Re: testing amounts of sugar in sweets

Hi Karen.  Your suggestion for a method of testing the amount of sugar in 
sweets is a good one.  The only problems that you'll face is that while you 
evaporate away the water, you'll also evaporate away any other volatile 
materials in the candy (for example, flavors and perfumes are very volatile 
(meaning that they have high vapor pressures...you can experiment with this 
by leaving the cap off a bottle of perfume (better make sure it's cheap 
perfume!).  You leave behind everything that's not volatile, which is 
probably sugar, binders, coloring, etc.  As long as the amount of sugar is 
much larger than the amount of non-volatiles, then you're ok to test the 
candy this way (for example, for hard candies, it's probably ok, but 
probably not ok for a chocolate bar).  

To do your experiment, you just weigh a container empty, and then again 
with the candy in it (use a balance which can weigh to the nearest 
milligram or better...probably can be found in a high school chem lab).  
The difference is the weight of the candy.  Add water, evaporate, and 
re-weigh.  The difference between that weight and the first weight (empty) 
is the weight of the sugar.  The ratio of the weight of the sugar to the 
weight of the candy (multiplied by 100) gives you the fractional weight of 
the candy as sugar (I think most people would be amazed to find what a high 
percentage it is!).

Let me conclude by saying that if you want to test your candy the same way 
the companies do, you can call up a candy company and ask to talk to 
someone in their quality control lab.  These labs are responsible for 
testing randomly chosen samples of their candy to make certain that they 
adhere to the standards the company or government sets.  This lab will have 
a set of procedures for determining the sugar content of the candy, and 
will probably be willing to fax or send them to you (these are usually 
procedures which are created by the government so that all people test 
things the same way).

Hope this helps.
If you have any other questions, please feel free to email me at 
weibel@chemistry.chem.utah.edu

Best Regards,
Mike Weibel