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Use of lactose sugars and exogenous enzymes

My goal is to build a beer that is over 15% ABV with a fairly strong pineapple flavor but also has a great deal of residual sweetness. Part of my issue is that I don’t want to stress the yeast or back sweeten, and I want the mash to finish out clean.

Obviously I’ll be mashing at a low temp of around 145 or so to get plenty of fermentable sugars.
I’m trying to decide when to add the pineapple, I’m thinking at about 10 min.
My concern is that during fermentation the yeast will eat all the fructose from the pineapple which is not a bad thing but I do want to keep the sweetness so I was thinking of using a lactose sugar to pump the body and sweetness in a controlled fashion.
Also using an exogenous enzyme, alpha amylase to encourage a complete fermentation has me wondering if it would convert the lactose sugar into fermentable sugars?

Discuss!

I can’t answer all of your questions, and some might disagree with my thoughts here, but I would add any fruit to a secondary fermenter. The high activity of the primary fermentation will blow off most of the fruit’s flavor (CO2 will scrub it out). The boil isn’t going to help either. I would crush the pineapple and pasteurize for 20 minutes at 165 degrees. I have not found much loss in fruit flavor doing this, but some brewers just throw in the unpasteurized fruit in secondary with the idea that there’s enough alchohol in the beer at that point to prevent any bacterial growth.

I would add the lactose to the end of the boil (maybe 15 minutes before flame out). I have no idea if the amylase would break down lactose, but it is a dissaccharide of glucose and galactose if I remember correctly, so I guess it could be cleaved. By adding it to the end of the boil, you have denatured all of the enzymes in the wort, so the lactose will definitely not get broken down.

I have no experience with the use of exogenous enzymes, and I would agree it will probably increase your fermentability of your wort, but big beers tend to have a lot of body, and mashing at 145 sounds might make a highly alcoholic but very thin beer. The lactose will help, but I’m wondering if you’ll need a couple pounds of caramel / crystal malt or some dextin. A strong beer should have plenty of backbone to support all that alcohol. This is where your residual sweetness will come in. I don’t think you’ll get much of that from the pineapple. Are you planning on kegging and force carbonating this one or bottle condition?

I agree wit @brewdvm about the addition of pineapple. Boiling it will cause permanent haze and the aromatics will be scrubbed by CO2. The sugars provided will also create a thin beer, as it is almost 100% fermentable.

Amylase enzyme shouldn’t cleave the lactose. But this also contributes to a thin body as it is going to convert more starches to fermentable sugar. So, couple that with a low mash temp, using amylase enzyme, and fermentable juice you’ll end up with a pretty thin beer. This could call for a lot of lactose.

I would chose a yeast with higher alcohol tolerance and use a grain bill/mash temp that leaves more resudual sugar as this will hope promote that sweetness you’re looking for.

Your kind of contradicting yourself. You are doing everything to thin the beer and adding lactose to build it back up. Might also considering getting some pineapple extract to tailor the pineapple affect your looking for. Fruit will completely ferment leaving only alcohol.

Consider adding lactose after fermentation. Taste the fermented beer and add to taste.

Add lactose BEFORE carbonating - each tiny crystal becomes a nucleation site for a bubble of CO2. I added lactose to a keg of carbonated beer and created a volcano.

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