Glucose levels (w invertase) for coke and orange juice

Ask questions about projects relating to: aerodynamics or hydrodynamics, astronomy, chemistry, electricity, electronics, physics, or engineering.

Moderators: MelissaB, kgudger, Ray Trent, Moderators

Glucose levels (w invertase) for coke and orange juice

Postby pn66 » Tue Mar 19, 2013 12:06 pm

My son is doing - Sucrose, Fructose and Glucose - oh my uncovering hidden sugars - project for science fair, and is in the process of analyzing the data. ( ... p035.shtml)
For coke and orange juice (with 1:10 dilution) the glucose levels were 1.0 before adding invertase and 1/2 at linear point (15 mins) after adding invertase. He was expecting the numbers to go up and not sure why the numbers went down? Is this expected? For other foods the numbers were low before and high later.

Posts: 1
Joined: Mon Mar 18, 2013 3:15 pm
Occupation: Engineer
Project Question: For coke and orange juice (with a 1:10 dilution), before putting the invertase the glucose level was 1%, but after the invertase it was 1/2%. We were expecting the numbers to go higher. Can you please explain why the glucose level is lower? Thank you.
Project Due Date: March 28, 2013
Project Status: I am finished with my experiment and analyzing the data

Re: Glucose levels (w invertase) for coke and orange juice

Postby wendellwiggins » Tue Mar 19, 2013 3:53 pm

Hello pn66,

You are right to expect the glucose level to rise in orange juice when invertase is added. It should roughly double since orange juice contains enough sucrose to provide about as much added glucose after invertase is added as was present in the juice before invertase.

I don't know why the reading dropped in your experiment. One possible factor is that the test strips don't read beyond 2%. Maybe something unexpected occurred when the strip was immersed in the more concentrated sugar. You might try diluting the juice 1:20 and repeating the experiment with the more dilute liquids.

Good luck, WW
Posts: 338
Joined: Sun Jul 10, 2011 5:48 pm
Occupation: retired physicist
Project Question: n/a
Project Due Date: n/a
Project Status: Not applicable

Return to Grades 6-8: Physical Science

Who is online

Users browsing this forum: No registered users and 2 guests