Lab 1: Lipid Language

Teacher Preparation:

1. Review information found in the Background Agricultural Connections section of the lesson, lesson Procedures, and the attached Essential Files.
2. Assign each student group 1 fat type (butter, margarine, or oil).
3. Note that the teacher demonstration will show students the temperature and time it takes for two types of solid fat (i.e. butter, margarine) to melt. After melting the solid fats, you will divide each liquid fat evenly between two small, clear plastic cups.
4. Distribute assigned liquid fats to student groups. Student groups will need to observe the liquid fats as part of the “cold treatment” procedure.
   • Timesaver: Use the demonstration video in place of the in-class teacher-led demonstration. Provide students with the data below after your class has viewed the video. 

• Note: The temperatures below are higher than the melting points described in the background. The temperature of the melted butter and margarine were measured after the products had completely melted, resulting in an overall higher temperature.

Procedures:

1. Consider having your students research the types of lipids (fat), their role in the body, their dietary sources, and the health benefits/consequences of consuming them prior to beginning the lab investigation.
2. Distribute lab materials. It is recommended that materials are organized into stations for easier distribution. Students should be arranged in small groups of 4-5. Each group should receive the lab supplies outlined in the Materials section as well as 1 copy of the Lipid Language lab sheet and one copy of the Fatty Distinction student handout.
3. Ask students to read Fatty Distinction and complete the focus questions for this lab investigation.
4. Before beginning the lab investigation:
   1. Require students to wash their hands.
   2. DO NOT allow students to taste the lipids featured in this lesson. Students will be given the opportunity to taste a healthy fat (olive oil) in Lab 2: Lipid Language.
   3. Emphasize the importance of practicing good food safety behaviors by not consuming substances used as part of the lab investigation.
5. Begin the student lab investigation by asking students to make a prediction about the rate different fat types melt and solidify. You may also choose to show the provided video lab demonstration, Food Explorations Lab I: Lipid Language. The video will help students understand the procedures and visual observations. 
6. Launch the teacher demonstration. The demonstration will show students how to find the melting points of butter and margarine. For an in-class demonstration use the following steps:
   1. Demonstrate for students how to find the melting points of butter and margarine. Vegetable oil will not undergo heat treatment because it is already a liquid at room temperature.
   2. Add 1/2 cup of cold butter to a saucepan and 1/2 cup of cold margarine to a second saucepan. You may choose to heat one fat type at a time or ask for student assistance. The solid fats may take slightly longer to melt due to the use of a double burner versus conventional stovetop.
   3. Once each solid fat is added to the saucepans, the stopwatch should be started to ensure accurate recording of the amount of time it takes each fat to turn into a liquid.
   4. Continue to heat each fat type on medium heat until it is completely melted. Once each fat has completely melted, the time and temperature should be taken.
   5. Record the time it took to melt each fat type in a place visible to students. Students should record this data in Table B under the column labeled “Heat Treatment.”
   6. Measure the temperature of each melted fat type and record the data in a place visible to students. Students should record this data in Table B under the column labeled “Heat Treatment.”
   7. Pour 1/4 cup of each melted fat type into a separate plastic cup to be used for student observation later in the lab investigation.
7. After the teacher demonstration, students will complete the procedures for “cold treatment” with their assigned fat type. Once the fats have been submerged in ice, the solidification process takes approximately 10 minutes.
8. Students should find the following results:
   1. Butter: Butter represents a saturated fat. During heat treatment, the butter will melt more slowly compared to margarine; however, it will be completely melted at a lower temperature. During cold treatment, the butter will solidify at a lower temperature compared to the margarine.
   2. Margarine: Margarine represents a trans fat. During heat treatment, the margarine will melt and reach a higher temperature more quickly compared to the butter. During cold treatment, the margarine will solidify at a higher temperature compared to butter and oil. When a cis fatty acid is converted to a trans fatty acid, the carbon chain is lengthened. Therefore, solid fats that contain trans fatty acids will have higher melting points. These fats also tend to be more solid at room temperature compared to their cis counterparts (e.g. olive oil, vegetable oil). Newer food technologies have been implemented that reduce or remove the production of trans fatty acids in food products such as margarine; however, it is important to look at the food label to determine if a food contains trans fat (see Fascinating Fats activity in the Interest Approach).
   3. Oil: Vegetable oil contains unsaturated fat and has a lower melting point. The oil is already liquid at room temperature. Additionally, the oil will not solidify during cold treatment, but rather take on a cloudy appearance. Oils are unsaturated fats, meaning the carbons within the fatty acids are not completely saturated with hydrogen.
9. Allow students to work in small groups on the Lipid Language lab sheet to further explore the topic and respond to lab questions.
10. Follow-up with a class discussion about sources of different types of dietary fat in real life, and the relevance to overall health and energy balance. See Enriching Activities for ideas on how to further extend this lesson.

Lab 2: Examining Emulsions

Teacher Preparation:

1. Consider having your students research the types of lipids (fat), their role in the body, their dietary sources, and the health benefits/consequences of consuming them prior to beginning the lab investigation.
2. Prepare materials for each group. To prepare mixtures, each group will need 5/8 cup of vinegar and 5/8 cup of olive oil. Each student group will also need 1 teaspoon of each treatment (ground mustard, honey, paprika, and salt).
3. Consider placing materials in organized stations around your classroom. Allow students to visit organized stations to retrieve needed lab materials.
   • Timesavers:
     • You are encouraged to allow students to measure out their own treatments; but if time is a concern, pre-measuring treatments is recommended.
     • Another option is to have each group make 5 jars of the same treatment. Jars can then be exchanged among groups. Another option is to assign four students to rotate around the room delivering each of the four treatments to student groups.
     • If you chose to allow students to participate in the optional lesson extension, pre-focus the microscopes to save time.
     • If limited sink space is available, place pans or buckets of warm, soapy water and rinse water around the classroom so jars can be sufficiently cleaned for another class. Another option is to consider using disposable containers so that you can easily discard the mixtures after completing the lab.

Procedures:

1. Consider having your students research common mixtures (e.g. homogeneous, heterogeneous) that can be eaten prior to beginning the lab investigation.
2. Distribute lab materials. It is recommended that materials are organized into stations for easier distribution. Students should be arranged in small groups of 4-5. Each group should receive the lab supplies outlined in the Materials section as well as 1 copy of the Examining Emulsions lab sheet.
3. If students did not complete Lab 1, ask students to read the Fatty Distinction student handout and complete the "Think About It" questions for this lab investigation.
4. Before beginning the lab investigation:
   1. Require students to wash their hands.
   2. Emphasize the importance of practicing good food safety behaviors by not consuming substances used as part of the lab investigation.
   3. Note that students should be allowed to taste their final product as part of the lab investigation.
5. Launch the student lab investigation by asking students to make a prediction about the emulsification abilities of common household ingredients.
6. Show students the provided video lab demonstration, Food Explorations Lab II: Examining Emulsions. The video will help students understand the procedures and visual observations. Students should observe the following: 
   • The ground mustard should serve to emulsify the vinegar and oil. Ground mustard serves as an emulsifier because it contains protein, carbohydrate, and lipid in its seed. The protein and carbohydrate molecules are hydrophilic (water soluble), while the lipid molecules are hydrophobic (fat soluble). This unique combination of molecules enables ground mustard to aid in the creation of a homogenous vinegar and oil mixture. Egg yolks are another common food-based emulsifier.
   • Honey, paprika, and salt are not emulsifiers. None of these ingredients will prevent the oil and vinegar from separating (heterogeneous mixtures). However, when the students combine the mixtures, the vinaigrette should create a homogeneous mixture due to the presence of the ground mustard.
7. Allow students to work in small groups on the Examining Emulsions lab sheet to further explore the topic and respond to lab questions.

Optional Lab Extension:

1. Launch the lab extension by allowing students time to observe a fat emulsion under the microscope.
2. Follow-up with a class discussion about unsaturated dietary fats (e.g. olive oil) and their health benefits. See Enriching Activities for ideas on how to further extend this lesson.