Ask The Brewmasters

Hi Andrew,

ALDC is pH sensitive and functions best at a pH of around 6.8 (see the ALDC manufacturer's tech sheet, also in the scientific lit). The pH is much higher at KO than at DH, which is likely why the enzyme functions better when added at KO. 

We recently ran an experiment and added ALDC at different time points (using the ALDC manufacturer's recommended dosage) and the ALDC was not effective when added at DH. One note about this experiment, is that we sensitized the assay by using a hop that we knew to exhibit hop creep (high diastatic activity) and we also added maltodextrin on the hot side to increase hop creep. So ALDC at DH may work sometimes, but not under particularly challenging conditions.

Here is the data from our study:

Nick, perhaps I'm reading the data wrong - it appears from the chart that the ug/L of the DH ALDC addition was much more effective than the KO addition?

Hi Andrew,

ALDC is pH sensitive and functions best at a pH of around 6.8 (see the ALDC manufacturer's tech sheet, also in the scientific lit). The pH is much higher at KO than at DH, which is likely why the enzyme functions better when added at KO. 

We recently ran an experiment and added ALDC at different time points (using the ALDC manufacturer's recommended dosage) and the ALDC was not effective when added at DH. One note about this experiment, is that we sensitized the assay by using a hop that we knew to exhibit hop creep (high diastatic activity) and we also added maltodextrin on the hot side to increase hop creep. So ALDC at DH may work sometimes, but not under particularly challenging conditions.

Here is the data from our study:

Nick, perhaps I'm reading the data wrong - it appears from the chart that the ug/L of the DH ALDC addition was much more effective than the KO addition?

------------------------------
Theo Muller
Urban Family Brewing Co
Seattle WA
(415) 652-6693
------------------------------


Original Message:
Sent: 03-05-2025 15:02
From: Nick Harris
Subject: ALDC usage beyond knockout

Hi Andrew,

ALDC is pH sensitive and functions best at a pH of around 6.8 (see the ALDC manufacturer's tech sheet, also in the scientific lit). The pH is much higher at KO than at DH, which is likely why the enzyme functions better when added at KO. 

We recently ran an experiment and added ALDC at different time points (using the ALDC manufacturer's recommended dosage) and the ALDC was not effective when added at DH. One note about this experiment, is that we sensitized the assay by using a hop that we knew to exhibit hop creep (high diastatic activity) and we also added maltodextrin on the hot side to increase hop creep. So ALDC at DH may work sometimes, but not under particularly challenging conditions.

Here is the data from our study:

------------------------------
Nick Harris
Co-Founder
Berkeley Yeast
San Leandro CA
(970) 274-1949

Hi Theo,

The data show that ALDC addition at knockout (grey line) works at keeping diacetyl low until the dry hop, but after dry hop, there is a big diacetyl spike. In the fermentation where ALDC is added at dry hop (black line), there is a still a big diacetyl spike and 4 days later, diacetyl is still above flavor threshold (you're right that it does look like the diacetyl may be dropping faster, though). Without any ALDC added (yellow line), diacetyl spikes at both the start of fermentation and at dry hop. Due to MBAA's policies around promotional content, I had to redact the green line label, which is the only condition where diacetyl stays below flavor threshold throughout the fermentation. 

Alan, we didn't test adding ALDC at multiple time points. One thing to keep in mind is that for our experiment, we did our best to sensitize the assay and create the worst case scenario for hop creep (using maltodextrin and a hefty hop charge of a hop that exhibits high diastatic activity). Under these conditions, we still see a big diacetyl spike when adding ALDC at dry hop. In other recipes, the spike may be less (as indicated by your data). 

Cheers,

Nick

Nick, perhaps I'm reading the data wrong - it appears from the chart that the ug/L of the DH ALDC addition was much more effective than the KO addition?

Hi Andrew,

ALDC is pH sensitive and functions best at a pH of around 6.8 (see the ALDC manufacturer's tech sheet, also in the scientific lit). The pH is much higher at KO than at DH, which is likely why the enzyme functions better when added at KO. 

We recently ran an experiment and added ALDC at different time points (using the ALDC manufacturer's recommended dosage) and the ALDC was not effective when added at DH. One note about this experiment, is that we sensitized the assay by using a hop that we knew to exhibit hop creep (high diastatic activity) and we also added maltodextrin on the hot side to increase hop creep. So ALDC at DH may work sometimes, but not under particularly challenging conditions.

Here is the data from our study:

Lots of great information in this thread already!

Full disclosure, we are an ALDC manufacturer, but I will only add data to add context and correct a couple things that have been brought up.

Directly relating to the original question, we adjusted our recommendations a few years back to also include an optional dry hopping addition. We've similarly recommended a secondary addition for fruited beers for the same reason.

Nick and Joel are correct that some ALDC on the market appears particularly sensitive to pH, and that the optimum is around 6.8. Mike's method of a smaller dose with each dry hop makes good sense given that the amount of precursors that arise from dry hopping is smaller than the amount that forms during normal fermentation, though for particularly large hop additions you may still with to split the dosing evenly between to account for the reduced activity at the lower pH, as Alex suggests.

However, data from our lab shows that at least our ALDC is not quite so precious as one might think (I don't have any data on other manufacturers products, so I can't make a broader claim). At a finished pH of 4.2, the relative activity is still around 60% of the optimum, meaning it will stay in the beer and be effective. The residual activity is even better (80%+) at pH of 4 or above (though that may not be as relevant - residual activity is when the pH drops to a given level, then returns to the optimum of 6.8).

From this, most sour beers are not good candidates for dry hop dosing of ALDC.

Per Nick's experiment, we do recommend an addition both at knockout at dry hop for particularly challenging brews - Nick, correct me if I'm wrong, but it looks like the testing was either knockout or dry hop addition, but not both?

I ask because the knockout addition should have activity that the dry hopping addition would be supplementing - just as a slight correction to Joel's comment, below is our data for a generic dry hopped pale ale that had 3g/hl of ALDC added at knockout. This does show that the dose applied at knockout will still be somewhat effective, so long as the pH does not drop too far below 4.0 prior to that during fermentation:

Also, as Mike noted, ALDC will only help with diacetyl, not alcohol production due to hop creep. All that said, Alex is 100% right that running a few trials to optimize the additions to your beers and process is the way to go!

Thanks all for the feedback and data!  I will start working toward a knockout + dry hop addition and trialing dosage rates.

Lots of great information in this thread already!

Full disclosure, we are an ALDC manufacturer, but I will only add data to add context and correct a couple things that have been brought up.

Directly relating to the original question, we adjusted our recommendations a few years back to also include an optional dry hopping addition. We've similarly recommended a secondary addition for fruited beers for the same reason.

Nick and Joel are correct that some ALDC on the market appears particularly sensitive to pH, and that the optimum is around 6.8. Mike's method of a smaller dose with each dry hop makes good sense given that the amount of precursors that arise from dry hopping is smaller than the amount that forms during normal fermentation, though for particularly large hop additions you may still with to split the dosing evenly between to account for the reduced activity at the lower pH, as Alex suggests.

However, data from our lab shows that at least our ALDC is not quite so precious as one might think (I don't have any data on other manufacturers products, so I can't make a broader claim). At a finished pH of 4.2, the relative activity is still around 60% of the optimum, meaning it will stay in the beer and be effective. The residual activity is even better (80%+) at pH of 4 or above (though that may not be as relevant - residual activity is when the pH drops to a given level, then returns to the optimum of 6.8).

From this, most sour beers are not good candidates for dry hop dosing of ALDC.

Per Nick's experiment, we do recommend an addition both at knockout at dry hop for particularly challenging brews - Nick, correct me if I'm wrong, but it looks like the testing was either knockout or dry hop addition, but not both?

I ask because the knockout addition should have activity that the dry hopping addition would be supplementing - just as a slight correction to Joel's comment, below is our data for a generic dry hopped pale ale that had 3g/hl of ALDC added at knockout. This does show that the dose applied at knockout will still be somewhat effective, so long as the pH does not drop too far below 4.0 prior to that during fermentation:

Also, as Mike noted, ALDC will only help with diacetyl, not alcohol production due to hop creep. All that said, Alex is 100% right that running a few trials to optimize the additions to your beers and process is the way to go!