Using Lactose for Sweetening

[Benfleet Brewery]

I’ve only just seen this thread and ironically I made my first ever Milk Stout at the weekend. I followed this recipe which someone else had shared in a previous thread but scaled down the grist to hopefully end up with something closer to 5% abv than 7%!
https://www.homebrewersassociation.org/homebrew-recipe/left-hand-milk-stout-clone/
Since it is only just made I can’t comment on FG. I’ll have to report back.
I added the lactose to the boil 15 minutes before the end using the same method as I use when adding any other sugar and it dissolved really easily. I put it into a large bowl and opened the tap into it during the boil to mix the hot wort with the sugar, added this to the boil then do it one more time to rinse out anything that’s left.

 

[foxy]

I’ve only just seen this thread and ironically I made my first ever Milk Stout at the weekend. I followed this recipe which someone else had shared in a previous thread but scaled down the grist to hopefully end up with something closer to 5% abv than 7%!
https://www.homebrewersassociation.org/homebrew-recipe/left-hand-milk-stout-clone/
Since it is only just made I can’t comment on FG. I’ll have to report back.
I added the lactose to the boil 15 minutes before the end using the same method as I use when adding any other sugar and it dissolved really easily. I put it into a large bowl and opened the tap into it during the boil to mix the hot wort with the sugar, added this to the boil then do it one more time to rinse out anything that’s left.

I noticed that it had no trouble at all dissolving, dissolves better than table sugar due to the finer granules. From what I have read in the short time so far don't be upset if your final gravity is skewed, you will still have the gravity you were aiming for or close to it. The lactose does throw it of and there is a formula to work out how much.

 

[Benfleet Brewery]

I noticed that it had no trouble at all dissolving, dissolves better than table sugar due to the finer granules. From what I have read in the short time so far don't be upset if your final gravity is skewed, you will still have the gravity you were aiming for or close to it. The lactose does throw it of and there is a formula to work out how much.

I use Brewers Friend. Having made the adjustments to try to get an abv of 5% it predicted a OG of 1.054 and that was stop on.

 

[foxy]

I use Brewers Friend. Having made the adjustments to try to get an abv of 5% it predicted a OG of 1.054 and that was stop on.

The OG is the easy part it is the FG that throws a spanner in the works. There is a calculation I saw on Reddit that gives lbs/gallon calculation but I don't understand imperial and at this time of night with a few drinks under my belt can't be bothered to do the conversion.

 

[Hazelwood Brewery]

Lactose and regular table sugar have the same “points per pound per gallon” (US measures) which is 46. This means if you add the same weight of lactose or sucrose you will raise the gravity of your wort by the same amount.

The difference is the fermentability using regular yeast (saccharomyces cerevisiae) - the amount of sucrose converted to alcohol is pretty close to 100% , the amount of lactose converted to alcohol is 0%.

Your wort, produced from mashing grain, will contain a range of sugars. Some of these will be easily digestible by regular yeast, others will be less digestible. Depending on the genetic variation of the yeast you will convert typically between 70% and 90% of these sugars.

If you brew a beer with a regular mash and add sucrose and lactose you can expect to convert around 80% of the wort sugars (in accordance with the yeasts attenuation) plus 100% of the sucrose plus 0% of the lactose.

A wort gravity of 1050, raised to 1060 by adding sucrose and raised again to 1070 by adding lactose might end up (assuming a yeast attenuation of 80%) at 1020 because you’ll have 20% of the sugar from the mash, 0% of the sucrose, and 100% of the lactose unfermented. In reality this might not be exact because environmental factors in the wort and the attenuation of the yeast are not exact or fixed but you won’t be too far adrift.