Making IN YOUR FACE IPA's.

[redbone]

Greetings all. My general brewing practices over the years have got better and more efficient. I'm producing more consistent with less faults than ever. The one thing I'm missing still is hitting the mark on my IPA's where they are aroma and flavor filled punches in the face. I thought maybe my hop tolerance was just increasing and senses getting numb, but I still get what I'm looking for in some commercial examples. Achieving bitterness isn't the problem, but the aroma and flavor components are lacking. As far as recipe design goes, I feel like I'm adding plenty of hops for bittering and should be enough late hop additions and dry hopping for aroma and flavor. I'm also adding less caramel malts and mashing lower than I ever did in the past.

I'm curious what are some of the techniques you all are using to get the most out of your hops in your IPA's.

Here are some things to get us thinking...

Are there certain ABV's you try to target?
Any malts you try to avoid?
Any special water treatments?
Could any additives like campden affect aroma/flavor?
Could anything like fermcap be stripping out aroma/flavor?
Whole leave vs pellet maybe at certain points in the boil?
Strong boil vs slow rolling?


just random thoughts... I'd love to hear people's thoughts or things they know to do that produces great IPA's every time.

 

[Braufessor]

Are there certain ABV's you try to target? Personally, I am a 5.5% type IPA person - but I don't think this matters.

Any malts you try to avoid? Low caramel helps. I use maybe 2-3% of something in the 15-40L range.

Any special water treatments? There are a variety of ways to get there.... High sulfate 200-300+ and low chloride50 or less is probably the typical strategy. I prefer higher chloride (130) and lower sulfate (70)..... but that just makes "different" beers - I think you can get the effect you are looking for with either.

Could any additives like campden affect aroma/flavor? I don't think so

Could anything like fermcap be stripping out aroma/flavor? I don't think so - unless added later maybe

Whole leave vs pellet maybe at certain points in the boil? Pellet.... just because you can't use 12+ ounces of leaf hops and think you are going to have any beer left in the end.

Strong boil vs slow rolling? Can't see how this would matter.

In addition to the above answers - LOTS of post boil hops. I put nothing in other than a bit of battering hops at 60. Everything else is flame out or dry.
I make 4 x 3 ounce additions:
*Flame out
*Cool wort under 160-170 and hop stand for 30 minutes
*First dry hop at day 5-6 in primary
*Second dry hop around day 12 using this strategy:
http://www.bear-flavored.com/2014/09/how-i-dry-hop-my-ipas-with-no-oxygen.html

So - I am using 12 ounces of hops for aroma/flavor. Avoiding oxygen pick up in transfers is really important. Also, make sure you are using hops with a lot of aroma and flavor. I like Citra, Mosaic and Galaxy personally.

 

[tschafer]

From the 'boro- What high school did you go to? Riverdale class of 1999

Are there certain ABV's you try to target? - 6.0 - 7.5ABV

Any malts you try to avoid? - crystal malts. A strong IPA does not need a lot of this. Mostly for color, target around 3-7% of crystal/caramel in the grain bill. A good IPA has a very simple grain bill.

Any special water treatments? - KNOW YOUR WATER and your pH!!! I can't stress this enough. Target 5.2 - 5.5 Mash pH. It really matters. Get a pH meter, and have some gypsum handy.

Could any additives like campden affect aroma/flavor? - no

Could anything like fermcap be stripping out aroma/flavor? - All finings and filtering will strip hop oils in some fashion. It's just a bummer.

Whole leave vs pellet maybe at certain points in the boil? - This is totally opinion oriented. I prefer pellets. I feel more oil is produced.

Strong boil vs slow rolling? - Doesn't really matter. I only worry about that if i want to boil off more or less of my wort in my boil kettle

FWIW - If you want aroma - you have to open up your wallet, and increase your flameout hop additions. Adding hops at 160-175 degrees and letting them sit in your boil kettle will help. Whirlpooling will help even more. Dual dry hopping helps too. Say your dry hopping with 6oz of hops. Do 3oz for 2-3 days, then drop in the other 3 for another 5-7 days. Cold crash after that, bottle keg.

 

[khillian]

Just my two cents,

Are there certain ABV's you try to target?
- I tend to go from 1.045 - 1.065 targeting 1.008 - 1.012 FGs depending on the recipe.

Any malts you try to avoid?
- Lately I have been mashing higher and blending base malts mostly , with a little Munich. Keep things simple.

Any special water treatments?
- Yes use a brew water sheet to add gypsum and calcium chloride depending on your source water. I have very soft mineral deficient water here in SF.

Could any additives like campden affect aroma/flavor?
- Campden water treatment is a good thing, prevents those nasty chlorophenols.

Could anything like fermcap be stripping out aroma/flavor?
- Fermcap actually increases bitterness utilization.

Whole leave vs pellet maybe at certain points in the boil?
- I prefer pellets, this is an overlooked piece most people never take into consideration is the quality of your hops. They are certainly not equal, many shops have poor hops, remember we get the worst of the crop to begin with as pro brewers take the cream of the crop. I tend to order in bulk around harvest, vac sealer at home, and store in freezer. I tend to also open hops and use them in succession for recipes instead of using 2oz of 5 different varieties. When those run out open a few more bags and make recipes with those varieties.

Strong boil vs slow rolling?
- Strong boil

I would also recommend taking a look at your process. Oxygen uptake really dulls hoppy beers more so then any other style. Take a look at recipes that have 4-6oz hop stand additions, might even use half at flameout them chill to 160F and add the rest for a hop stand. Dry hops also 2-6oz per batch should be giving you great aroma.

Last thing is speed. Look at blogs like bertusbrewing, he's finishing primary ferments in 10 days even big beers, kegging, adding more dry hops for a 3-4 more days at room temp then carbonating/drinking by day 16. Many people on the forum recommend the 3 week primary but it's reducing all those great delicate aromas.

 

[Braufessor]

+1 to tschafer in regard to mash pH...... Regardless of flavor ion approaches, you need to make sure you are getting mash pH's that work with pale hoppy beers. Generally, I have been targeting 5.4. A little above or below keeps you in the ball park.

 

[hopsandhops]

I agree with most of the above

I use Bru'N water to estimate a mash PH around 5.4-5.45. Remember that Rahr malts are pre-acidified and that you should add 3 L when entering the grain bill in the spreadsheet

I've used ~180 sulfate/~80 chloride and ~150 chloride/~80 sulfate and both work well, they just produce different beers.

I prefer adding some late boil hops, not just whirlpool. I add roughly 50% of my IBU with additions from 20-2. The other 50% comes from a 60 minute. Say, 2-4 oz from 20-2 and then 4-10 oz in a 180* whirlpool. 4-6 oz in the DH.

I don't count any IBU from a 180* whirlpool

As long as you are using a lot of late hops, once you get past say 60 IBU, i find there's not much difference between 70 and 200 IBU in terms of bitterness.

I find gelatin reduces hop aroma

I'm in the 6-7.5% abv for IPA camp

I use pellets. I buy in bulk at harvest and vacuum seal and store in the freezer.

For bigger IPAs, a 50/50 mix of 2 row and MO works great. For lower abv, mostly 2 row with 5-10% vienna, and 3-5% 20-60L crystal can add some character. Using wheat instead of crystal can also add some sweetness without the typical crystal character.

Also agreed on speed. There's not much reason to go beyond a 10-12 day primary if you've aerated and pitched enough yeast.

 

[Soyben]

Are you a member of the local HB club? I believe they go by Mid State Brew Crew, I have seen them on facebook before.

I wouldn't play with the water until you know what you have and understand it better. I haven't done anything with mine and I am doing some pretty good IPA's now. I am about to get a profile done at Ward Labs and start experimenting with mine after I finish reading a book I recently got. My water comes from the Duck River (Lake Normandy) where yours comes from the Stone River which orginates in the same area so we should have fairly simular water. Hard water is generally good for hoppy beers.

 

[EyePeeA]

Here is the way to go for your basic American Double IPA:

For fermentables, focus on a clean base malt; you can even focus on rye
Wheat malt or other head retention malts: 0-6%
Light crystal malts: 0-6%
Dextrose: 0-6%

148-151 F mash temp.

5.2 to 5.4 mash pH. Look into using Gypsum and Lactic Acid for help with this.

Strong, vigorous boil for at least 60 minutes.

For an in your face Double IPA, a minimum of 1 oz. dryhops per 1 gallon beer. More can't hurt within reason.

Big whirlpool/flameout additions, though not as large as the dryhop.

Zero boil hops, which can add astringency. Use HopShot instead and add it at a full rolling boil. Don't worry about IBUs in general for these beers. The paper figure means nothing to the palate.

Get a clean yeast or a yeast that accentuates the hops, such as Vermont Ale Yeast, WLP001, WLP090, or Wyeast 1056. Make an adequate sized yeast starter 2-3 days before brewing!

Stay in the low to mid 60s for primary fermentation. When the gravity readings are in the teens (1.013-1.015 for example), up the temp to 68-70 F and add dry hops for 4-5 days.

 

[PartagasD4]

I use Bru'N water to estimate a mash PH around 5.4-5.45. Remember that Rahr malts are pre-acidified and that you should add 3 L when entering the grain bill in the spreadsheet


I've read something similar online in a few places, but this is not what I am experiencing. Has anyone ever verified this claim? I just bought a 50 lb sack of Rahr 2-row 3 months ago here is the link to the malt analysis pdf

https://bsgcraftbrewing.com/Resources%5CCraftBrewing%5CCOA%5CCOA_20150910_22438-10_TRCK%2029974_BSG_KASO_2P.pdf

If you open that .PDF at the bottom of the page there is pH info, now I am not claiming to know more than anyone here but it states.

pH: 5.84

Maybe this means something completely different than my take but
I did a small 12.5 gram/ 50ml distilled water mash and my reading after 15 minutes pH 5.83. This does not seem that the malt is pre-acidified.
The reason I am saying this is because I used similar advice from the web and missed my mash pH of 5.4 on my first use of this malt. It was 5.59 when I tested it at the 30 minute mark, which is still acceptable but I like to be closer than .2 pH off. I just ordered a better gram scale so I can do test mashes before I commit to larger brews

 

[losMythos]

I use Bru'N water to estimate a mash PH around 5.4-5.45.

Just curious about your target Mash PH being 5.4-5.45. What is your reasoning for wanting the higher end of the acceptable range. What benefits do you gain and where does that leave your Post boil PH?

 

[Hammy71]

Greetings all. My general brewing practices over the years have got better and more efficient. I'm producing more consistent with less faults than ever. The one thing I'm missing still is hitting the mark on my IPA's where they are aroma and flavor filled punches in the face. I thought maybe my hop tolerance was just increasing and senses getting numb, but I still get what I'm looking for in some commercial examples. Achieving bitterness isn't the problem, but the aroma and flavor components are lacking. As far as recipe design goes, I feel like I'm adding plenty of hops for bittering and should be enough late hop additions and dry hopping for aroma and flavor. I'm also adding less caramel malts and mashing lower than I ever did in the past.

I'm curious what are some of the techniques you all are using to get the most out of your hops in your IPA's.

Here are some things to get us thinking...

Are there certain ABV's you try to target?
Any malts you try to avoid?
Any special water treatments?
Could any additives like campden affect aroma/flavor?
Could anything like fermcap be stripping out aroma/flavor?
Whole leave vs pellet maybe at certain points in the boil?
Strong boil vs slow rolling?


just random thoughts... I'd love to hear people's thoughts or things they know to do that produces great IPA's every time.

I'll give you what works for me......

1. My IPAs are usually between 6.5% and 9%

2. Mostly all of them. My best IPAs are mostly 2 row. For me, the more variety of malts just takes away from the hops. If I do add something else it's very little and very light. Mash low, around 149 for 90 minutes....

3. I've never tested my well water but consider myself lucky. My beers come out fine.

4. No Camden tablets.

5. I never use Fermcap. I know some swear by them, but I ain't putting silicon (or silicone...)in my beers. I use a large kettle and large fermenters with blow offs....no need for the stuff.

6. I use exclusively pellet hops. Large dose of hops at 60 minutes to get 75% of your IBUs...then dump huge amounts in 15 minutes to flame out. A good rule of thumb is to at least match your final IBU with the OG of the beer. If your OG is 1.075...shoot for at least 75 IBUs and don't be afraid to go higher. Dry hop with more than you think. If you think an ounce will do....make it two. (Hey that rhymed....)

7. I always have a strong boil.

8. I'll add an 8th suggestion. Whirlpool your flame out hops until the temperature drops til around 200F. Then chill like crazy. This method and using Whirfloc has helped me make crystal clear beers. If I whirlpool for a set time and don't take heed of the temperature...chill haze.

This is what works for me. This method makes me awesome IPAs.... Your results may vary.

 

[hopsandhops]

I use Bru'N water to estimate a mash PH around 5.4-5.45. Remember that Rahr malts are pre-acidified and that you should add 3 L when entering the grain bill in the spreadsheet


I've read something similar online in a few places, but this is not what I am experiencing. Has anyone ever verified this claim? I just bought a 50 lb sack of Rahr 2-row 3 months ago here is the link to the malt analysis pdf

https://bsgcraftbrewing.com/Resources%5CCraftBrewing%5CCOA%5CCOA_20150910_22438-10_TRCK%2029974_BSG_KASO_2P.pdf

If you open that .PDF at the bottom of the page there is pH info, now I am not claiming to know more than anyone here but it states.

pH: 5.84

Maybe this means something completely different than my take but
I did a small 12.5 gram/ 50ml distilled water mash and my reading after 15 minutes pH 5.83. This does not seem that the malt is pre-acidified.
The reason I am saying this is because I used similar advice from the web and missed my mash pH of 5.4 on my first use of this malt. It was 5.59 when I tested it at the 30 minute mark, which is still acceptable but I like to be closer than .2 pH off. I just ordered a better gram scale so I can do test mashes before I commit to larger brews

I can't tell if this is spam or not.. sorry if it isn't...

There's a note about Rahr malts in the Bru'N water instructions, that's where the 3 L adjustment comes from. I've also researched online, (where the truth lives lol) and come to similar conclusions. I don't have a meter, so I'm at the mercy of the spreadsheet

 

[hopsandhops]

Just curious about your target Mash PH being 5.4-5.45. What is your reasoning for wanting the higher end of the acceptable range. What benefits do you gain and where does that leave your Post boil PH?

I was initially shooting for low to mid 5.3s and all of those beers had very disappointing hop character. Since moving into the 5.4s, my hoppy brews have been much better. As mentioned above, I don't have a meter, so I'm estimating. As a result, I also don't have a way to measure the post boil ph

 

[biestie]

Any malts you try to avoid?

I avoid crystal entirely. You don't need it. I just look to get a touch of malt character beyond the two row. A pils and biscuit combination is really nice, but you can go in virtually any direction. Victory, Munich, Vienna, wheat, rye... Use restraint, like I said just something to get just a bit beyond the 2 row. Mash low and use sugar to help dry it out if you need to. I shoot for 1.008 to 1.010.

The answer to the rest of your questions is probably... Meh... Doesn't really matter.

The biggest impact, beyond all others though, as some have mentioned, is a lot of late hopping and whirlpool additions. Depending on how much you're willing to spend on hops, shift some of the IBU contribution from the 60 minute addition, to inside of 20. That coupled with a huge addition in the whirlpool at 170F for 30 minutes (or if you can't whirlpool just a hopstand with some stirring every few minutes).

Add a big dry hop addition and you'll have kick ass IPA.

 

[Transamguy77]

I agree with all of what was already said but something not mentioned is dry hoping in the keg. I don't dry hop in primary anymore I just keg it and add hops in a muslin or paint strainer bag and put it right in there. Has a very fresh in your face hop aroma.

 

[losMythos]

I was initially shooting for low to mid 5.3s and all of those beers had very disappointing hop character. Since moving into the 5.4s, my hoppy brews have been much better. As mentioned above, I don't have a meter, so I'm estimating. As a result, I also don't have a way to measure the post boil ph

Right On. Yeah I'm always shooting for the low end 5.2 to try and get my Final beer PH in the mid 4s but wanted to try Mashing in different ranges but feared my post Boil PH would be higher in result... I'll have to just try it and see what happens.

 

[PartagasD4]

Just curious about your target Mash PH being 5.4-5.45. What is your reasoning for wanting the higher end of the acceptable range. What benefits do you gain and where does that leave your Post boil PH?

Actually the first two sentences of my post was supposed to be a quote from someone else's post and the quote function didn't work for some reason
damn newbies lol

 

[PartagasD4]

I can't tell if this is spam or not.. sorry if it isn't...

There's a note about Rahr malts in the Bru'N water instructions, that's where the 3 L adjustment comes from. I've also researched online, (where the truth lives lol) and come to similar conclusions. I don't have a meter, so I'm at the mercy of the spreadsheet

It's not spam, and yes I know I have the same spread sheet. I am going to take some questions over to the brew science forum and not derail the OP thread.

 

[hopsandhops]

It's not spam, and yes I know I have the same spread sheet. I am going to take some questions over to the brew science forum and not derail the OP thread.

My apologies. There's been some weird spam posts lately.

 

[johngg123]

Living in San Diego, land of IPA's, I've gotten to a point where I prefer my homebrew to the local bottle shop which is a game of roulette to see how long the thing has been on the shelf. I've also won ribbons at the SD County Fair for IPA so I know my tastes aren't wacko.

Here's my major success points:

Yep, the big hop dumps at 180 whirlpool and dry hops at 7 and 10 days (assuming fast fermentation.)

Dump a big starter of WLP001 to rip through the 148-152* mashed highly fermentable wort (read dry.) Follow a bertusbrewery type fermentation profile. 63* (24 hr), 65* (48 hr), 68*-70* there after.

(Begin Rant..)

Think of hops like wine grapes. There is an old saying that the winemaker's job is to not f*ck up the grapes (slightly rephrased.) I started winemaking before brewing and it has really made me love brewing because we work with so many commodities in brewing (e.g. grains, yeast, water.) However with an IPA you are showcasing hops, a crop where quality matters - like grapes. I've even heard famous brewers of IPA's (you can guess 'em) talking and about hop terroir.

And yes, the big brewers get the best hops but the difference between wine and beer is you can just add more hops!! :rockin: Trust me that you cannot add more crappy grapes to make better wine. But if your hops are from a great supplier then it doesn't matter that the brewer got a batch with 10% more aroma, just add 10% more whirlpool/dryhop. Homebrewers can beat pro brewers in two major areas: 1.) lack of consistency and 2.) lack of cost restrictions.

OK, so I said hop quality does matter and you add more to make it up. That being said, it doesn't matter how much stale catty LHBS simcoe you add, it's only going to get worse. Source quality hops. I just got some kickass 2014 mosaic (yes 2014) cheap and it's still amazing. Hops properly packaged and properly stored will last for years (i.e. 1 pound bags at a good online supplier.)

(...End Rant. )

Johnny G

 

[ultravista]

Great thread. Subscribing.

 

[EyePeeA]

Most don't know this, but the trick is really zero boil hops. Use a ton of C02 hop extract at full rolling boil and then nothing until whirlpool and dryhop. I'm talking 4-5 oz. pellet hops for the whirlpool and 6-8 oz. for the dryhop.

Since hops are reminiscent of delicate herbs like parsley, basil, cilantro, chervil, or even marijuana... You dont want to boil them for long or you kill the flavor and aroma. Boiling them really adds to the unpleasant bitterness and astringency you find in the majority of IPAs. You don't want that. You want a blast of flavor and aroma with some pleasant bitterness.

Additionally, yeast health, yeast practices, and temperatures are of the utmost importance. Never exceed say 65 F in the first week of fermentation for an American IPA with Cali or Vermont yeast. Patience is key. Your beer won't be ready to bottle until 2 to 3 weeks after you place it in the primary.

Water profile is also quite important. Test your water first, but more than likely, you will need to use gypsum and lactic acid to up the calcium and sulfate while decreasing the mash pH to about 5.2-5.4.

 

[johngg123]

I completely agree on the hop extract point. However the value proposition of using my extra CTZ ($10/lbs) at the rate of .75 oz @ 60min for total bittering is just too great. Especially with a monster hop bomb which will crush my budget, can't fork out the money for hop extract.

oh one last thing I forgot to mention that I have learned just recently. In my experience, if you make the perfect homebrew... The aroma should be huge but flavor IMHO takes a couple weeks to develop. IPA it will be "watery tasting" a week after kegging (brewday + 20 days.) Breweries have "bright tanks" for this reason. Good breweries with really good relationships with pubs will actually tell them to sit on a keg for X days until tapping. Give it two weeks in the keg to peak, then it's downhill from there.......

Johnny G

 

[EyePeeA]

I got 15 ml hop extract for $7, which is plenty for a bittering addition in a high gravity double IPA. Though you could go slightly higher.

12 oz. 2015 pellet hops were more than triple that price and used simply for whirlpool and dryhop. I get way more flavor and aroma that way without any of the harsh, astringent bitterness.

Plus, IMO you can't use too much Columbus because of the potency. It needs to be balanced with other hops.

 

[squaremile]

Two pieces to highlight besides the hop dosing, are water and co2. Oxygen is the natural enemy of hop aroma and flavor. Also dialing in water, as not sexy as it is, could be the biggest factor imo.

 

[Magnus314]

I use FWH, whirlpool, and dry hops only to get the most "Punch". A Double Whirlpool seems to work best, with some at flameout and more at 180-.

Boil and 45-5 minutes seems like a waste, with little flavor and under-utilized IBU's.

 

[NathPowe]

I've found that the best way to make good IPA is to make a bunch of batches of IPA and take really good brewing/tasting notes on each one. Experiment with all the tools/techniques available (dry/whirlpool/water adjustment/grains/etc.), but try not to change too many variables from batch batch. Make special note of the particularly good batches and of the ones that weren't great.

This may sound snarky, and I suppose there's a little sarcasm in there but at the same time it truly does work. Taste is subjective, ingredients/equipment vary, and there's no 'magic bullet' to hit the Ultimate Perfect IPA of Glory. However, if you practice and learn as you do so it's basically guaranteed you'll be making IPA you f**ing love after a while. Plus it's highly likely that, for the most part, the 'experiments' you create in the meantime will tasty pretty damn good as well. Just my $0.02.

Cheers and enjoy the brew.

 

[Braufessor]

I've found that the best way to make good IPA is to make a bunch of batches of IPA and take really good brewing/tasting notes on each one. Experiment with all the tools/techniques available (dry/whirlpool/water adjustment/grains/etc.), but try not to change too many variables from batch batch. Make special note of the particularly good batches and of the ones that weren't great.

This may sound snarky, and I suppose there's a little sarcasm in there but at the same time it truly does work. Taste is subjective, ingredients/equipment vary, and there's no 'magic bullet' to hit the Ultimate Perfect IPA of Glory. However, if you practice and learn as you do so it's basically guaranteed you'll be making IPA you f**ing love after a while. Plus it's highly likely that, for the most part, the 'experiments' you create in the meantime will tasty pretty damn good as well. Just my $0.02.

Cheers and enjoy the brew.

Absolutely....I think it is important for everyone to understand that any of these threads are starting points. It is unlikely anyone is going to take a recipe off of a forum and apply it to their own set up and make a truly great beer in one attempt. The good thing about these threads is it can give you a place to start that might save you (perhaps) dozens of your own test batches. However, in the end, you still need experiment in ways that refine recipes and strategies for your own set up and your own tastes.

I think people who try to brew a recipe once, time after time, going from one to the next "magic bullet" will always be disappointed and frustrated. If you really want an IPA you love - find a starting point, and keep refining it. 10-20-30 batches of the same beer with single changes from batch to batch - that is what gets you there.

The great thing about threads like this (and others) though is that it might only take you 10-20 batches to dial something in as opposed to 30-40 batches.

 

[PetVet]

FWIW, I like a dry, hop-forward IPA as well. ABV doesn't really matter to me; whether it's an IPA or a DIPA, I want the hops to pop.

In Omaha, we have some of the worst water so I won't use it. The pH of my water is 9 which is ridiculous.I buy bottled water and add to it if I have to.

I think pH is a big thing. Use the 5.4pH buffer in the mash and sparge if I have to.

+1 on the crystal malts. The only reason to have them, IMO, is for a little color. Crystal 10 is my favorite. I like to keep the IPA's simple in recipe like 2row, little Munich, some flaked oats and less than 4% crystal. I've dried them out with a little sugar and orange blossom honey, too.

I use pellets and mash hop with 2-3 oz then, more bittering additions (amount depends on the AA's) go in no more than 20 minutes left in the boil. Whirlpool with 2-3 oz then chill. My dry hopping schedule has changed as I use to dry hop at day 0 and day 7 (14 days total) in the secondary. Now, I do it at day 0 for 5-10 days and I have tasted a fresher, cleaner flavor/aroma as well as no grassy/vegetal flavors I got with all those pellets sitting on the beer. I secondary in corny kegs and use hop bags. The great thing about it is I purge with CO2 as oxygen can affect hop flavor and aroma. I put an airlock on it just in case.

I don't think the boil really affects hop flavor/aroma but, it does affect DMS removal. I always have a rolling boil.