Re: Will potassium bitartrate form an ester with a sugar?

It is not likely that an ester will form.  The way to test it, of course, 
would be using a separation technique such as thin-layer chromatography, 
or if you have access to the instrument, HPLC.  A change in viscosity 
might indicate that a reaction has taken place, although (1) it might not 
be the reaction that you expect, and (2) the viscosity will not 
necessarily increase as the size of the dissolved molecules increases.  
Viscosity is a very strange property that can be affected in surprising 
ways.  A very nice summary can be found at  http://hypertextbook.com/physics/matter/viscosity/