Identifying Biological Macromolecules in Food Lab Essay Example

Identifying Biological Macromolecules in Food Lab
Stefanie Bogaert

Observations

Part 1: Test for Proteins
Biuret Test for Protein
Test Tube Contents Colour Change Conclusions
1 Distilled water Clear to Blue tint There are no proteins present because there was no significant colour change
2 Albumin White translucent to Purple/violet Therefore there are proteins present because of the significant purple colour exposed from the reaction of the Biuret solution
3 Pepsin Brown to Pink/brown There is a little to none trace of proteins in the pepsin due to the slight pink colour created from the reaction with the Biuret solution
4 Starch Clear to Blue tint There is no proteins in the contents because there was no colour change revealing the presents of proteins

Part 2: Test for Starch
Iodine Test for Starch
Test Tube Contents Colour Change Conclusions
1 Starch suspension White (starch) and brown (iodine) > dark blue-black Therefore starch is present due to the change of colour in the solution
2 Distilled water Transparent (water) and brown (iodine) > translucent orange (diluted iodine) Therefore starch is not present due to the lack of reaction in the solution

Part 3: Tests for Sugars
Typical Reactions for Benedict’s Solution
Chemical Chemical Category Benedict’s Solution
(after heating)
Distilled water Inorganic Blue (no change)
Glucose Monosaccharide
(carbohydrate) Varies with concentration: very low: green low: yellow moderate: yellow-orange high: orange very high: orange-red
Maltose Disaccharide
(carbohydrate) Varies with concentration
(see results for glucose)
Starch Polysaccharide (carbohydrate) Blue (no change)

Benedict’s Test for Sugars
Test Tube Contents Colour Change Conclusions
1 Distilled water Remains translucent blue There is no sugar in the new solution
2 Glucose solution Grass green, solution becomes opaque This solution contains a high concentration of sugars, to the degree of no longer being translucent, but