[Ballistic]

Bit of a dilema, sugar testing, can you help me out?

Hi, I want to test food colour powder for added sugar, where the  maker says it's pure.

The trouble is I have Benedicts solution, however, the powder will turn the solution red because it's powdered colour.

Is there any other way to test for sugar (I don't really want to taste it)?

Thinking logically, it will need to be a reaction to produce some effect other than a colour change?

It's E129 which is an Allura Red Azo Dye. Your thoughts however random or profound are appreciated exceedingly.

[Borek]

Do you have a reason to not believe the specification?

In general - it won't be that easy. Benedict solution doesn't react just with sugars, it reacts with aldehydes and alpha-hydroxy-ketones. While these are commonly sugars, it doesn't mean positive result means sugar is present.

How does the powder look? Is it homogeneous? Check what happens when you dissolve some and let it dry, even if it is a fine mixture now it should produce separate crystals. Then you will know something is wrong.

[Ballistic]

Do you really think that wetting and drying will work? It's just that I am used to seeing dyes go wet and dry with other additives in and by it's nature the dye covers everything and gets everywhere. i.e. you can actually grow crystals that are coloured with dye in the solution.

[Ballistic]

What I've decided to do tomorrow is put it in solution in some warm water and add active yeast and see if it starts to give off carbon dioxide as it ferments.  This will be a little "hint" I'm onto something.

Further ideas - haven't I seen a guy demonstrating how to release the energy in sugar using some other chemicals or oxidisers etc? Any idea like this?

[Borek]

Unless there is really a lot of sugar, you won't see anything.

There are no simple and easy tests that I am aware of that will help you. I repeat my question: do you have reasons to not trust the specification?

[Ballistic]

Yes, it doesn't look or feel like the real McCoy, which I am used to dealing with. - Just to add - that I think it might be 75% sugar judging by it's poor strength to answer your other point.

[billnotgatez]

There is a way of testing for ethanol when brewing.
Take the specific gravity before the yeast start working and after
If it is minute amount of sugar that may not work, but leave no stone unturned.
I also want to know

[HarryA]

Back in the good old days we used refractometers to measure the sugar in maple sap.

[Ballistic]

Yes, good point, refractory index is another thing. The only thing is I think I would need a laser to shine through dyed water but I could be wrong.

[Ballistic]

OK, well I know this could have got interesting, but I don't need to proceed. By going through their own documents, I can see they are selling "Lake" colours and passing them off to the public as pure "E" numbers.
If you are interested from the FDA web site "Lakes are formed by chemically reacting straight colors with precipitants and substrata (for example, Blue 1 Lake). "...   "for food use are made with aluminum cation as the precipitant and aluminum hydroxide as the substratum."
By the morning, all the colour had dropped out of solution anyway, whereas E129 is fully water soluble.

[billnotgatez]

@Ballistic
So your

poor strength

that you reported here
is due to something other than sugar?