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build your own calorimeter?

Postby freakyfelice » Sun Nov 25, 2007 11:13 pm

i want to compare energy stored in different sources of carbohydrate, and i notice a serious dilemma~ for food like rice, noodle, and pasta~ do i have to cook them before measuring or just leave them raw? we are mostly prefer to eat cooked food than unsteamed rice and crunchy raw spaghetty, but could this experiment considered as valid if the energy of cooked rice and pasta are compared to the energy of raw uncooked cassava, yam, or whole wheat bread?
thank you =)

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Postby barretttomlinson » Mon Nov 26, 2007 1:57 am

I assume you are doing the "Burning Calories: How much energy is stored in different types of food?" experiment in the Science Fair Ideas guide on this site.

The writeup notes that much better results will br gotten with uncooked food. The problem is that to get good results the food sample must be completely burned, so there is nothing that will burn left. It is difficult to get food with a high water content(like cooked rice) to burn completely.
Professional scientists use a device called a bomb calorimeter to do this. In this device the sample is burned in high pressure oxygen. The problem is that this is very dangerous - the apparatus can explode!

So I think your concern is valid - testing raw food will give only approximately the value you would get if testing cooked food carefully. But as a practical matter, doing the experiment in the manner you are constrained to do, testing raw food will give much better results than trying to work with cooked food.

Congratulations on carefully thinking about your experiment!

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Postby freakyfelice » Mon Nov 26, 2007 3:01 am

thanks! veryy helpful...

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