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Lactate Taste Threshold Experiment

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Kaiser

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Last weekend I did a yeast handling presentation to Brew Free Or Die club members and I took the opportunity to conduct a lactate taste threshold experiment with 8 club members. While it had little to do with the topic of the technical session it is a subject where I wanted to do some experimentation for quite some time.

Acidulated malt and 88% lactic acid are very popular acids for mash pH correction but since lactic acid has a rather distinct taste the question that is on many brewer’s minds is: “How much lactic acid is too much“.

Since in most cases lactic acid is only added to counteract water alkalinity and bring the mash pH into the desirable range of 5.3-5.5 it can be assumed that the added lactic acid will not lead to a lower than normal beer pH. In other words, we don’t have to worry about beers that taste sour. But we do have to worry about the characteristic taste of lactate. Lactate is what’s left when lactic acid gives up its proton to neutralize a base or contribute to pH changes.

The experiment was designed such that the acidity of the lactic acid was neutralized with slaked lime. While that also adds calcium in addition to the lactate it matches brewing reality where highly alkaline waters oftentimes come with high calcium levels. I had the choice between calcium (from slaked lime) or sodium (from sodium hydroxide). Both calcium lactate and sodium lactate tasted very similar in water which shows that sodium doesn’t necessarily lead to a salty taste. I decided to go with calcium lactate since calcium is generally the dominant cation in alkaline waters.

I was very surprised to see how many of the tasters struggled with identifying the flavor in the 4 sets of samples they were given (water, Bud Light, Budweiser and Sierra Nevada Torpedo Ale). Even levels as high 1200 mg/l, which amounts to a whopping 23% acidulated malt, were not correctly identified by some tasters. Below is a link to a more formal write-up of the experiment and those interested can go ahead and check my numbers.

Here is a chart that shows for each taster the highest lactate level that was identified as tasting like the control:



After having done this experiment and having tasted samples with added lactate myself I think that a safe upper limit of 400 mg/l lactate or 7% acidulated malt is reasonable with the assumption that the mash and beer pH are at acceptable levels. While 7% is higher than the 5% that is currently seen as the safe upper limit for acidulated malt use it should be noted that there might be other benefits to reducing the amount of minerals in a given water before acidulated malt is used to neutralize the remaining alkalinity.

A formal write-up of the experiment can be found on the braukaiser.com wiki: Lactate Taste Threshold Experiment
 

TyTanium

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Great writeup, as usual! Thanks for posting.

Can you translate the 7% acid malt threshold into mL/gallon of 88% lactic acid?
 
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Kaiser

Kaiser

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Great writeup, as usual! Thanks for posting.

Can you translate the 7% acid malt threshold into mL/gallon of 88% lactic acid?
That depends on the mash thickness. For a 4 l/kg mash (about 2 qt/lb) we are talking about ~2 ml/gal to the mash water.

But if that much acid is needed in the mash, sparge water acidification may be needed as well.

If I work back from the 400 mg/l number, assume that lactic acid is added to all brewing water and that there is about 15% evaporation in the kettle I arrive at an amount of 1.2 ml/gal.

Kai
 

TyTanium

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That depends on the mash thickness. For a 4 l/kg mash (about 2 qt/lb) we are talking about ~2 ml/gal to the mash water.

But if that much acid is needed in the mash, sparge water acidification may be needed as well.

If I work back from the 400 mg/l number, assume that lactic acid is added to all brewing water and that there is about 15% evaporation in the kettle I arrive at an amount of 1.2 ml/gal.

Kai
Thanks. That rings true with other anecdotal numbers I've seen...~5mL for a normal 5g batch as a threshold.
 

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Kaiser

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eric19312

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TyTanium said:
Thanks. That rings true with other anecdotal numbers I've seen...~5mL for a normal 5g batch as a threshold.
I normally use about 8 to 8.5 gal water in a nominal 5 gal batch counting mash and sparge. I think that puts threshold at 9.6 mL for the batch.
 

eric19312

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Question, were any of the tasters certified tasting judges?

Small data set but did you see any reason to believe the more experienced tasters in your panel were able to detect lower threshold levels?

I apologize if these were addressed in the complete write up. Thanks for posting the experiment!
 
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Kaiser

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Question, were any of the tasters certified tasting judges?

Small data set but did you see any reason to believe the more experienced tasters in your panel were able to detect lower threshold levels?

I apologize if these were addressed in the complete write up. Thanks for posting the experiment!
I know there were BJCP judges, but let me follow up and I think i would also be fair to call out the panelists that were certified.

Kai
 

BrewinHooligan

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Thanks for this write-up Kai! I am planning a Belgian Tripel and was having issues with my pH and water adjustments. According to the Bru'n water spreadsheet I would need 6% acid malt to bring pH to 5.4 and I was worried about off flavors. Would you advise possibly not trying to mimic a specific water source to keep the pH in range with less acid malt, or brew with 6% acid malt in the grist?
 
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Kaiser

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I'd be careful with BW and acidulated malt. It doesn't seem to implement it correctly. Run your water and recipe through this one http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/, just for a 2nd opinion. Maybe one day I write an import function for the various water spreadsheets out there. Recently a fellow club member mentioned to me that BW wanted him to add 10% acid malt which was rather excessive.

You should see a pH drop of about 0.1 pH units for every % of acidulated malt used.
 

BrewinHooligan

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I'd be careful with BW and acidulated malt. It doesn't seem to implement it correctly. Run your water and recipe through this one http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/, just for a 2nd opinion. Maybe one day I write an import function for the various water spreadsheets out there. Recently a fellow club member mentioned to me that BW wanted him to add 10% acid malt which was rather excessive.

You should see a pH drop of about 0.1 pH units for every % of acidulated malt used.
Great to know! I will certainly check out that calculator, 6% accumulated malt only dropped me around .3 pH if I remember correctly and thought that was excessive leading me to some searching and your post. Thank you again, your contributions here have had a huge impact on the quality of beer I make.
 

BrewinHooligan

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Update, re-ran my figures through your calculator Kai and according to that only half the Acidulated Malt that BW stated I needed would be needed to drop the pH from 5.7 to 5.4. Thank you again
 
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