lactose

[W0nderW0man]

When should I add the lactose? and how to I calculate the percentage (from the full mash volume, batch size or as part of the mash?) I have noticed that lactose comes as part of the mash in the recipe builder, which would suggest me to use 220gr for a 12l batch as 8%. However I have read that people tend to add it only the last 10mins of the boil.

 

[Hoppy]

As lactose is unfermentable, as long as its sterile, it really doesn't matter when you add it, ten minutes sounds fine. This will increase your final gravity though.
You are probably looking for about 4 degrees in gravity. With lactose having an extract of 300 litre degrees of gravity/kg, means a 12 litre brew will need 4 degrees sac x 12 litres, 48 litre degrees. 48/300=0.160 litres, a little lower than your 220g.
Lactose has some undesirable effects, don't go too high!

WBR
Hoppy

 

[HebridesRob]

The point of lactose is it's non-fermentable so sweetens your beer. This means it doesn't matter when you add it so I would add just before bottling. Take a glass of beer, dissolve half a spoon at a time and taste until you're satisfied, then scale up.

If you're adding a pre-determined amount it won't affect all your hydrometer readings if you add right at the end.

 

[Hoppy]

The point of lactose was not to sweeten, but to change mouth feel to prevent the astringency of the burnt malt tastes in stouts without changing mashing to increase unfermentables and therefore reduce extract efficiency (need to keep the accountants happy, malt in and ABV out) and also incurring the wrath on Her Majesty's Customs and excise as it doesn't add to the ABV when it was drunk at a later date!
WBR
Hoppy