Re: how do i test quantitatively for sucrose, glucose and fructose ?

Aloha, Francis,

     Your questions took me back to my undergraduate days when I was a 
Chemistry major.  HOWEVER, that was in the early 1960s...and technology 
has changed greatly...even from the time when I completed my MS/PhD in 
Nutrition in the 1980s.  SO, I decided to seek some help from one of my 
food science colleagues in our Human Nutrition, Food and Animal Sciences 
department, here at the University of Hawaii, Manoa.  I spoke with Dr. 
Wayne Iwaoka this morning.  He confirmed that what you want to 
do 'chemically' just won't work...that is measure all the sugars somehow 
(colorimetrically, etc.).

      Dr. Iwaoka said that the best bet for measuring the sugars in fruit 
juice would be by HPLC (High Performance Liquid Chromatography), which is 
a commonly used technique in most chem/biochem labs, now.  It probably 
would have to be done on a dilute (and cleaned up) solution of the fruit 
juice.

     I did a quick search with Google using 'HPLC sugars'...and a number 
of hits came up, several of which looked like links to site with methods.  
Check those out, since they are either direct references or contain 
references to the literature.

Good luck on finishing your undergraduate program.

Dian Dooley