Biology Milk Lab

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Bonnie Bell

Mrs. Legary

Biology P.6

21, Sept. 2011

Milk Lab Final

This investigation consists of testing the reaction between milk, food coloring, and dishwashing soap. Different kinds of milk were tested, depending on the amount of milk fat content. The investigation was based on 2 questions. Lab one’s problem statement, using only milk fat and food coloring was: How does food coloring react in different kinds of milk fat? The second lab’s problem statement, using milk fat, food coloring, and dishwashing soap was: What happens when detergent is added to different milk fats and food coloring? The expectation is that the milk with higher fat content will have a more dramatic reaction. If the milk has a higher fat content, then the reaction of food coloring and dishwashing detergent will be more dramatic because there are more molecules to interact with each other.

Since milk is made up of many parts that are attracted to some substances and repel others, it causes a reaction when coming into contact with other substances such as dishwashing detergent and food coloring. Fats and proteins, which milk is filled with (depending on the type of milk) are sensitive to changes in the surrounding solution. Dish soap weakens the chemical bonds that hold the proteins and fat in the solution. Since the food coloring dropped in the milk is made of mostly water, it doesn’t have a big effect on the milk. But when dish soap is added, the milk fat molecules move around in all directions, and the soap molecules race around to join the fat molecules. During this reaction, the food coloring molecules are moved everywhere, causing you to be able to see the reaction. The higher the milk fat, the better the reaction the soap has with the milk.

The controlled variables for this investigation were:
- Amount of milk
- Amount of food coloring
- Dish soap

The manipulated variable was:
- The different kinds of milk fat
-Whole milk, 1%, fat free, half & half, and heavy whipping cream

The responding variable is:
- The reaction of the food coloring to the milk fat and dishwashing soap.

- 4 petri dishes
- Whole milk, fat free milk, 1% milk, and half & half
- Red, blue, green, and yellow food coloring
- Toothpicks
- Dishwashing detergent

1. Make a data table
2. Get 4 Petri dishes
3. Pick 4 kinds of milk
4. Pour each kind of milk in 4 different labeled dishes
5. Each person put a drop of one red, blue, yellow, or green in each petri dish 6. Watch and record the reaction in the data table
7. Make a new data table
8. Repeat steps 2-5
9. Add a drop of dishwashing detergent into each petri dish
10. Repeat step 6 in new data table
The procedure steps in this investigation were repeated 7 times.

The first Experiment we did, we took 4 petri dishes and filled them each with a different

kind of milk fat. Then in each dish, we put one drop of each food coloring in it. Each dish had a

different reaction to the food coloring, which was recorded in the data table. Then we did the

same experiment again, but we also added a drop of detergent to each one. Then we watched the

reactions and recorded the results in the second table.

Day 1 data – no detergent

|Food Coloring |Milk fat 1 |Milk fat 2 |Milk fat 3 |Milk fat 4 | |Red |Spread fast and wide |Spread fast and wide |Spread slow in an oval |Didn’t expand very big | |Blue |Slow. The color stays dark |Spreading fast. One big |Looks spider web-ish. Starts|Color gets lighter as it | | |and keeps expanding |glob. Keeps expanding |light, expands darker slowly|expands | |Yellow |More spread out |Stays in a little circle |Stayed in a little circle. |Stayed in a small...
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