The Structure of Sucrose

Common table sugar is granulated sucrose, extracted from beets or cane.

" Sucrose, or cane sugar, is a two sugar molecule (disaccharide). It is formed by a chemical bond between the two simple sugars (monosaccharides) glucose and fructose. Even though glucose and fructose have the same chemical composition, C6H12O6, their structure is actually quite different. "

http://www.ccrc.uga.edu/~rcarlson/CarbInt.PDF
http://www.chem.umd.edu/courses/chem233/chapterspdf/main9-pages-pdf.pdf
more specific rotation values:
http://www.colby.edu/chemistry/CH367/bc367lab6.pdf

The Inversion of Sucrose

The disaccharide fructose can be broken down into glucose and fructose, in at least 2 distinct ways: chemically (with an acid) or with an enzyme (for example invertase). The chemical way produces l-fructose (aka levulose), while invertase produces d-frucose. In both cases the glucose remains the original d-glucose (aka dextrose).

" Sucrose hydrolyzes in acidic solution to give dextrose and levulose (d- and l-glucose). The rate of the reaction will be influenced by the concentration of hydrogen ions in the solution. "
(Note: The reference to l-glucose is incorrect, the author means d-glucose and l-fructose).

C12H22O11 + H2O = C6H12O6 (dextrose) + C6H12O6 (levulose)

" We may follow the progress of the reaction by monitoring the angle through which light is rotated by the solution. Sucrose and dextrose are both dextrorotatory, but the levulose is more levorotatory than the dextrose is rotatory. Thus, as the inversion continues, the solution becomes more levorotatory. At equilibrium, a final angle of rotation is observed, which will be proportional to the initial concentration of the solution. "
http://academic.uofs.edu/faculty/cab302/courses/360_8.html
http://physchemlab.tau.ac.il/experiments/Sucrose/Sucrose.htm

Corn Syrup

Corn syrup is d-glucose (dextrose). Unless it is high fructose corn syrup (HFCS) in which case it is mostly fructose (d-fructose). In the US, commercial Karo syrup light is an easily available HFCS.

" The fructose in HFCS is produced by the plant enzyme invertase (in humans the enzyme sucrase plays that role). The enzyme also flips the fructose from its original l-form to its d- form, hence its name invertase. "
http://www.enzymes.co.uk/answer45_invertase.htm (cached).

http://www.sbu.ac.uk/biology/enztech/sucrose.html

" Laser light is naturally polarized. Scattering from a laser beam passing through an optically neutral sample will be prominent at 90 degrees to the polarization and vanish in the direction of the polarization. Scattering from a laser beam passing through an optically active sample will show a periodic dimming and brightening of the scattered light as the polarization direction rotates through the sample. In corn syrup a 180 degree turn is achieved over about 15 cm. "
http://www.ph.ed.ac.uk/~nef/schools/opt-act/opt-act.html, [local copy]