Chemistry of Cooking

Strategies and Activities

This unit will be integrated into my chemistry curriculum.  Throughout the school year my students keep a single notebook in which they record all notes and data. Each grouping of notes includes a major heading and a date. Most students keep their notebooks in the classroom but any student is welcome to take it home. (I like to give my students the option to reduce the chance of them losing the notebook.)  For this unit, the students should have headings similar to the headings provided for each lesson.  The thought behind the notebook is that at the end of the year it will become their personal arsenal of information that they can use to study for the  Virginia Chemistry Standards of Learning assessment. Furthermore, each lesson will include an interactive portion to allow the students time to process and practice the information/concept taught to them.  To better scaffold the instruction, I prefer to use a modified version of the I Do, We Do, You (They) Do model.  During the “I Do” portion of the class period, direct instruction is given while the students listen and take notes.  The “We Do” portion is an interactive instruction period for an assignment, where I prompt them with questions, walk around, check work, and give additional information and help.  In the “You Do” portion, students either work independently or collaboratively on an activity with minimal help from me to help me better determine their level of understanding. In using this model approach, you will encounter the following strategies throughout each lesson: effective questioning, collaborative learning groups, progress monitoring, direct instruction with teacher guided note-taking, hands-on learning, debating, nonlinguistic representations, notebooking, and field experience/trip.

Lesson 1: What is flavor?

Warmup: When the students walk through the door, I will give them a piece of fruity candy and a half sheet of paper; then ask them to write a detailed description of the candy.

I Do: After the warmup, I will ask the students what observations they made about the candy.  Students will give their responses and I will explain the difference between observations and inferences.  Then I will ask the students if they have ever thought about how we smell or why our tastes seem to change when we have a cold.  At this point, they should be intrigued and either shouting out possible answers or waiting for the explanation.  This is the time when I will introduce the idea of flavors as chemicals.  Through direct instruction, I will explain how flavors are made of molecules, as well as explain the bonding types and the properties of each.  My students do well with hand drawn visuals so I will also draw out atoms to show how the electrons are moving.

We Do: We will color in individual periodic tables identifying the metals and nonmetals and how to use the periodic table to identify each type of bond within a molecule.  We will watch a video⁴ on ionic and covalent bonding and I will clarify any misunderstandings.  I will then aid students through a collaborative card sort activity (refer to Activity 1) on the properties of ionic and covalent compounds.

You Do: The students will complete a worksheet (refer to Activity 2) individually identifying covalent and ionic compounds while I walk around checking for understanding.

Activity 1: Card Sort (refer to Figure 6): For this activity, I will pre-cut each card, mix them, and place the mixed set in a resealable plastic bag.  My room is set up with 4-person tables. There will be enough sets printed for each table.  The student will separate the cards into two groups; one ionic and the other covalent.  I will circulate around the room giving hints when needed.  Once each table has all of their cards sorted correctly, I will then post the answers and have the students write them as part of their notes for the day.  Each student will make two columns and list each component identifying an ionic compound and each identifying a covalent compound.

Activity 2: Worksheet (refer to Figure 7): The student will complete a worksheet in which they will be able to show their knowledge of ionic and covalent compounds independently.  The first part of the worksheet, they will identify the bonding type of the compounds by identifying whether the two elements being bonded are a metal and non-metal (ionic) or two non-metals (covalent).  The second part of the worksheet asks the student to calculate the difference in electronegativities of the two elements presented and then to determine whether they bond ionically or covalently.  Each student will have a periodic table of electronegativities available.

Takeaway:  I want my students to leave the class thinking about ionic and covalent compounds.  I want them to begin to identify with the chemistry in their lives.  My thought is that they will be at home, glance over at the salt and think to themselves “That’s an ionic compound”.

Figure 6. Card Sort

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Figure 7: Worksheet

Name____________________________________ Date______________  Class Period______

Determine the electronegativity difference and the probable bonding type.

Lesson 2: How our body processes flavor

Warm up:  Students will be given a list of several molecules and asked to identify all of the ionic compounds.

I Do:  I will go over the warm up, then introduce some the key identifying components of molecules.  This is the point when I will discuss NCHOPS (refer the section on Chemicals in Flavor), what the word organic means (in chemistry), and how essential carbon is to human life and our food.  During this portion, students will also follow my lead and take notes on what a functional group is and identify the four main groups I mentioned earlier in the unit. Taste and smell receptors will also be discussed.

We Do:  We will watch a video⁵ on flavor chemistry and discuss functional groups further. I will give each table a structure of a protein, a carbohydrate, and a fat.  They will be assigned to circle all of the functional groups they see in each and identify the name of the group. 

You Do: The students will do a paper domino activity (refer to Activity 3).

Activity 3: Domino activity (refer to Figure 8):  I will have the dominoes already pre-cut, mixed, and put into resealable plastic bags.  The objective is for the student to match the ends of the domino with its corresponding answer. If done correctly, the corresponding answer on the last domino will match the first domino.

Takeaway: This lesson is meant to get them thinking about what they are eating and how their bodies are interacting with the food.   From this lesson, they will see how closely biology relates to chemistry and be able to identify functional groups.

Figure 8: Domino Activity

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Lesson 3: natural versus artificial flavors

Warmup: The students will be asked to define what they think a natural flavor is and what an artificial flavor is on separate sticky notes. I will also have them write their names on the back of the sticky as a quick participation grade. They will then place the sticky notes on the white board underneath the correctly labeled column of either Natural or Artificial.  I will review the posted answers and read all or a few of them depending on how large the class is.  I like to use this strategy in the beginning of the year because my students are not yet as open about sharing information but it is important to me to find out what they already know about a topic.  One way I do this is by having them share information on a sticky note and, instead of having them read it, I read it and share it with the class.  That way no one is singled out and I can still have a mental assessment of what they know.

I Do:  I will show the students the FDA definition of a natural and an artificial flavor.  From this I will have the students help me write our own definition of each.  Then I will explain what a debate is, as well as explain the guidelines of our class debate.

We do/ You do:  Each team will read their articles.  I will give them guiding questions of what to look for in the articles.  Then we have a town hall style debate (Activity 4).

Activity 4: Town Hall Debate:  This activity may expand over two class periods. (1) Separate the class into 4 teams. (2) Determine ahead of time the 4 articles that will be used for the debate.  The two debating sides are the Naturalists (anti-artificial flavors) and the Flavorists (pro-artificial flavors).  Each team will be given different articles to read but two of the articles should lean more against artificial flavoring and two more in flavor of artificial flavoring. (3) Have the students read the article to themselves and then discuss what they read with their team.  During this discussion, they should determine 2-3 main points they determined from the article and then highlight facts and supporting information to back up their claim.  (4) Have each team choose one person to summarize the article to the class.  The person summarizing will mention the main points of the article as well as any supporting information from the article. When that person is speaking there should no interruptions but students are allowed to take notes and write down questions for the opposing side.  (5) After all summaries have been made, all other students now have the opportunity to comment and ask questions by raising their hand.  They are encouraged to provide supporting information from their reading or reputable sites to rebut or support any information mentioned in the summaries.  Extra points will be given to teams who have whole group participation and who show respect for the other teams. (6) At the end of the discussions, allow student time to reflect on the topic by writing their answers to the following questions:  What did you like about participating in the debate? What was the most interesting argument presented? In what ways do you think a class debate helps you in real life situations? Did you ever think about where the flavor came from in your foods before this debate? Has your viewpoint changed about artificial flavors?

Takeaway: I want the students to leave the classroom knowing that they can effectively communicate their viewpoints and ideas without arguing. Also, I hope that this lesson encourages them to think before they speak and to find camaraderie in working as a team.  This lesson will teach them how to construct and defend a scientific viewpoint.

Lesson 4: Flavor extracts and Enhancing flavor

Warmup:  I will give each student two pieces of the candy, preferably the same flavor.  However, one piece will be made with all-natural flavors and the other with artificial flavor but the students will not know.  They are then to vote on whether Candy 1 or Candy 2 was more flavorful.  Then I will reveal to them the difference between the candies.

I Do:  I will go into notes on extracts.  I will discuss what an extract is and what the process of extraction means in chemistry.  I will then discuss flavor extracts and present the students with a question, asking them to give me some examples of flavor extracts they have seen being used in their homes. I will also ask what are some other things that we do to our food to enhance its flavor and discuss ways to enhance flavor. 

We Do/ You Do:  We will make salsa (refer to Activity 5).  We will discuss each ingredient and what flavor it adds to the dish.  I will review the chemistry of some of the ingredients. 

Lesson extension:  To extend the lesson or to add further enrichment for my honors students, I may also discuss esterification reactions to build on how flavors are made.  This added information will give us the opportunity to go over the functional groups found in organic compounds, as well as discuss reversible reactions and use of catalysts.

Activity 5: Making Salsa (a Teacher demo): Part 1-  Ahead of time will have prepared some tomatoes mixed with onions that have been refrigerated overnight.  I will place 2-3 pieces of just the tomatoes in small cups for each student.  I will announce that I mixed the tomatoes with one ingredient, left it overnight and then removed that ingredient. I want the students to try to determine what the missing ingredient is.  My thought for this is that it will help the students get a better understanding of extractions.  The reason they can still smell or taste the onion without it being there is because those flavor chemicals have been extracted from the onion into the juice of the tomatoes.

Part 2- Ahead of time I will precut all ingredients.  I will let the student determine what ingredients might represent each of the 5 basic tastes.  My recommendations are mango-sweet, salt-salty, limes-sour, cilantro and raw onion-bitter, and tomatoes-savory.  I will make a class batch of salsa leaving out the mango and jalapeños for students to add themselves as they please.  The students will then be allowed to eat the salsa while I will give a little background and chemistry about each ingredient.  I will discuss why spicy is not a taste.  Spicy foods contain capsaicin which triggers our pain receptors.  We do not have a spicy taste receptor.  What we call spicy is simply a trick of our minds into thinking we are experiencing heat or a burning sensation. 

Takeaway:  I want my student to leave aware of how everyday things such as making salsa reinforce chemistry concepts.

Lesson 5: Lab Day- Making an Extract

Warmup:  When the students walk into the classroom, hand them an MSDS (Material Safety Data Sheet) of ethanol (the alcohol used in the lab for day) and provide them several questions written on the board. They will have to read through the MSDS to find the answers.  Then as a class discuss the importance of a MSDS and what it tell us about the chemical we are using.

Lab 1:  Make an extract: Students will be divided into groups of 3-4, reminded of the safety procedures, and given a lab sheet to prepare their extract (refer to Figure 9).  The plants I have chosen are ones that have a shorter steeping time.  They are mint, lemon, lime, lavender, orange, and ginger.  I will also purchase a bottle of Sauer’s vanilla extract because vanilla beans take longer to steep than the time available.  (1) Groups who choose mint and lavender will use scissors to cut up the flowers and leaves into small pieces.  For groups who choose a fruit, only the zest is being used and I will provide a zester for those groups. I will also precut the ginger ahead of time. (2) Students should cut or zest enough of the plant or fruit to fill ½ the jar.  Then use weighting paper to weigh the herb in grams and place it into the jar.  (3)  The students are to measure out 50 mL of the alcohol/water solution (vodka) and pour enough into their jar to completely cover the herbs.  Remind the students of the correct way to read a graduated cylinder.  They will have to determine the volume of solution used if the entire 50 mL was not used or if more than the 50 mL was required. (4)  Student need to determine their weight to volume ratio (g/mL). (5) Prepare a water bath and have the students use a thermometer to read and record the temperature of the water. Then have the student place their jars in the warm water for 10 minutes to help reduce the steeping time.  Have them read the temperature again after all the jars have been added.  Talk about the movement of heat.  (6) Remove from the warm water and let the mixture sit for 2-3 days.  Have students shake the jars daily.  (7) When the extracts are done, the student will perform out a filtration.  Using cheese cloth and a funnel, they will filter out the liquid from the solid plant matter into a clean glass jar.

Takeaway:  From this lesson, I want my students to have a better understanding of safe lab practices, procedures, and techniques.  They will leave knowing how to read hazard warning labels and basic lab equipment and their uses.

Figure 9: Extract Lab

Making an Extract

Names of group members: ________________________________________________

Name of the plant or fruit: ____________________ Date of production: _____________

1. Cut (with scissors provided) or zest enough of the plant or fruit to fill ½ the jar. Then use weighing paper to weigh the herb in grams, record your mass in the table, and place it into the jar.
2. Measure out 50 mL of the ethanol/water solution and pour enough into their jar to completely cover the herbs. You do not have to use it and you may add more if needed.  Then record the volume of solution used.
3. Determine their weight to volume ratio and record it in the table.
4. A water bath has been prepared. Twist the lid on tightly and place the jar in the warm water for 10 minutes.
5. Remove the jar from the warm water and let the mixture sit for 2-3 days. Shake the jar daily. 
6. When the extracts are done, we will perform out a filtration using cheese cloth and a funnel to filter out the liquid from the solid into a clean glass jar.

Lesson 6: Lab Day- Making a bath salt scrub

Warmup: This is a great point to talk about the C. F. Sauer company. I will display a photo of the Sauer’s sign and ask the students if have they ever seen the sign and where.  We will discuss the history of the company, its importance to Richmond’s history, and products they own.  Then I will have them check on their extracts and filter them.

Lab 2: Make a bath scrub: After all extracts have finished steeping (2-3 days), explain to students that body scrubs remove dead skin cells from the body through exfoliation and help increase circulation.  By doing this, we are able to absorb moisturizer more easily.  This in turn gives off a fresher more radiant appearance by reducing dark spots from acne and preventing ingrown hair; something all teenagers can relate to.  (1) Have each student determine if they want to make a (white)sugar scrub or an (Epsom)salt scrub, then have them measure or weigh out a predetermined amount and place in their individual plastic container.  (2) Then have the student add half the amount of olive oil to the solid material in the container.  For example, if 2 cups of sugar were used then add one cup of olive oil. (3) Lastly, have the students add 10 drops of one of their extracts or 5 each of two different extracts., stir with a spoon and let them try it out on their hand at the sink. Explain to student not to rub to hard when using their scrub and to not use it all if they have a rash or a skin condition.

Takeaway:  I believe that many of my students will be shocked to learn that Sauer’s was founded in Richmond and is still an important part of Richmond.  Perhaps that could turn into a field trip. Also I want my students to know how to carry out a filtration and when to use filtration as the separation technique of choice.

Lesson 7: Unit Assessment

The assessment will cover identifying functional groups, explaining a filtration, how to respond in an emergency situation based on a MSDS, safe lab practices, instruments to measure temperature, volume, and mass, and identification of bonding types.