[yso191]

OK, I need to make some connections in what I have been learning so I can apply it to my beer.  I love a beer that has some perceived residual sweetness - it really turns on my taste buds and seems to allow me to pick up the various other flavors in a given beer.  I emphasised perceived because sugars includes starches which we cannot perceive as sweet.  I am interested in getting sugars that are tasteable, and (I think) not fermentable.  And that is what leads me to ask a couple of questions:

As I understand it, Maltotriose is semi-fermentable.  In other words brewers yeast will ferment some, but not all. 

1. Is this what accounts for perceived residual Sweetness (PRS)?
2. I imagine this could be yeast-strain dependent.  Am I correct in this?
3. I understand that Crystal Malts contribute to RS.  Is it because they have more Maltotriose?
4. Are the Crystal Malts equally sweet?  If not, where can I go to learn how they vary?
5. I also understand the Mash temp contributes to RS, but is it tasteable?  In other words, does targeting Alpha Amylase in one's mash actually contribute to perceived sweetness or just more unfermentable starches?

Or maybe I'm not even asking the right question yet.  If so, how does one get PRS in a beer?

[morticaixavier]

In my experience perceived sweetness can come from a few different sources.

Crystal malt, high mash temps - these lead to longer change and thus less fermentable sugars. These sugars tend to taste less sweet than shorter more fermentable sugars and lend body and mouthfeel as well as sweetness. How much of these sugars are fermented and how much is left is largely an effect of yeast strain. Which brings me to the second item on the list

Yeast Strain has a huge affect on perceived sweetness both because of how the yeast play with the hops and how that affects perceived bitterness (PRS is affected by PB and vice versa) and because of how yeast strain effects body and mouthfeel.

Carbonation. Higher carbonation tends to make flavours and aromas pop a little more. I find that with yeast strains that accentuate sweetness and vinous flavor characteristics (Belgian and saison yeast particularly) more carbonation can actually accentuate fullness in the body by building a thick creamy head and making the beer seem to fill your mouth more. Whereas with a full bodies british beer too much carbonation can actually make them seem brighter and more refreshing which can be nice or not so nice depending on what you are after.

Pilsner malt. Pilsner malt, in my experience adds a lovely grape like sweetness even when it ferments out pretty dry. It can be overwhelming but if not used to excess it can add a nice bit of perceived sweetness that will not ferment out.

That's about all I got. Hope it helps.

[kmshultz]

In my experience, mashing high to favor alpha amylase (and hence less-fermentable sugar) does *not* necessarily increase the perception of sweetness -- just the body/head.

Crystal malts are certainly a way to get some perceived sweetness guaranteed, but not all crystal malts are created equal. They vary not just in color, but also flavor and level of perceived sweetness. The lighter color Crystal malts (40L or less) tend to taste more lightly caramel-sweet (think candy), whereas the darker Crystals can have raisin and dark fruit flavors which do not taste as sweet.

I would echo what morticaixavier said about yeast strain choice as well. Lower attenuation yeasts (particularly British type, like WLP002) can leave a perception of sweetness, and perhaps the apple/pear fruity esters contribute to that impression as well.

Cheers,
Kent

[yso191]

Great info guys, that is what I was looking for!

[Jimmy K]

There is another angle your not thinking about - hops. Bitterness from hops balances sweetness from malt, in fact without hops every beer would be very sweet.  If you want more residual sweetness in a beer, you might start by reducing the IBU's a little, specifically the bittering hop addition.