Expired dry Yeast

[hector]

Hi there !

Would using an expired dry ale yeast lead to "Ethyl Acetate" off-flavor ?!

I already know that there are three Causes for this off-flavor :

1- Oxidation of Alcohol

2- Using Non-food grade plastic equipment

3- Infection

I do my best against all these , but my Beer still has nail polish remover smell .

Hector

 

[Captain Damage]

Try keeping your fermentation temperature down and pitching plenty of healthy yeast. Expired yeast is of dubious health and viability. Meaning that you may be pitching far less live yeast than you think, and what's left may be in poor health. Dry yeast is best if rehydrated before pitching. To keep your fermentation temp down, one way is to put it in a big bucket (old fashioned washtub size), or tupperware tray and add ice and water. Ferment in the mid 60Fs. Also, be wary of pitching too warm. Many people pitch as soon as their wort gets down to the mid 80Fs. Pitch after your beer gets below 70F.

 

[hector]

Try keeping your fermentation temperature down and pitching plenty of healthy yeast....

I kept the fermentation temperature at 62 F and I always re-hydrate the dry yeast before pitching , using pre-boiled spring water and I don't pitch too warm .

The Lag time is always about 6 Hours , so I think the yeasties are still healthy .

Do you think that it still can produce that off-flavor ?

Hector

 

[Hopper5000]

how expired are we talking? dry yeast has pretty good viability long after it's expiration date.

 

[hector]

dry yeast has pretty good viability long after it's expiration date.

Yes .

As I said , the 6 Hour-Lag-Time shows that they are still viable , doesn't it ?

So , the Cause of that off-flavor should be something else .

Hector

 

[fixitoscar]

Hot fermentation in the first 48 hrs and over aerating are the 2 reasons that pop into my head.
how do you keep your temps down?
over aerating is only possible with pure oxygen. Are you are using o2? If so how much are you using?

 

[hector]

Hot fermentation in the first 48 hrs and over aerating are the 2 reasons that pop into my head.
how do you keep your temps down?

As far as I know , Hot fermentation leads to producing fusel Alcohols .

I keep the glass Carboy in a Cooler filled with water and frozen bottled water .

In order to aerate the wort , I shake the Carboy vigorously for 1-2 minutes after cooling and

pouring the wort from the Pot into it .

Hector

 

[fixitoscar]

So how many batches ago did you make beer without this flavor in it? Was there any changes that happened at that time?
How are you cleaning and sanitizing? and how many brews do you have on your plastics (buckets tubing) ?

 

[Hopper5000]

what was your recipe too? that flavor you are describing sounds like fusel alcohol. Again, how old of a yeast packet are we talking. Do you have a thermometer on your carboy. Even if you are using ice packs if the ambient temp is super high where you are fermenting then it could still be going hot. Do you pitch your yeast warm?

 

[hector]

So how many batches ago did you make beer without this flavor in it? Was there any changes that happened at that time?
How are you cleaning and sanitizing? and how many brews do you have on your plastics (buckets tubing) ?

I had that off-flavor in all my previous batches which were brewed using plastic Jugs and Non-food grade vinyl tube . Therefore , I used a glass carboy and food-grade vinyl tube by my recent batch , but the off-flavor is still detectable .

I use dish detergent for cleaning the carboy and rinse well with warm water afterwards , then I sanitize everything very carefully with Iodophore which is made by diluting "Povidone Iodine 10%" with water
(1.25 ml per liter of water ) .

Hector

 

[masterfool101]

OK, you get Ethyl Acetate for the following reasons:

1) Lack of oxygen in early fermentation.

2) Temperature control during the first 48 hours of fermentation - higher temperature leads to more ester (and thus Ethyl Acetate) production

3) Yeast strain. Some strains produce more esters. Belgian strains are known for it.

4) Yeast pitching rates compared to gravity. Lower pitching rates result in MORE esters.

So, to look at your issue:

The best guess would be that you either aerate properly. Since you said you rehydrated the yeast, I doubt they were unhealthy. Pitching rates COULD be an issue, given that the yeast is expired . . . but given that a typical dry yeast packet contains upwards of 10x the yeast cells of a smack pack, you wouldn't think this would be an issue.

You say you control the temp in a water bath . . . and keep it at 62, so that shouldn't be an issue.

The final question, then, becomes "what strain are you using" . . . some strains are known to produce more esters . . . of which Ethyl Acetate is one of them.

 

[hector]

what was your recipe too? that flavor you are describing sounds like fusel alcohol. Again, how old of a yeast packet are we talking. Do you have a thermometer on your carboy. Even if you are using ice packs if the ambient temp is super high where you are fermenting then it could still be going hot. Do you pitch your yeast warm?

My recipe is very simple ( Partial Mash ) .

I used 2-row pale malt , Crystal malt and light DME .

One Week Primary and two Weeks Secondary , then primed using Dextrose and Dextrine .

The bottles were kept at 70-72 F for 5 Weeks .

I brew small batches ( 3 liters ) because I live in an Apartment . It gives me 9 pet bottles (330 ml each ) . The carboy is not so big and I don't think that the Beer gets too warm by the time of fermenting .

By my previous batches , I kept the ambient temperature at 66-67 F and they had the off-flavor .

The ambient temperature by my recent batch was kept at 60-61 F and the off-flavor is still detectable .

The expiration date of the dry yeast is 10-2012 and I never pitch warm .

One thing I'd like to mention is that I always taste a little of the Beer by the time of racking to

the Secondary and bottling , but that off-flavor was NOT detectable then .

Hector

 

[hector]

The final question, then, becomes "what strain are you using" . . . some strains are known to produce more esters . . . of which Ethyl Acetate is one of them.

In fact , I studied Chemistry and I'm familiar with such things .

I used "Safale S-04" and I know that it's a British strain , but there must be some difference in Ester production at 67 and 60 F .

Hector

 

[masterfool101]

In fact , I studied Chemistry and I'm familiar with such things .

I used "Safale S-04" and I know that it's a British strain , but there must be some difference in Ester production at 67 and 60 F .

Hector

Of course there is. . . but I was noting that you said you kept it pretty constant at 62, which is right in the proper range for S-04. I've never had an Ethyl Acetate problem with S-04, but I've only used it twice.

How do you aerate your wort?

 

[hector]

How do you aerate your wort?

I shake the Carboy vigorously for 1-2 minutes after cooling and

pouring the wort from the Pot into it .

Hector

 

[masterfool101]

How much headspace in the carboy when you do this? Remember, when you're in a carboy, you have limited headspace, and thus limited oxygen. Consider pouring the wort back and forth a few times between the pot and a bucket. Alternately, siphon the wort while using an aerator on the end of the tube (fans out the wort so it takes on oxygen).

Not saying this is the problem, but it could be a factor.

 

[hector]

How much headspace in the carboy when you do this?

There is 0.35-0.4 Gallon headspace in the Primary Carboy .

As I said before , the Lag time is about 6 Hours .

Do you think with such a short Lag time , there should be something wrong with aeration and

pitching rate ?!

Hector

 

[masterfool101]

It doesn't sound likely, but given your problem, it's the only thing I can think of. Short of being there myself, and seeing what you're doing, I can't think of anything else that would cause Ethyl Acetate at the levels you're describing.