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Nov 12, 2021

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Page 1: stem.nmsu.edu STEM Outreach stem nmsu stem nmsu ...

stem.nmsu.edu STEM Outreach Center-NM

stem_nmsu stem_nmsu stemoutreachnmsu

Page 2: stem.nmsu.edu STEM Outreach stem nmsu stem nmsu ...

The Science of Cheese!

Ingredients

1. a serving of cheese to examine and enjoy! I suggest string cheese!

The Chemistry of Cheese!

“Cheesemaking is the controlled process of removing water from milk. This process concentrates the milk’s protein, fat and other nutrients and increases its shelf life.” “Cheesemaking is one of the earliest examples of biotechnology.”Biotechnology stands for biological technology. This is advanced science that produces using biological chemical reactions and changes. “Cheesemaking is an ancient biotechnology that dates back to the domestication of animals. It is thought that it was probably first discovered by observing the accidental souring of milk and then pressing and salting the solid curd to preserve it for later consumption.”“Cheesemaking involves coagulating [thickening] the protein in milk and then separating the milk into solid curds and liquid whey. The liquid whey is drained away, and the curds are salted, shaped and left to ripen in a controlled environment.”“Microorganisms are used in each step of this process and determine the flavour and texture of the final cheese.”Want to know more? Cheese really is amazing! Visit the webpage below and watch their videos to learn a more in-depth explanation of how exactly cheese is created using chemical reactions and micro-organisms! It will really open your mind to the amazing science of cheese. Enjoy!

Science courtesy of “The Science of Cheese” by the New Zealand Science Learning Hub ( https://www.sciencelearn.org.nz/resources )

https://www.sciencelearn.org.nz/resources/827-the-science-of-cheese

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Candied Fruit (Tanghulu)!

Ingredients

1. 2 cups of sugar2. variety of fruit of your choosing* 1 1/3 cups of water (free ingredient)

Procedure

Pour 2 cups of sugar into a sauce pan. Add 1 1/3 cups of water to the sauce pan with the sugar. If you have a candy thermometer bring it out, but it is optional. You want to place the candy thermometer in the sauce pan to register the temperature of the liquid at 260-265 degrees Fahrenheit. Turn the heat on medium and use a spoon to mix the sugar and water until the sugar dissolves into the water. Allow the liquid to heat up until the majority of the water dissolves, leaving us with a clear syrup. If you have a candy thermometer, the temperature should be between 260-265 degrees Fahrenheit. Turn the heat off. You have just made a sugar gloss! You can spoon this over any fruit and make a hard, crunchy coating for old fruit you might have around the kitchen. Be sure to dip your fruit in using a BBQ skewer or long fork, etc. to avoid getting a burn!This activity should only be completed with adult supervision and adult help. Enjoy your crunchy snack!

Adapted from “Tanghulu” (https://www.easychineserecipes.com) and The Renegade Kitchen (http://www.renegadekitchen.com/)

The Chemistry!

Why does the mixture of water and sugar create a runny liquid that gets hard as soon as it touches fruit or other food objects?

When we mix sugar with water, we are creating something called a solution. The sugar dissolves in the water, and it cannot be separated. The sugar molecules are suspended (floating) in the water. We now heat up the sugar-water solution, which causes the sugar molecules to melt inside of the water and create a sugary syrup. While hot, sugar becomes viscous (runny and water-like). Sugar is normally a solid and a crystal at room temperature. When you dip your fruit into the syrup and bring it out to place on a plate or parchment paper, the solution quickly cools. This causes the sugar crystals to return to their solid/crystal state and the remaining water is trapped in the solution. The result is a hardened sugary coating around your fruit.The hard sugar coating is delicious and is a great idea to use with fruit that you may have purchased that did not turn out to be as sweet as you thought it would be.Candied fruit are called “tanghulu” or “bingtangulu” and the idea comes from ancient China. Cool! “Tanghulu” in Chinese means “candied”! Enjoy!

Procedure

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Icebox Pie!

Ingredients

1. two 14-ounce cans of condensed milk2. ¾ cup of lemon juice3. 1 prepared crust made from graham crackers or whatever you have on hand

Procedure

Pour two cans of condensed milk into a bowl. Measure ¾ cup of lemon juice and mix into the condensed milk. Mix well, watching as the filling becomes creamy and coagulated (thicker).Pour filling mixture into your prepared graham cracker crust. If you do not have a crust, you can also place leftover cookies in the bottom of a dish and then pour the mixture over it. Refrigerate overnight or up to 24 hours! The more time you leave it in the fridge, the stiffer it will get!If you use whole lemons to extract your lemon juice, feel free to add lemon zest to your pie or cut a small slice of lemon wedge to decorate your icebox pie with!Cut a slice and enjoy! The perfect summer dessert!

Recipe courtesy of #EmmyMadeinJapan on Youtube™ Check out her channel!

The Chemistry!

Why does the pie filling get stiff without having to be baked? How does the filling go from runny to stiff?

Lemon juice is acidic. This means that the molecules inside of the lemon juice are strong and grab onto other molecules willingly!Condensed milk is fatty and the molecules are chunky! When the two items (lemon juice and condensed milk) are mixed together, the acids in the lemon juice react with the proteins in the milk, which causes the milk to thicken! The structure of the milk is changed and becomes heavier because molecules are grabbing onto one another in their excited state! This causes a texture that is similar to pudding or cheesecake filling!Chemical reactions are awesome! This one is very easy to see as you create your icebox pie, so be sure to watch carefully, as the chemical reaction happens very quickly!

Procedure

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Vanilla Ice Cream!

Ingredients

1. 2 cups heavy whipping cream2. 2 cups half-and-half cream3. 1 cup of sugar4. 2 teaspoons vanilla extract

Procedure

Place a shallow glass or metal container into a freezer 2 hours before you make your ice cream. Combine the heavy whipping cream, half-and-half cream, sugar and vanilla extract in a bowl, stirring to make sure the sugar dissolves completely. Pour your ice cream mixture into the previously chilled shallow container.Store your ice cream in the coldest part of your freezer until almost firm, but soft enough to be stirred. Check your ice cream every 30 minutes for 3 hours, mixing it with a hand mixer or whisk to keep it aerated and creamy. After the 3 hours, you are able to serve your ice cream and enjoy!You can add any of your favorite ice cream ingredients to this recipe such as sprinkles, chocolate syrup or fruit!

Procedure

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Recipe courtesy of “Homemade Vanilla Ice Cream” by Taste of Home (www.tasteofhome.com) & food science courtesy of “Ice, Cream… and Chemistry” by American Chemical Society (acs.org)

The Chemistry!

Why does ice cream stay smooth and creamy and how does it not freeze to a solid rock?Ice cream is made of these basic components: air (added by mixing your freezing ice cream every 30 minutes), sweeteners (sugar), fat (cream), and ice crystals (created by the freezing water particles in the mixture).Ice cream contains tiny little air pockets, added when mixing. Adding air helps delay the release of the flavor molecules, making the flavor last longer. Air takes up 30%-50% of the total volume. Sweeteners, aside from adding sweetness, help lower the freezing point of your mixture. This makes your mixture creamy instead of freezing to a solid rock!The fat added from the cream gives the rich and smooth texture. It improves the density, and increases the flavours. Ice crystals in ice cream are very small, making them easier to disperse through your mixture and allowing your ice cream to melt more slowly. Freezing your ice cream, melting it, and freezing it again can cause large crystals to form, making your ice cream grainy and causing it to melt faster.

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Flourless Peanut Butter Chocolate Chip Cookies!

Ingredients

1. 1 cup of peanut butter2. 1 cup of brown sugar3. 1 large egg4. 1 teaspoon baking soda5. ½ cup chocolate chips

Procedure

Preheat your oven to 350 degrees Fahrenheit. Combine peanut butter, brown sugar, egg and baking soda in a bowl. Mix well. Fold chocolate chips into mixture, ensuring not to overmix. Use your hands to create 1-inch balls of dough and place them on an ungreased cookie sheet. This recipe makes approximately twelve 1-inch balls. Make sure to space the dough balls out because they will spread quite a bit. Bake in oven for 7-8 minutes. Be sure not to overbake them! These cookies bake quickly!When you remove them from the oven, let them sit for 30 seconds to a minute, and then move your cookies to a cool plate. This prevents the cookies from overbaking once they are out of the oven. You can store your leftovers in an airtight container for a week!

Procedure

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Recipe courtesy of The Girl Who Ate Everything (www.the-girl-who-ate-everything.com) & food science courtesy of “The Science of Baking Cookies” (https://www.finecooking.com/)

The Chemistry!

Why do our cookies bake without any flour? Watch them from outside the oven as they cook. Why do they puff up? Let’s check out the science:

Flour causes cookies to be chewy, crisp or crumbly because flour absorbs moisture in the dough and affects the proteins (glutens) in cookies. Without it, we must rely on the science of our other ingredients!Cookies puff up because of baking soda! Baking soda mixes with the moisture and proteins from the eggs and peanut butter to cause a chemical reaction! Molecules get excited when mixed with baking soda and heated up. This causes them to expand, and steam is released! This is why cookies puff up!Why do cookies spread? Sugar melts when the temperature in the oven is high! This causes about half of the sugar in our recipe to melt and change states of matter, which allows cookies to spread out into circles!Actions such as mixing affect how your ingredients react as well! Overmixing can cause the molecules in ingredients to get stuck to one another in greater quantities, which can cause mixtures to become stiff. We don’t want that!