Activity 1: Science Behind Flavor
For week five (5), you will learn more about the chemistry of flavor and the importance of our senses when it comes to determining if something is pleasant/ safe or unpleasant/ unsafe to eat. Why do people have different reactions to the same food? One person may love chocolate while another may find it too sweet. Some people love sour sweets while others find it totally nasty?
Our 5 senses (smell, sight, hearing, touch and taste) help us navigate our environment to keep us safe from danger. Our noses and mouths alert us to things that are harmful or safe for us to eat. Every time you take a bite of food, receptors in your mouth called taste buds pick up the taste of the food you are eating and send a message to your brain. According to current research, scientists believe humans can detect at least five basic taste qualities: salt, sour, sweet, bitter, and umami (savory).
Our sense of taste is greatly influenced by the sense of smell. Over 70% of what we think we taste actually comes from our sense of smell. The nose is equipped with millions of receptors for odor molecules. When we eat, odor molecules (or smells) are released from the food and travel between the mouth and the nose as we chew. The odor molecules meet with the olfactory receptor neurons in the nose and send a message to the brain. The only catch is that air needs to be flowing in or out of your nose for the odor molecules to get into the nose—either through the front or the back. This explains why pinching your nose prevents you from smelling food.
Once they arrive in your nose, odor molecules travel to your nose's olfactory epithelium, the area of the nose where odor detection occurs. While you are eating, your brain receives signals from both your mouth and nose, allowing you to recognize whatever tasty treat you happen to be chewing. In this activity you'll separate the sensations of taste and smell to learn how much each contributes to your recognition of a familiar food.
Essential Concepts:
Areas of focus: Biology, Chemistry
Aim: you will learn more about the chemistry of flavor and the importance of smell and taste.
Materials Needed:
Our 5 senses (smell, sight, hearing, touch and taste) help us navigate our environment to keep us safe from danger. Our noses and mouths alert us to things that are harmful or safe for us to eat. Every time you take a bite of food, receptors in your mouth called taste buds pick up the taste of the food you are eating and send a message to your brain. According to current research, scientists believe humans can detect at least five basic taste qualities: salt, sour, sweet, bitter, and umami (savory).
Our sense of taste is greatly influenced by the sense of smell. Over 70% of what we think we taste actually comes from our sense of smell. The nose is equipped with millions of receptors for odor molecules. When we eat, odor molecules (or smells) are released from the food and travel between the mouth and the nose as we chew. The odor molecules meet with the olfactory receptor neurons in the nose and send a message to the brain. The only catch is that air needs to be flowing in or out of your nose for the odor molecules to get into the nose—either through the front or the back. This explains why pinching your nose prevents you from smelling food.
Once they arrive in your nose, odor molecules travel to your nose's olfactory epithelium, the area of the nose where odor detection occurs. While you are eating, your brain receives signals from both your mouth and nose, allowing you to recognize whatever tasty treat you happen to be chewing. In this activity you'll separate the sensations of taste and smell to learn how much each contributes to your recognition of a familiar food.
Essential Concepts:
- Sense: Is a biological system used by an organism for sensation, the process of gathering information about the world and responding to stimuli. Humans have 5 basic senses: touch, sight, hearing, smell and taste.
- Taste: One of the 5 senses. Taste is caused by chemical substances that stimulate receptors on our taste buds. Humans can detect sweet, sour, salty, bitter, and savory tastes.
- Taste buds: Taste receptor cells that can be found on the surface of our tongue and send information about taste to the brain.
- Smell: One of the 5 senses: Smell is caused by chemical substances that stimulate the olfactory receptors in our nose.
- Olfactory receptor: smell receptor cells that are found deep in the nasal cavity that receive and recognize odor molecules and send information to the brain.
- Odor molecules: smells released from foods
- The sense of smell affects the sense of taste. Our sense of taste can only distinguish between bitter, salty, sweet, and sour.
Areas of focus: Biology, Chemistry
Aim: you will learn more about the chemistry of flavor and the importance of smell and taste.
Materials Needed:
- Jelly beans (at least three different fruit flavors works best)
- Notebook and pen (click here to download results table template)
- A partner. You can also work with a group of friends and compare results
- *Plastic sandwich bags or glasses/ containers
- *Blindfold (optional)
- *Glasses of water (optional)
Procedure/Instructions:
Make sure to perform the activity as a team (parent/grandparent/adult/helper and student). Please read the instructions out loud, and make sure you have all the equipment before you start.
You can try these additional exercises:
Connection to the real world:
Did plugging your nose make it difficult to distinguish a jelly bean's flavor? Could you and your partner recognize a flavor just by sniffing the crushed candies?
When you cannot smell the jelly bean you are eating, you can only taste the candy's sweetness—and that's not enough information to tell which flavor you are chewing. This demonstrates how much we rely on our sense of smell when we "taste" food—much of the experience comes from scents rather than taste itself.
This is also why everything tastes bland when you have a cold - your nose and the olfactory sensors are blocked from receiving signals. In addition to scent and taste, other factors including a food's temperature and texture affect how you experience and interpret each bite.
Food scientists apply this knowledge to develop new flavors and foods. You can also apply this knowledge at home the next time you cook something - can you add an ingredient that makes your food smell good?
You may have heard about people losing their sense of smell and taste after becoming ill with COVID-19. Scientists suspect that the olfactory nerve cells in the nose have been damaged. The vast majority of people recover their sense of smell in two or three weeks.
Make sure to perform the activity as a team (parent/grandparent/adult/helper and student). Please read the instructions out loud, and make sure you have all the equipment before you start.
- Sort your jelly beans by flavor. If you don’t have more than one jelly bean per flavor, cut the jelly bean in thirds with a clean knife (with adult supervision). Aim to have 3 pieces or 3 jelly beans per flavor (2 pieces for tasting, 1 piece to crush up for smelling).
- Ask your partner to close his or her eyes (or use a blindfold).
- Give your partner a jelly bean (or 1 piece). Ask them to chew it and guess its flavor. Record the response, along with the correct answer. Repeat with at least two other flavors. You can offer your subject a glass of water between samples to clean their palate (mouth). How good is your partner at guessing the bean's flavor.
- Tell your partner to pinch their nose shut, then hand your partner a jelly bean (or 1 piece). Ask them to eat the candy and tell you what flavor they taste. Record the response along with the correct answer.
- Repeat the previous step with one or two other jelly bean flavors—you can offer your subject a sip of water in between each to cleanse their palate.
- Record each response, along with the correct answer. Does being unable to smell change your subject's responses?
- With eyes still shut or blindfolded, ask your partner to breathe deeply while you open one of the plastic bags/ containers that hold crushed jelly beans. Ask your subject to guess which flavor they can smell—record the response and correct answer. Repeat with the other two bags. Is your subject better at guessing based on taste alone or scent alone?
- Switch roles with your partner or repeat the above with another subject. Is it easy to recognize the jelly bean flavor by taste? By scent? How do your results compare with your partner's?
You can try these additional exercises:
- You can also try this on different groups of people and see whether certain groups are better than others under different conditions. For example, are older people better or worse at guessing the candy's flavor by scent alone?
- You can try the experiment with apples and potatoes. Peel and chop two potatoes and two apples. (Have an adult supervise when you use knives or peelers.) You'll notice the peeled apple and potato slices look very similar. Hand either a slice of apple or potato to a partner—don't let your partner know which is which. Ask your partner to take a bite while keeping his or her nose pinched closed. Can your partner tell the difference between the apple and the potato? Can you? Try again with the nose un-pinched.
Connection to the real world:
Did plugging your nose make it difficult to distinguish a jelly bean's flavor? Could you and your partner recognize a flavor just by sniffing the crushed candies?
When you cannot smell the jelly bean you are eating, you can only taste the candy's sweetness—and that's not enough information to tell which flavor you are chewing. This demonstrates how much we rely on our sense of smell when we "taste" food—much of the experience comes from scents rather than taste itself.
This is also why everything tastes bland when you have a cold - your nose and the olfactory sensors are blocked from receiving signals. In addition to scent and taste, other factors including a food's temperature and texture affect how you experience and interpret each bite.
Food scientists apply this knowledge to develop new flavors and foods. You can also apply this knowledge at home the next time you cook something - can you add an ingredient that makes your food smell good?
You may have heard about people losing their sense of smell and taste after becoming ill with COVID-19. Scientists suspect that the olfactory nerve cells in the nose have been damaged. The vast majority of people recover their sense of smell in two or three weeks.
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Activity 2: Salad Dressing Science
For week five (5), you will create a simple salad dressing for the plants you grew in Garden in a Glove and learn about the chemistry behind mixtures.
If you’ve ever tried to mix water and oil, you will notice that after a short period of time the mixture separates back into a water layer and an oil layer. No matter how hard you try to shake, stir, or whisk oil and water together, they eventually separate. This happens because water and oil are made of very different types of molecules that are attracted to their own kind.
Many of our favorite condiments (such as mayonnaise) and ranch dressing are created from a mixture of oil and water, but how do they stay mixed together and don’t separate? Introducing emulsifiers! They are like the mediator between two people fighting. While water-based solutions are polar and water loving (hydrophilic) and oil-based mixtures are non-polar (and hydrophobic), emulsifiers contain both hydrophilic and hydrophobic regions and act as the glue to bring everything together. We will use this chemical property to create our own salad dressing that can be used for the plants you’ve grown from Garden in a Glove!
Essential Concepts:
Aim: You will learn how to prepare a simple salad dressing for your plants you grew from Garden in a Glove and learn about the chemistry behind mixtures.
If you’ve ever tried to mix water and oil, you will notice that after a short period of time the mixture separates back into a water layer and an oil layer. No matter how hard you try to shake, stir, or whisk oil and water together, they eventually separate. This happens because water and oil are made of very different types of molecules that are attracted to their own kind.
Many of our favorite condiments (such as mayonnaise) and ranch dressing are created from a mixture of oil and water, but how do they stay mixed together and don’t separate? Introducing emulsifiers! They are like the mediator between two people fighting. While water-based solutions are polar and water loving (hydrophilic) and oil-based mixtures are non-polar (and hydrophobic), emulsifiers contain both hydrophilic and hydrophobic regions and act as the glue to bring everything together. We will use this chemical property to create our own salad dressing that can be used for the plants you’ve grown from Garden in a Glove!
Essential Concepts:
- Polar molecules: molecules that have a slightly negative charge at one end, or pole, and a slightly positive charge at another end.
- Hydrophilic molecule: ‘water loving’. Polar molecules are attracted to water molecules.
- Non polar molecules: neither negatively nor positively charged
- Hydrophobic molecule: ‘water fearing’. Non polar molecules are attracted to other non polar molecules and repel water. Oil is an example of this.
- Emulsifier: A type of molecule that has both hydrophobic and hydrophilic regions and is able to attract and “hold hands” with polar and non-polar molecules, pulling them together to form a special type of mixture called an emulsion.
- Amphiphilic molecule: a molecule has both hydrophobic as well as hydrophilic properties. An emulsifier is an example of this.
Aim: You will learn how to prepare a simple salad dressing for your plants you grew from Garden in a Glove and learn about the chemistry behind mixtures.
Materials Needed:
Make sure to perform the activity as a team (parent/grandparent/adult/helper and student). Please read the instructions out loud, wear safety protection and make sure you have all the equipment before you start.
1. In a clean kitchen space used only for food safe materials, set out your clean containers with clear sides on a stable work area.
2. To one container, add half the packet of oil and half the packet of balsamic vinegar.
3. Stir together with a clean fork for 30 seconds (time it with a clock or stopwatch). At the end of 30 seconds, start the stopwatch again and watch the sides of the glass for 1-5 minutes for signs of separation. Note down how much time it takes for separation to occur in your notebook. This is your control sample.
4. Using your second container, add the remaining oil, balsamic vinegar and honey.
5. Stir together with a clean fork for 30 seconds (time it with a clock or stopwatch). At the end of 30 seconds, start the stopwatch again and watch the sides of the glass for 1-5 minutes for signs of separation. Note down how much time it takes for separation to occur in your notebook. If the mixture has not separated after 5 minutes, write “over five minutes”. This is your test sample.
6. When you are done, you can combine both mixtures together and grab a radish or piece of lettuce and give your emulsions a taste!
Things to think about:
Challenges:
You can try these additional exercises
Connection to the real world:
Understanding polar, non-polar, hydrophilic, hydrophobic and emulsifiers help food scientists and technologists and at-home cooks to create creamy mixtures such as margarine, mayonnaise. Emulsifiers are often added to cakes and bread to keep them moist or greasy.
If you’ve looked at the labels of various dressings and sauces you might have come across the word ’emulsifying agent’ or ’emulsifier’. This is the ‘secret’ to their stable dressings, it’s these components that prevent their mixtures from splitting. Even though their name might sound pretty chemical, emulsifiers have been used for a long period of time and the word emulsifier is simply used to cover a range of different components that all do a similar job: keep two components mixed that don’t want to be mixed.
- Olive oil packet
- Balsamic vinegar packet
- Honey stick
- 2 x small container/ glass (preferably clear)
- Clean fork or something to stir with
- Timer/ phone
Make sure to perform the activity as a team (parent/grandparent/adult/helper and student). Please read the instructions out loud, wear safety protection and make sure you have all the equipment before you start.
1. In a clean kitchen space used only for food safe materials, set out your clean containers with clear sides on a stable work area.
2. To one container, add half the packet of oil and half the packet of balsamic vinegar.
3. Stir together with a clean fork for 30 seconds (time it with a clock or stopwatch). At the end of 30 seconds, start the stopwatch again and watch the sides of the glass for 1-5 minutes for signs of separation. Note down how much time it takes for separation to occur in your notebook. This is your control sample.
4. Using your second container, add the remaining oil, balsamic vinegar and honey.
5. Stir together with a clean fork for 30 seconds (time it with a clock or stopwatch). At the end of 30 seconds, start the stopwatch again and watch the sides of the glass for 1-5 minutes for signs of separation. Note down how much time it takes for separation to occur in your notebook. If the mixture has not separated after 5 minutes, write “over five minutes”. This is your test sample.
6. When you are done, you can combine both mixtures together and grab a radish or piece of lettuce and give your emulsions a taste!
Things to think about:
- Out of the ingredients listed above, can you guess which ingredient is the polar molecule (hydrophilic), which ingredient is the non-polar molecule (hydrophobic), and which ingredient is the emulsifier?
- Did the mixtures with the emulsifier take more or less time to separate than your control? Is this what you expected?
- Lemon juice is mostly citric acid and water. Would you expect it to mix better with olive oil or vinegar? Why or why not?
- Look for recipes for other salad dressings or vinaigrettes online. For each, try to identify which ingredient is the polar molecule (hydrophilic), which ingredient is the non-polar molecule (hydrophobic), and which ingredient is the emulsifier.
Challenges:
You can try these additional exercises
- You can repeat steps 1-5 to try out other herbs or spices, such as salt and pepper, to see how they effect the separation time of your dressings. You can also experiment with other vinegars or oils to see how their separation times differ, or investigate the effect of temperature on separation time.
Connection to the real world:
Understanding polar, non-polar, hydrophilic, hydrophobic and emulsifiers help food scientists and technologists and at-home cooks to create creamy mixtures such as margarine, mayonnaise. Emulsifiers are often added to cakes and bread to keep them moist or greasy.
If you’ve looked at the labels of various dressings and sauces you might have come across the word ’emulsifying agent’ or ’emulsifier’. This is the ‘secret’ to their stable dressings, it’s these components that prevent their mixtures from splitting. Even though their name might sound pretty chemical, emulsifiers have been used for a long period of time and the word emulsifier is simply used to cover a range of different components that all do a similar job: keep two components mixed that don’t want to be mixed.
|
Post your results on our Flipgrid page for your chance to enter our weekly prize draw!
Guest password: ETHOS2021 Click here |
