Tom, all I can give you are general comments right now. My notebooks are at work right now, as I was going to run some of the stats through our lab's statistician to make sure my methods and results are valid.
Do a Google search of Steevia (the brand of stevia I used) and you'll get my earlier comments on it. It is stable for short term use in an unfiltered, unstabilized wine, but utilizing it that way was a mistake for reasons having nothing to do with stevia -- it was just silly not to stabilize the wine first. It does break down and will ferment. If the wine is stable, it will still break down after about three months and does two things I have seen several times now. (1) It jeopardizes the clarity of the wine. A brilliant wine will degrade into a clear wine, no longer brilliant. A clear wine will ytake on a very slight haze. There are no particulants and no cloudiness, but a very slight haze that can be seen with a flashlight or laser pointer passed through the bottle. (2) It can (but not always) develop a slight off taste, almost metallic. I couldn't believe this, as this was not evident until at least three months had passed. If the off taste appears, it gets slightly worse after detection and then seems to level off. I have noticed it most in citric-dominant wines, a couple of times in malic wines, but not in tartaric wines (grape). (3) I have noticed a very slight fizz a couple of times, almost like a malolactic fermentation has finished in the bottle.
Having said all of that, I still say it is a good sweetener if you just want to sweeten a wine for near-term consumption. I am assuming you are using just the minimum amount necessary to balance a slightly acidic or too alcoholic wine. It doesn't bring out fruit flavors the way sugar will, but it does sweeten a wine. If you use too much, you may indice a slightly off taste; I have never done this, but others have reported it.
Splenda is another animal and almost a delight to use. I have never had a malto-dextrose tainting problem, but I am aware of the potential. Just keep everything very clean and you'll have the odds on your side. It brings out fruitiness as it sweetens dry wines, just as sugar does, but perhaps not as much. This is a difficult thing to judge because I've only run one side-by-side comparison of the same wine with both Splenda and sugar and I couldn't taste the difference but two others chose the sugared wine for fruitiness in a blind tasting. My complaint with it is that it doesn't seem to add any body to a thing wine the way sugar does. I actually tried to measure this, but doubt that I succeeded. That is what I'm having checked, but I've been too busy at work to actually present the data for analysis. Even so, I don't think it contributes to body or mouthfeel the way sugar does.
I have slightly sweetened (1%) two wines with pure malto-dextrin. I do not recommend it for every wine, but think it might be okay for some. I hesitate to say more about it at this time as only one of the two wines has gone past six-months and I haven't tasted it recently.
That's all I'm willing to say right now. Okay, one more thing. I don't think any of these will prove to be better than sugar, but for diabetics they may offer some potential.
Jack Keller, The Winemaking Home Page
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