YT2095 - 8-2-2007 at 10:43
this is in here for a more than evident reason (I have no idea what I`m on about)
I`ve read about Optical rotation of sugars (boiling in HCl etc...)
now when you have 2 polarized films/plates in the same polarity light passes through.
rotate one plate by 90 degrees and it goes Black, No light passes.
(think LCD principal for watches).
would it be possible to make polarized sugar crystals where the combined effect would APPEAR as Black Sugar?
unionised - 8-2-2007 at 11:01
No, or at least I very much doubt it.
Polarising filters work by selectively absorbing light polarised in one direction. Sugar has no chromophore to absorb (visible) light. It cannot,
therefore be made into a polariser.
Also, different wavelengths of light are rotated by different extents so you would get one colour selectively absorbed. Black would need absorbtion at
all wavelengths.
The optical rotation also depends on the pathlength. All the sugar crystals would need to be exactly the right size for the rotation to be exactly 90
degrees.
Pity really, because it would look really neat to have a colourless solution giving black crystal when the water evaporated.
WWGroove - 8-2-2007 at 15:28
I suppose you know about sugar and H2SO4 and I'm talking rubbish.
Sugar appear black,still sweet.
Not what you're after ,for sure
[Edited on 8-2-2007 by WWGroove]
WWGroove - 8-2-2007 at 15:53
I put a g. of sugar,few drops H2SO4 in a petri.Yellow
Microwave 2 sec., is black,but not sugar anymore.
There is a candy industry process to make black sugar.No colors added.
Not sure if after hydrolysis and recrist. get to black sugar.
Ozone - 8-2-2007 at 16:35
Actually, yes, color is "added" by making it in-situ. The sugar is heated at high solids loading, viz. _>_50% in the presence of an amino acid. The
subsequent series of reactions, aka. the "Maillard rxn" takes place to first:
1. make some caramel which is largely composed of hydroxymethylfurfura which then hydrolyzes into levulinic and formic acids lowering the pH.
2. The lower pH and high temperature _>_95°C lead to sucrose inversion and a greater amount of feed for the Maillard reaction, viz. glucose and
fructose.
The color can be controlled by reaction conditions to yield anywhere from light yellow to black. The color is actually *mostly* a condensation product
of reducing sugar and amino acid; the upper molecularweight is ~20,000, or so. The darker you get, the less sugar you have.
The colored polymer (and increaseed invert content) also tends to disrupt crystallization (presumably in the usual way) making crystallization
processes tricky and low yielding. What you might see would be color occluded into the crystals *or* added back in (mother liquor, molasses) and
dried.
Never seen or heard of the stuff myself, we are usually shooting for "refined white" at least EU #2 with an ICUMSA color _< 40 (preferably ~20).
Sweet!
O3
WWGroove - 9-2-2007 at 10:10
Try search "epifania carbone"
WWGroove - 11-2-2007 at 17:01
Not pure sugar.
0.7Kg sugar 300ml water some acetic or citric acid. caramelize
add white egg,0.3 icing sugar,black food color if desired.Cool.break off.
If we belive Shulgin,then is chemistry.