Ascorbic Acid and Beer

[DocAnna]

Right. I was perhaps trying to be over cautious when buying it. I was concerned about oxygen contact when dry hopping, if fermentation had ceased. Even though I would always flush my fermenter with co2 afterwards, if that was the case. Are you aware of any negative effects of adding it during the dry hopping stage?

I routinely mix the vit C with the dry hops now and add them altogether. The 0.7g calculation is absolute worst case scenario and even a tenth of this should be enough in most cases. Adding it at the time of the dry hop additions is a bit of insurance really.

Anna

EDIT - link to the sciency bit Closed transfer and bottling - are they mutually exclusive?

 

[An Ankoù]

Aren't commercial hops supplied oxygen purged and vacuum packed? Wouldn't ordering the pack size to suit the recipe be a way forward? I see that CML do 50g packs as well as 10-25g "tea bags" enclosed in a foil which is CO2 flushed.
If I read a book like, for example, Alworth's Secrets of Master Brewers, where he apparently interviews brewers from traditional breweries in a number of countries, I don't see much if any reference to oxidation in his chats. The word doesn't even appear in the index. No doubt oxygen spoilage is awful, but do brewers of all styles need to be as observant as those making cloudy IPAs?
Looking at the amount of hops used in some of the historic recipes published by, for example, Ron Pattinson, it can be of the same order as those used in AIPAs, but there's little or no reference to oxidation and these beers are stored for ages until they're drinkable. The hops in the former are boiled, of course, while in the latter they're mostly added dry. What is it about dry hopping that makes the beer flavours so prone to degradation through oxidation?

 

[Cheshire Cat]

AA
I think you've hit the nail on the head, oxidation only seems to be an issue when dry hopping with loads of hops at ambient temperature. To quote Tommy Cooper "then don't do it".

 

[Agentgonzo]

Back in May, I did a few tests with a batch of saison. In one bottle (the one on the right) I put 1/32 teaspoon of ascorbic acid in the bottom of the bottle. The one on the left is a control. Both were then filled normally (no CO2 purge, no squeezing of the bottle, no mixing).

The photo is taken with a flash which makes them look a lot darker than they are (they are both a light blonde colour) and makes the difference look starker than it actually is, but they are easily different to look at.

I also used to have a bottle that I had filled normally, then squeezed the headspace out before sealing. It looked identical to the AA one after 3 months, but I had an emergency and needed to drink that one .

Both beers were stored in the house at room temperature over 5 months since May.

 

[DocAnna]

Back in May, I did a few tests with a batch of saison. In one bottle (the one on the right) I put 1/32 teaspoon of ascorbic acid in the bottom of the bottle. The one on the left is a control. Both were then filled normally (no CO2 purge, no squeezing of the bottle, no mixing).

The photo is taken with a flash which makes them look a lot darker than they are (they are both a light blonde colour) and makes the difference look starker than it actually is, but they are easily different to look at.

I also used to have a bottle that I had filled normally, then squeezed the headspace out before sealing. It looked identical to the AA one after 3 months, but I had an emergency and needed to drink that one .

Both beers were stored in the house at room temperature over 5 months since May.

View attachment 76356

This is really interesting to see. One of my unanswered questions about AA is whether it has a different taste threshold after oxidation, ie after it has consumed the oxygen that would otherwise oxidise the beer. I haven't been able to find anything on this in the literature, as an experiment I guess it would involve tasting maybe water samples that had been left open to the air which had different concentrations of AA added? But taste is pH dependent too, so would be different in beer than water...hmmm an interesting problem.

 

[Agentgonzo]

This is really interesting to see. One of my unanswered questions about AA is whether it has a different taste threshold after oxidation, ie after it has consumed the oxygen that would otherwise oxidise the beer. I haven't been able to find anything on this in the literature, as an experiment I guess it would involve tasting maybe water samples that had been left open to the air which had different concentrations of AA added? But taste is pH dependent too, so would be different in beer than water...hmmm an interesting problem.

Eventually when I open these, I'll do a side by side comparison and see if there is any noticeable difference in flavour. I'll try and get some opaque cups and do a triangle test to eliminate bias

 

[hoppyscotty]

AA
I think you've hit the nail on the head, oxidation only seems to be an issue when dry hopping with loads of hops at ambient temperature. To quote Tommy Cooper "then don't do it".

This seems to be the urban myth about oxidation but its not the whole story. A cask of Best Bitter down you'r'e local is only good for 3 - 5 days once tapped because as you pull the beer you're replacing the space with air and not CO2 and the beer becomes oxidised and undrinkable in that timeframe so malt forward beers with little or not late addition hops are just as susceptible to oxidation.

I'm anal about exposing beer to air and so far have not had any oxidised beers since I started taking measures to prevent exposure and now can hold a NEIPIA dry hopped at 16g/litre in a keg for 3 months or more without oxidation...or at lease sufficient oxidation to spoil the beer - probably more....I've not had one last that long!! In the past when I couldn't do totally closed transfers and bottled everything the handful of NEIPA's I did back then would be instantly oxidised in terms of the colour change, going from a nice bright yellow to a murky brown within days, and had to be drunk within a few weeks before the flavour was spoiled.

There is a video on YouTube from the Genus Brewing chaps talking about this and they say its best to add ascorbic acid into the mash. Don't understand the science behind it, but they had some logic behind it so worth a look. They also purported that crystal malts were a cause for oxidation too and that its not all about the hops.



If you're able to/willing get yourself a CO2 cylinder and the ability to close transfer and keg then keeping O2 out is not an issue and straight forward. Bottling becomes a bit more challenging, but I've had great results with one of those cheap as chips Ali Express counterflow bottle fillers.

 

[Agentgonzo]

This is really interesting to see. One of my unanswered questions about AA is whether it has a different taste threshold after oxidation, ie after it has consumed the oxygen that would otherwise oxidise the beer. I haven't been able to find anything on this in the literature, as an experiment I guess it would involve tasting maybe water samples that had been left open to the air which had different concentrations of AA added? But taste is pH dependent too, so would be different in beer than water...hmmm an interesting problem.

So, a result from my totally unscientific comparison. To reiterate, this is the same beer (saison) that was bottled differently. Both filled with my usual method of squirting beer into the bottle directly from the fermentor's tap. The right hand one was dosed with 1/32th of a TSP of ascorbic acid.

There is a notable difference in colour.

To taste, they were virtually identical, but not totally. If you had served them to me one after another in a pub, I would not have been able to notice the difference.
But sipping them side by side and looking for a difference, yes. You could just notice a difference. My wife described the AA beer as "marginally sweeter" or the non-AA beer as a bit more bitter. I would describe the non-AA beer as a fraction more tart. But with a fuller roundness to the flavour (which could be the oft -quoted cardboard flavours). But in no way did it taste "bad". Still a very delicious beer, but probably about 95% as delicious as it's AA-dosed sibling. I would attribute the difference in flavour and colour to oxidation.

These were bottled in may, and spent 8 months at room temperature (including the summer heatwave when it got into the high 30s).

 

[The Baron]

I have used for a while and now use it all the time now Agent. I first saw it on one of the American brewers who said they used it a couple of years ago and IMO it does preserve the beer better than without(non-scientific though)

 

[Agentgonzo]

I couldn't tell any flavours of ascorbic acid (though I don't really know that it tastes like anyway)

 

[Agentgonzo]

I have used for a while and now use it all the time now Agent. I first saw it on one of the American brewers who said they used it a couple of years ago and IMO it does preserve the beer better than without(non-scientific though)

Same here. I use it in all the brews that I don't forget it put it in

 

[The Baron]

I couldn't tell any flavours of ascorbic acid (though I don't really know that it tastes like anyway)

I think you need to use rather more than we would before any taste is evident.
I think I use 2 to 3 grams per Corny keg which is approx half a teaspoon

 

[Agentgonzo]

I think you need to use rather more than we would before any taste is evident.
I think I use 2 to 3 grams per Corny keg which is approx half a teaspoon

That was what @DocAnna was asking

 

[Agentgonzo]

I think you need to use rather more than we would before any taste is evident.
I think I use 2 to 3 grams per Corny keg which is approx half a teaspoon

Well I've just dosed my pale ale with some in preparation for bottling, and there was some crystals left on the half teaspoon measure. So I thought "what the hell" and licked it. So I now know what ascorbic acid tastes like. Basically slightly floury and slightly milder citric acid. Definitely no worries about tasting a small measure in 23L of beer