Food Nutrient Analysis Lab PDF

Preview

Summary

Download Food Nutrient Analysis Lab PDF

Description

Food Nutrient Analysis Lab Food Nutrient Analysis Lab Purpose: The purpose of this experiment was to complete biochemical tests for the presence of starch, vitamin C, sugar, protein, and lipids. The results will determine the specific organic compounds found in the unknown solutions. Materials: The materials used in this experiment were test tubes, measuring cup, color pencil, water bath, gloves, unknown five, unknown six, water, iodine solution, starch solution, dichloroindophenol, ascorbic acid, Benedict’s solution, sugar solution, protein solution, biuret reagent, vegetable oil, Sudan IV. Method: Prepare four test tubes, labeling each 1, 2, 3, and 4. A. Iodine Test for Starch 1. 5 ml of water and 4 drops of iodine solution was placed into each of the four test tubes. 2. 10 drops of water was added to tube 1. 3. 10 drops of starch solution was added to tube 2. 4. 10 drops of unknown five was added to tube 3. 5. 10 drops of unknown six was added to tube 4. 6. Record any color changes. B. Indophenol Test for Vitamin C 1. 20 drops of indophenol solution, dichloroindophenol, was added to each of the four test tubes. 2. 3 drops of water was added to tube 1. 3. 3 drops of vitamin C, ascorbic acid, was added to tube 2.

4. 3 drops of unknown five was added to tube 3. 5. 3 drops of unknown six was added to tube 4. 6. Shake the vials and record color changes. 7. If no color change occurs, add more of the respective solution, 1 drop at a time until color change. C. Benedict’s Test for Reducing Sugars 1. 5 ml of water and 20 drops of Benedict’s solution was placed into each of the four test tubes. 2. 10 drops of water was added to tube 1. 3. 10 drops of sugar solution was added to tube 2. 4. 10 drops of unknown five was added to tube 3. 5. 10 drops of unknown six was added to tube 4. 6. Each of the four test tubes was placed in the hot water bath for five minutes. 7. Remove after five minutes and record color changes. D. Biuret Test for Protein 1. 5 ml of water was added to each of the four test tubes. 2. 10 drops of water was added to tube 1. 3. 10 drops of protein solution was added to tube 2. 4. 10 drops of unknown five was added to tube 3. 5. 10 drops of unknown six was added to tube 4. 6. 30 drops of biuret reagent was added to each of the four test tubes. 7. Record color changes. E. Sudan IV Test for Lipid

1. 5 ml of water was added to each of the four test tubes. 2. 10 drops of water was added to tube 1. 3. 10 drops of vegetable oil was added to tube 2. 4. 10 drops of unknown five was added to tube 3. 5. 10 drops of unknown six was added to tube 4. 6. 3 drops of Sudan IV was added to each of the four test tubes. 7. Shake each tube and let rest for 3 minutes. 8. Record results. Sugar

Starch

Negative Control (indicator reagent + H2O)

Blue (no change)

Orange-ish (no change)

Light pink (no Blue (no change) change)

Dark blue (no change)

negative

negative

Negative

negative

negative

Positive Control (indicator reagent + H2O + pure known nutrient)

Orange

Black

Light pink, layer on top

Purple

Light yellow

positive

positive

positive

positive

positive

Unknown Five

Blue, layer on Orange-ish, layer on top top (no (no change) change)

Light pink, layer on top

Dark blue (no Blue (no change) thick change) layer on top layer on top

Unknown Six

Lipid Name of

Protein

Vitamin C

negative

negative

positive

negative

negative

Dark orange

Orange-ish (no change)

Light pink (no Blue (no change) change)

Magneta

positive

negative

negative

negative

positive

Results: Based on the results above, unknown five is olive oil and unknown six is ginger ale.

Material Tested

Unknown five did not mix with the solutions, rather formed a layer at the top. Oil does not mix with water because water molecules are polar and oil molecules are non-polar. Oil is less dense then water, forcing it to float to the top. Unknown six is ginger ale because it was a positive control during the Benedict's test with sugar being present. Observing the unknown solution, bubbles

were visible. The bubbles represent carbon dioxide, coming to the conclusion it was a carbonated beverage. Discussion: 1. Each test includes a positive and negative control, and two unknowns. The positive control contains the substance of interest and the negative control contains the one without it. The controls aided to clarify the unknowns. The iodine test included water, starch solution, unknown five, and unknown six. Starch reacts with iodine to form a blackish color; if it does not react, it remains yellow-ish brown. The indophenol test included water, ascorbic acid, unknown five, and unknown six. Ascorbic acid bleaches a blue solution of indophenol, turning it colorless. The Benedict’s test included water, sugar solution, unknown five, and unknown six. During the hot water bath, the cupric ions of the reagent are reduced by the sugar to cuprous ions, forming an orangish color. The Biuret test included water, protein solution, unknown five, and unknown six. The copper ions react with peptide bonds to form a pink/purple color; if protein is not present, the solution remains clear. The Sudan IV test included water, vegetable oil, unknown five, and unknown six. Sudan IV is insoluble in water; when mixed with water and oil, it will form a fat layer. 2. Plants store carbohydrates in the form of starch. Iodine test for starch would determine the form of carbohydrate stored in a plant. Iodine does not react with different shaped carbohydrates, so the negative and positive controls in this experiment will provide the answer. 3. There would be no reaction with glycine because the biuret test is used to detect peptide bonds and glycine is the simplest amino acid. 4. Sucrose would be a negative control in Benedict’s solution because it is a non-reducing sugar that does not reduce copper sulphate.

6. During this experiment, there were times when it was hard to see a difference in any of the solutions. Some required more drops of certain controls and more shaking. The accuracy of each test is bothersome because more drops were added to some then what was originally stated in the experiment....