Procedure
Iodine Test (starch):
Benedict’s Test (Reduced Sugar):
Biuret Test (Proteins):
Sudan III Test (Fat & Oil):
****Wash the test tube with deionized water before reusing it while performing the lab****
PART A
PART B
PART C
- Add 1 mL (20 drops) of iodine solution into the test tube containing the food being tested with a pipet and observe.
- If Positive: a dark blue color appear---there is starch in the food being tested.
- If Negative: no color change---no starch in the food being tested.
- Record observations on the data table.
Benedict’s Test (Reduced Sugar):
- Take a 250 mL beaker, fill the beaker halfway full with water and put a boiling stone inside the beaker; put the beaker on a hot plate with medium setting and let it boil.
- Add 2 mL of Benedict's solution into the test tube containing the food being tested with a pipet and observe.
- If Positive: Color changes, can change into a variety of colors (blue, green, yellow, red)---there are reduced sugar inside the food being tested.
- If Negative: No color changes---No reduced sugar inside the food being tested.
- Record observations on the data table.
Biuret Test (Proteins):
- Add 1 mL (20 drops) of Biuret solution into the test tube containing the food being tested with a pipet and observe.
- If Positive: a purple color appear---there is protein in the food being tested.
- If Negative: no color change---no protein in the food being tested.
- Record observations on the data table.
Sudan III Test (Fat & Oil):
- Add 1 mL (20 drops) of Sudan III solution into the test tube containing the food being tested with a pipet and observe.
- If Positive: a grease layer can be observed---there is fat/oil in the food being tested.
- If Negative: no any kinds of layers, everything is mixed together---no fat/oil in the food being tested.
- Record observations on the data table.
****Wash the test tube with deionized water before reusing it while performing the lab****
PART A
- For Glucose, do the Iodine test, Benedict’s test, Biuret test, and Sudan III test and record observations and results in Data Table.
- For Fructose, do the Iodine test and Benedict’s test, and record observations and results in Data Table.
- For Starch, do the Iodine test, Benedict’s test, Biuret test, and Sudan III test and record observations and results in Data Table.
- For Albumin, do the Iodine test, Benedict’s test, Biuret test, and Sudan III test and record observations and results in Data Table.
- For Gelatin, do the Biuret test and record observations and results in Data Table.
- For Corn Oil, do the Iodine test, Benedict’s test, Biuret test, and Sudan III test and record observations and results in Data Table.
- For Olive Oil, do the Sudan III test and record observations and results in Data Table.
PART B
- Do all four tests (Iodine test, Benedict’s test, Biuret test, and Sudan III test) for Milk, Egg White, Apple Juice, and Potato Flakes.
- Record observations and results in Data Table.
PART C
- Put some low-fat/zero-fat margarine, regular butter, and salad Dressings into separate test tubes and do the Sudan III test for the three products. **Melt the margarine and butter with a hot water bath.
- Tear a piece of bread and do the Iodine test on it; record the result on the Data Table
- Take a piece of apple/banana, put it into mortar and add 10 mL of water and mash them together, and do all four tests (Iodine test, Benedict’s test, Biuret test, and Sudan III test) with the two fruit mashes.
- Take different kinds of sugar and do Benedict’s Test on them; record the results on the Data Table.
- Take your favorite kinds of cereal and do Benedict’s test with it.
- Take some avocados and mash it and do Sudan III Test with it and record the result on the Data Table.
RESULT
Part C
Note: In Part C, (+) = positive, and (-) = negative
Overall, most of the results were expected. Substances like glucose had sugar, and starch obviously had starch in it. The most interesting results came from Part C, where everyday foods and variances on butter and sugar were tested.
Overall, most of the results were expected. Substances like glucose had sugar, and starch obviously had starch in it. The most interesting results came from Part C, where everyday foods and variances on butter and sugar were tested.