Title: Comparison of the chemical composition of various foods IntroductionCarbohydrate is a macromolecule made up of carbon, hydrogen and oxygen atoms. Carbohydrates or saccharides exist in 4 groups, monosaccharides, disaccharides, oligosaccharides and polysaccharides. Starch is one of the polysaccharides and consists of a large number of units of glucose molecules joined together by glycosidic bonds. Starch is made up of two types of molecules, linear and helical amylose and branched amylopectin. Potatoes have a large amount of starch as it is a staple food. Potato starch can be tested with the iodine test. When starch is present, iodine will take on a purplish-black color. Benedict's solution is used to test for the presence of reducing sugar. All monosaccharides are reducing sugars because they all have an active carboxyl group. The example of reducing sugars are glucose, fructose, lactose and maltose. Some disaccharides exposed to a carboxyl group also reduce sugar, but are less reactive than monosaccharides. By mixing the sugar solution with Benedict's solution and heating them under a water bath at 80℃, a redox reaction will occur. The copper(II) sulfate present in Benedict's solution, which exists as a light blue color, reacts with the electron from the aldehyde or ketose group of the reducing sugars to form copper oxide, which is a brick-red precipitate. The purpose of the Benedict test is to detect the presence of reducing sugars in a substance. Benedict's solution, which is the reagent for the test, will detect the presence of aldehydes and alpha-hydroxy-ketones. If a positive result is shown when Benedict's test was conducted, the substance will change color from c...... middle of the paper ......y Press9. http://zoologistbd.blogspot.com/2012/04/benedicts-test-for-reducing-sugars.html10. Omar Nahhas, Yahoo Contributor Network (July 22, 2009). Retrieved May 15, 2014, from http://voices.yahoo.com/the-chemical-constituents-living-matter-3856864.html11. Retrieved May 15, 2014, from http://en.wikipedia.org/wiki/Protein12. Retrieved May 15, 2014, from http://ansci.illinois.edu/static/ansc438/Milkcompsynth/milkcomp_protein.html13. Jones, M., & Taylor, D. (2007). AS and A Level Biology: Second Edition. Cambridge: Cambridge University Press.14. Starch, retrieved May 18, 2014. http://en.wikipedia.org/wiki/Starch15. Iodine test, retrieved May 18, 2014. http://en.wikipedia.org/wiki/Iodine_test16. Retrieved May 18, 2014. http://www.elmhurst.edu/~chm/vchembook/547starch.html17. Retrieved May 18, 2014. http://en.wikipedia.org/wiki/Carbohydrates