Layne 'Musashi' Westover wrote:
>       If I understood correctly, when sucrose is inverted, there is
>the release of a water molecule.

        bad start; exactly wrong.  Hydrolysis  *destroys*  one water
molecule for each sucrose molecule that is split to give two
monosaccharides (one glucose + one fructose molecule).  The atoms of that
water molecule are incorporated into the newly-created molecules and that
water molecule is no more.
        I hasten to add that, as a contribution to the increase of osmotic
pressure (expounded by Blane), this chemical destruction of water by its
getting used up in hydrolysis is a very minor aspect.
        The main phenomenon, as I tried to point out and others have
underlined, is that the concentration of 'water-loving' molecules is
doubled by the splitting of sucrose to the two monoses.   This is at least
a reason, if not the only one, why honey is much more hygroscopic than dry
sucrose.
        But such comparisons are not made by casual inspection.  To open up
just a glimpse of what causes chemistry students much work, you should
distinguish 'chemical potential' (loosely analogous to voltage) or 'driving
force' (I'm getting real slangy here) from chemical kinetics (the RATE at
which a chemical reaction actually occurs.  The two have no particular
connection in fact.  A reaction with a very strong driving force can show
no discernible rate of reaction.  The ultimate potential for a gram of
sucrose to absorb water cannot be estimated from the sluggishness with
which it initially does so, compared with the rate of uptake of water by a
gram of 'invert sugar'.

        But let me put all this simple chemistry in some perspective please.
        The properties of honey are largely unexplained by these
considerations of its main chemical constituents.  (This reminds me of the
fact that many important properties of the atmosphere are dominated by its
trace constituents.)  Professor Molan at the U of Waikato, the world's
leading biochemist on honey, has been trying for many years to identify the
trace components which cause the antibiotic properties.  He is a very good
biochemist but has made little progress on this analysis.  Synergism
between the many components of honey may well dominate the overall effects.
The simple sugars are only the bare start of this glorious tangle.  The
hygroscopic nature of honey is a main cause of its matchless merit as a
wound dressing; it takes water out of the wounded tissues at just right
rate to inhibit microbial growth, facilitate debridement, etc; this process
is only crudely explained by my first 3 paras above.

        Anyhow I would deprecate the use of the term 'dry' for any version
of honey.

R



-
Robt Mann
Mulgoon Professor emeritus of Environmental Studies, U of Auckland
consultant stirrer & motorcyclist
P O Box 28878, Remuera, Auckland 1005, New Zealand  (9) 524 2949