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Unformatted text preview: Brandon Pickett BY 123-Lab Topic #5: (1-10, 14) 1. Explain the limitations of Benedict’s test in determining whether or not sugar is present in a certain food product. Why do all monosaccharides, but only some disaccharides, react with Benedict’s reagent? In testing for the presence of sugar, Benedict’s test is effective except when both reactive groups (aldehyde and keytone) are involved in the bond between monosaccharides. In monosaccharides, only one reactive group is involved in the bond, leaving the other group free to react with Benedict’s reagent. The opposite is true in disaccharides. 2. What did you learn about the specificity of the biuret reagent? The biuret reagent reacts with peptide bonds and therefore reacts with proteins, but not with free amino acids. 3. In this lab, you used a biuret reagent to determine the presence of albumin (egg white) in solution. Why didn’t you use ninhydrin as the colorimetric reagent? We didn’t use ninhydrin as the colorimetric reagent because it reacts with the amino group of free amino acids, not with polypeptides—which egg albumin classifies as. amino acids, not with polypeptides—which egg albumin classifies as....
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- Spring '09
- Nutrition, free amino acids