Using Lactose for Sweetening

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An Ankoù

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I've just been looking at the Milk Stout recipe posted by @foxy (https://www.thehomebrewforum.co.uk/threads/what-did-you-brew-today.64550/post-1270962) and I'm wondering about the best time to add lactose to sweeten the beer. This is my thinking:
When we add sucrose to a boil for whatever reason, the sucrose will be hydrolised to some extent, depending on the pH and the length of time it is boiled, into its constituent monosaccharides. But since all three sugars are fermentable, we're not over-concerned about how much of the sugar has been converted. Does the same thing happen with lactose? Is it hydrolised into glucose and galactose by boiling it in a acidified solution? If so, then is galactose fermentable by beer yeasts? I wonder if it might not be better to add the lactose after the boil to get the best sweetening effect from it.
Of course, all my suppositions might be a load of old nonsense, i which case it wouldn't matter.
 
I've just been looking at the Milk Stout recipe posted by @foxy (https://www.thehomebrewforum.co.uk/threads/what-did-you-brew-today.64550/post-1270962) and I'm wondering about the best time to add lactose to sweeten the beer. This is my thinking:
When we add sucrose to a boil for whatever reason, the sucrose will be hydrolised to some extent, depending on the pH and the length of time it is boiled, into its constituent monosaccharides. But since all three sugars are fermentable, we're not over-concerned about how much of the sugar has been converted. Does the same thing happen with lactose? Is it hydrolised into glucose and galactose by boiling it in a acidified solution? If so, then is galactose fermentable by beer yeasts? I wonder if it might not be better to add the lactose after the boil to get the best sweetening effect from it.
Of course, all my suppositions might be a load of old nonsense, i which case it wouldn't matter.
I read this article about using lactose in brewing the night before I brewed.
https://byo.com/article/brewing-wit...iness and boosts,is desirable in some recipes.
 
One bit of advice do add the Lactose very carefully if using in the FV or at kegging as it will nucleate with the co2 and you can get a gusher.
Do not ask me how I know that:laugh8:
 
In the last paragraph, the writer says "all our lactose addition are done in the boil", but he doesn't say when in the boil. Sucrose hydrolysis is gradual and I don't know if lactose is even hydrolysed in the same way. I think that last point is really my question.
But the proof is in the pudding. Does lactose boiled for 15 minutes still add perceptible sweetness and mouthfeel?
 
One bit of advice do add the Lactose very carefully if using in the FV or at kegging as it will nucleate with the co2 and you can get a gusher.
Do not ask me how I know that:laugh8:
I presume it's not readily soluble, then, which is why it;s added to the boil.
 
Hi AA I am sure Foxy will answer and clarify but he may not be on till later maybe because of the time difference.
Ps it is not easy to mix in as you said it is like DME it needs to be stirred in well.
I usually use Lactose to backsweeten beers like fruit beers so I generally add to the keg once I have worked out how much to sweeten for my taste first. I dissolve in hot water now before adding
 
I don’t know the Machanics of the compounds but I add it in the last couple of minutes of the boil when doing milk stouts and they always taste great. I scoop some wort out in a jug and pour in the lactose powder and mix, then just pour back in the kettle. I think mixing in hot wort is just easier to dissolve than a cold mix in to the FV
 
Why not drop a note to the institute of food science and technology (ifst)
They will give you chapter and verse on any enzyme and it's reactions, compositions and usage in food preparation and consumption
 
In the last paragraph, the writer says "all our lactose addition are done in the boil", but he doesn't say when in the boil. Sucrose hydrolysis is gradual and I don't know if lactose is even hydrolysed in the same way. I think that last point is really my question.
But the proof is in the pudding. Does lactose boiled for 15 minutes still add perceptible sweetness and mouthfeel?
I can answer that now my milk stout has finished fermenting, going into the fermenter it tasted sweet but at the end of fermentation there is still some sweetness very full creamy mouth feel but didn't hit the final gravity predicted.
Predicted FG 1,014 from an OG of 1,o54 my OG was 1,056, and FG 1,024. So I have to put it down to the lactose, only because I have read other threads on Milk Stout and brewers facing higher-than-expected FG seems common.
One bit of advice do add the Lactose very carefully if using in the FV or at kegging as it will nucleate with the co2 and you can get a gusher.
Do not ask me how I know that:laugh8:
I am thinking of adding to the fermenter if I brew it again but it won't solve the problem, and I also read adding it to a fermenter or keg at differing temperatures will cause it to gush
 
Ooo. Could be a school day.

I always thought Lactose was unfermentable sugar, whenever added.

From darkest memory this is because of the buggering about they do to make alcohol from milk whey, and even then it is not normal yeast (err by that I mean saccharomyces cerevisiae)
 
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Ooo. Could be a school day.

I always thought Lactose was unfermentable sugar, whenever added.

From darkest memory this is because of the buggering about they do to make alcohol from milk whey, and even then it is not normal yeast (err by that I mean saccharomyces cerevisiae)
It is unfermentable, hence the high FG.
 
Ooo. Could be a school day.

I always thought Lactose was unfermentable sugar, whenever added.

From darkest memory this is because of the buggering about they do to make alcohol from milk whey, and even then it is not normal yeast (err by that I mean saccharomyces cerevisiae)
It is unfermentable, hence the high FG. But now I am thinking, is the FG a true reading of the alcohol content? If all my base malt sugars fermented out could it be just the density of the lactose sugar propping up the FG?
Have I really reached my final gravity which was predicted? And it's just the lactose preventing an accurate reading?
 
It is unfermentable, hence the high FG.
Quite so. And it's unfermentable because brewer's yeast doesn't produce lactase or a similar enzyme. And my question, @MashBag , was whether an extended boil broke it down into fermentatable sugars.
Other yeasts, though, or GM yeasts may well be able to ferment it.
 
It is unfermentable, hence the high FG. But now I am thinking, is the FG a true reading of the alcohol content? If all my base malt sugars fermented out could it be just the density of the lactose sugar propping up the FG?
Have I really reached my final gravity which was predicted? And it's just the lactose preventing an accurate reading?
The lactose would have increased your OG reading, too, and since we estimate alcohol on the difference between OG and FG, your estimation should be as accurate as it usually is.
 
The lactose would have increased your OG reading, too, and since we estimate alcohol on the difference between OG and FG, your estimation should be as accurate as it usually is.
The only way I can prove this to myself is to brew it again and add the lactose after fermentation has finished unless I can find some formula online that can give how many points per hundred gram of lactose increases the density. I agree, the stout will be as predicted and the lactose is throwing in a false reading. This is more exciting than the sodium nitrite addition to bacon!
 
As I have quoted I add lactose after fermentation to sweeten to my preference but very carefully but it must change the FG so in my case it is true as I add it after taking the FG.
 
As I have quoted I add lactose after fermentation to sweeten to my preference but very carefully but it must change the FG so in my case it is true as I add it after taking the FG.
Have you taken before and after, The FG reading? It will save me from having to brew it again.
 
No unfortunately I did not Foxy I just sweetened to taste-should have from a scientific reasoning though but will next time
 
The only way I can prove this to myself is to brew it again and add the lactose after fermentation has finished unless I can find some formula online that can give how many points per hundred gram of lactose increases the density. I agree, the stout will be as predicted and the lactose is throwing in a false reading. This is more exciting than the sodium nitrite addition to bacon!
A better test would be to stand upright and see whether it takes the same number of pints as usual before you fall over. That's the way I'd do it, anyway. 😂
 

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