How do you test the sugar content of fruit?

Question

any ideas?

thanks

Answer 1

honestly why would you want to?

=|

some peoples random thoughts never cease to amaze me.

x

Answer 2

you can measure the reducing sugar content of fruit ( glucose and fructose ) using the Fehling's reaction. The Fehling's reagent ( recipe on the NET) reacts with reducing sugards to produce red cuprous oxide. Make a standard curve of known glucose concentrations, react them with the Fehling's reagent, remove the precipitate of Cu2O and measure the remaining blue color at ~ 600nm. You will have a "standard curve" with a NEGATIVE slope. Treat your unknown solution with the Fehling's and measure its residual blue color.....find the "glucose equivalents " on the standard curve..adjust for any dilution and you have a semi-quantitative method for the total reducing sugars..

Answer 3

Traditionally in the wine making business you measure the density of the grape juice using a hydrometer.  Fruit juice is mostly water.  Sugar solutions are more dense than water, by a little.  A hydrometer is a glass bulb float with a tall graduated stem.  The more dense the juice (more sugar) the higher the stem extends above the liquid surface.  The sugar content is traditionally measured in degrees Brix.

There are other analytical methods to sort out the distributions of the types of sugars: glucose, sucrose, fructose, etc.