Improper mash draining, off flavor?

[DapperD]

I'm trying to figure out where I'm getting this very slight sour off flavor from. I'm now re-reading Palmers book and finding little techniques I've previously missed. So to my question...

Could not putting my drain line under the surf, allowing the wort to splash into the boil pot, cause my off flavor?

In reading his book, Palmer states this can cause oxidation but I'm really not sure what type of flavor that would result with. The flavor seems to somewhat taper off after bottle conditioning. This is something I don't recall when doing extract kits.

Well any thoughts/suggestions are appreciated!

 

[dyqik]

The effect you are talking about is "Hot Side Aeration". Plenty of people think that it's been overdone as an effect on the home brew scale, but it is generally viewed as important on commercial scales. And plenty of home brewers will tell you to avoid it at all costs.

Since it's very easy to avoid potential HSA from splashing into the kettle - just let your hose dangle into the bottom of the kettle, or fill through the drain valve - I can't see any reason not to take that step. Other more extreme steps to avoid HSA may not be warranted though, unless you directly identify that as the problem.

 

[kh54s10]

I have always drained the tun to the BK through a short piece of tubing (valve wide open) so the wort is dropping a foot or more into the kettle. I have not had any issues. I am one that think hot side aeration is not a concern in home brewing.

IMO the problem lies elsewhere.

Sour off flavors are often described when people are tasting fusel alcohols. These are created by fermenting at temperatures that are too high for the yeast used.

Do you have good fermentation temperature control?

 

[Foosier]

Agree with kh54s10. If you are dealing with "off flavors" the number one place to look first is your fermentation temperature control. Lots of opportunities for issues there. If you are doing that right, then you might then look to be sure you are mashing at the right PH and temperature as getting that wrong can lead to other off flavor type issues.

HSA is a myth at our scale. When you boil you drive off the O2. When the boil is done, you then need to aerate to feed the yeast.

 

[RM-MN]

Some people perceive acetaldehyde as sour while others will say green apples or fresh cut pumpkin. Acetaldehyde is an intermediate product of fermentation and if given the right conditions the yeast will break it down further to make alcohol. Try keeping the fermentation temperature down near the bottom end of the yeast's preferred temperature range for the first 3 to 7 days, then let it rise to room temp to help the yeast digest this and other intermediate products.

 

[DapperD]

Thanks for all the great info guys!

As far as fermentation temps, the last few months my closet has been between 62°-66°. I have a 24hr hi/low thermometer in the room. This encompasses my last 3 or 4 batches.

Perhaps I'm pitching with the wort temp too high. I'll check my wort and starter temps more closely prior to pitching to make sure they's no delta between the 2. Unfortunately I don't have a ferment fridge to better control the temps yet, but if this continues it might be my next investment.

 

[TheHappyHopper]

I'm trying to figure out where I'm getting this very slight sour off flavor from. I'm now re-reading Palmers book and finding little techniques I've previously missed. So to my question...

Could not putting my drain line under the surf, allowing the wort to splash into the boil pot, cause my off flavor?

In reading his book, Palmer states this can cause oxidation but I'm really not sure what type of flavor that would result with. The flavor seems to somewhat taper off after bottle conditioning. This is something I don't recall when doing extract kits.

Well any thoughts/suggestions are appreciated!

That's crazy - My last couple batches I have noticed the same exact thing - kind of a harsh aftertaste that tends to mellow out after awhile (4-5+ weeks in the bottle). As I was driving in to work this morning I had the same thought, that I might be oxidizing my beer when I drain it from the mash tun. Glad I found your post before I posted an identical question

As others have mentioned, I am going to add a piece of tubing from the spigot on my mash tun when I drain it to the kettle so I don't have any splashing going on. I'm not sure if this is actually what is causing my problem, but I figure I might as well take one more variable out of the picture.

 

[kh54s10]

That's crazy - My last couple batches I have noticed the same exact thing - kind of a harsh aftertaste that tends to mellow out after awhile (4-5+ weeks in the bottle). As I was driving in to work this morning I had the same thought, that I might be oxidizing my beer when I drain it from the mash tun. Glad I found your post before I posted an identical question

As others have mentioned, I am going to add a piece of tubing from the spigot on my mash tun when I drain it to the kettle so I don't have any splashing going on. I'm not sure if this is actually what is causing my problem, but I figure I might as well take one more variable out of the picture.

If this works let us know since hot side aeration is becoming considered by most a non issue in home brewing. As I stated earlier, IMO - look elsewhere for your problems.

I am not saying not to try it though.

 

[dyqik]

Agree with kh54s10. If you are dealing with "off flavors" the number one place to look first is your fermentation temperature control. Lots of opportunities for issues there. If you are doing that right, then you might then look to be sure you are mashing at the right PH and temperature as getting that wrong can lead to other off flavor type issues.

HSA is a myth at our scale. When you boil you drive off the O2. When the boil is done, you then need to aerate to feed the yeast.

However, the boil can't drive off O2 that has already reacted and oxidized something in the kettle. Now, on the home brew scale we probably don't get much oxidation and we can turn around from runoff to boiling fairly quickly, so any off-tastes from it are probably below most people's thresholds of detection, making it a non-issue for most people. That doesn't mean that the entire thing is a myth though. Bubbling pure O2 through your first runnings would definitely cause a problem... Splashing into the kettle _might_ be enough to cause an issue if you take a long time to runoff and sparge and to get to a boil (which I think might be the main difference between commercial and homebrew scales here). Also, some people are more sensitive to certain off-tastes than others. For the cost of a couple of feet of hose, you might as well avoid splashing the wort.

 

[TheHappyHopper]

For the cost of a couple of feet of hose, you might as well avoid splashing the wort.

My thoughts exactly - it might help, but even if it isn't the cause, I have eliminated one more variable.

 

[bragona71]

Thanks for all the great info guys!

As far as fermentation temps, the last few months my closet has been between 62°-66°. I have a 24hr hi/low thermometer in the room. This encompasses my last 3 or 4 batches.

Perhaps I'm pitching with the wort temp too high. I'll check my wort and starter temps more closely prior to pitching to make sure they's no delta between the 2. Unfortunately I don't have a ferment fridge to better control the temps yet, but if this continues it might be my next investment.

You don't need expensive equipment to regulate temps.

I also use my closet but I wrap my fermenter in a winter jacket with a heating pad in the winter and summer a swamp cooler..You can also run swamp cooler in winter with a fish tank heater. inexpensive and effective. eventually building a ferm chamber but I have other priorities till then

I have consistant ferm temp using this method.. I have also have seen at LHBS a pad to set ferm on that regulates temp. IDK how effective those are

 

[dyqik]

I'm currently fermenting in a 50F basement, using a 20W seed germinating mat and a moving blanket wrapped around the fermenter, controlled by an STC-1000. Total cost about $70, and easily able to maintain 1 degree accuracy within 55-70F.

 

[Foosier]

However, the boil can't drive off O2 that has already reacted and oxidized something in the kettle. Now, on the home brew scale we probably don't get much oxidation and we can turn around from runoff to boiling fairly quickly, so any off-tastes from it are probably below most people's thresholds of detection, making it a non-issue for most people. That doesn't mean that the entire thing is a myth though. Bubbling pure O2 through your first runnings would definitely cause a problem... Splashing into the kettle _might_ be enough to cause an issue if you take a long time to runoff and sparge and to get to a boil (which I think might be the main difference between commercial and homebrew scales here). Also, some people are more sensitive to certain off-tastes than others. For the cost of a couple of feet of hose, you might as well avoid splashing the wort.

I agree with you here. Especially where we can eliminate a small variable for a very low cost. If you can do that, then I say go for it.

My primary issue with the OP's post is that he is looking at HSA as the possible culprit for this flavor. I agree that some people have much more perceptive taste thesholds than others. Some people will be able to tell the difference or perceive an issue which can be attributed to HSA. However, I would argue strongly to nail down the major causes of off-flavors (mash temp, mash PH, fermentation temps) before trying to get into these far more difficult to nail down causes for off flavors.

While 62-66 ambient is within the desired range for most of the ale yeasts we use, we know fermentation is an exothermic reaction and an active ferment can increase temps up to 10 degrees in the fermenter. So if the room temp was 66 and you got a 10 degree increase you'd be looking at a 76 degree ferment during the peak which is definitely high enough for off flavors. Even if the temp increase was only 5 degrees you would be at 71 and on the high side of the yeasts happy zone.

For me, I like to keep ambient in my chamber around 58-62 tops for the first 72 hours of fermentation. I let the temps revert to ambient (low 60's in my basement) after that. This ensures the yeast works clean during the most active phase of fermentation.

 

[TungstenBeer]

What's your sparge technique? Was this a big beer? Do you measure pH or take gravity readings of the last runnings?

If you think it's a mash issue, I'm wondering if it's astringency from husk tannins. Just a thought - might not be the right one.

 

[DapperD]

While 62-66 ambient is within the desired range for most of the ale yeasts we use, we know fermentation is an exothermic reaction and an active ferment can increase temps up to 10 degrees in the fermenter. So if the room temp was 66 and you got a 10 degree increase you'd be looking at a 76 degree ferment during the peak which is definitely high enough for off flavors. Even if the temp increase was only 5 degrees you would be at 71 and on the high side of the yeasts happy zone.



For me, I like to keep ambient in my chamber around 58-62 tops for the first 72 hours of fermentation. I let the temps revert to ambient (low 60's in my basement) after that. This ensures the yeast works clean during the most active phase of fermentation.

I will defiantly keep this in mind. Unfortunately my closet under the stairs has no electrical outlets so running power isn't an option (heaters/swamp cooler/AC, ect).

I have a ton of tubing so there's no problem at all adding additional length.

Funny thing is I bottled my first smash last night and the flavor was awesome, I didn't detect any off flavor what so ever. But moving forward I'll pay more attention to the fermentation temperature.

Thanks for all the tips!