Clinitest As A Quantitative Measure of RS

You might have noticed that I can be something of a pit bull. My grandmother is said to have remarked when I was a baby that "Daniel is very persistent". Pit bulls were uncommon then, and she wouldn't have wanted to hurt my mother's feelings anyway, but you get the idea.

This time I've latched on to the question of measuring RS in a finished wine. In another thread here http://www.wineloverspage.com/forum/village/viewtopic.php?t=4717&sid=dbd413ece73450de9512e47a0e4e7de0, good reasons are given for the inappropriateness of a hydrometer for that purpose. What then can the home winemaker do? Many of us have used Clinitest on word of mouth that it is sufficiently accurate for our purposes. But when I've tried looking into the matter it has been hard to find informed discussion. Recently, I came across a discussion at another site that includes the usual flailing about but, in addition, comments by some that seem quite interesting. See particularly the last post (on page 2) by a commercial winemaker.


None of this, as far I can tell, moves the discussion very much at the level of chemistry. I couldn't judge that anyway, but others here probably could. Anyway, here is the link:
http://www.winepress.us/forums/lofiversion/index.php?t9645.html

Interesting discussion on the meters vs. the Clinitest. From the sounds of things, I'd agree that Clinitest should give a good ballpark figure. The meters don't sound like a good alternative.


Mike

Dan, I'm not a chemist either but am an occasional home winemaker who has done some reading on this subject. "Your" thread agrees with my understanding that most meters and diabetes stick-type tests are not useful in winemaking because they employ a reaction that specifically detects only glucose (the sugar involved in diabetes) and can't find fructose, a prevalent sugar in grapes. Clinitest, on the other hand, employs a reaction that detects all "reducing sugars". Glucose is one of those; fructose technically is not but it's my understanding that through some other chemistry that I haven't figured out, fructose breaks down into something that Clinitest does detect. If you want to read more on the subject of the various sugars, try going to Wikipedia and starting with "reducing sugar". Or Google on that or "Benedict's reagent", of which I gather Clinitest is an example.

Bottom line, Clinitest is the best and pretty much only thing going for home winemakers trying to detect residual sugar, as far as I know. For myself, although, as you say, a hyrdometer is a very crude tool for measuring residual sugar, if I get down to specific gravity 0.992 or so, I figure that's dry.