too much science for me on my day off.

I didn't mean to make it seem like I was arguing your point. Those types of recommendations are exactly what I was looking for.

samc said:

I'd get a second opinion before changing up my process. Judges in comps are tasting a lot of beer, I'd not rely on that if you don't taste it. Find some other brewers to taste.

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Good point. I'd like to improve my ability to taste so I can pick things like this up on my own. Unfortunately this batch is long gone so I'll have to brew it again to do that.

I do understand that the judges could be wrong. My beer was 18 out of a flight of 19 (all American Ales, category 10), so maybe after tasting a bunch of pale and amber ales, the roast in my beer seemed astringent. Either way, I'd like to understand my beers better to make improvements.

Astringency can also be from over sparging. Checking PH is the answer there.