Science Buddies: "Ask an Expert"

what are good tests on cooking oils for an expo?

URGENT- can you please explain thoroughly how iodine tests for SATURATED FATS. because websites have stated that it actually tests UNSATURATED FATS. i need to know how it relates to saturated very urgent!! thank you Expert

"test if a lipid is saturated or unsaturated by adding iodine to various substances. If the iodine changes from brown to clear the lipid is unsaturated. If the iodine does not change colors the lipid is saturated."

excerpt from

http://www.education.com/science-fair/a ... d-testing/

Hope this helps.

thank you, but other experiments say that another way to determine how much saturated fat is to time how long is takes for the iodine to take the colour of the various different cooking oils. And the longer time taken, the more saturated fat in the cooking oil. why is this? ive been on every possible website but cannot find an accurate answer.

I'll ask around and see if someone more knowledgeable about organic chemistry is available.

gabi w,

The color change of iodine happens when the iodine reacts with the oil. The total amount of iodine that will change color is proportional to the amount of unsaturated fat. The rate at which the color change happens also depends on the amount of unsaturated fat, but it also depends on the temperature, whether the fat is stirred, and other factors.

WW

thank you so much expert, is there any way that by doing this iodine test measuring unsaturated fats, it inversely tells the saturated levels. Because I've done the experiments with 4 different cooking oils, but in my results i stated that i was measuring the saturated fat amount and i timed how long it takes for the 2 drops of iodine to take the colour of each cooking oil. i said that the longer it takes, the more saturated fat in the oil. any way i could fix this problem? thank you for all you help! it is much apreciated !!

gabi w,

Well, the amount of iodine that has its color changed does, in fact, depend on the amount of unsaturated fat. Of course, any sample of fat is made up of unsaturated plus saturated. Thus, if you measure the amount of unsaturated fat, what's left over is saturated.

Does this help?

WW

thank you.. is it correct that..
if you add the same amount of iodine to several cooking oils, does the cooking oil that takes the longest time for the iodine to clear contain the most saturated fat?

URGENT- project due tomorrow. please help as soon as possible. much appreciated science buddies expert!

no one have an answer to help me?? its seriously urgent