Peanut Brittle Chemistry Lab




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In my high school Chemistry class, we conducted an experiment called Foamed Saccharides with Protein Inclusions.  It left such a positive impression on me that mumblemumble years later, I still remember it.

This lab combined the best of food and science for me.  I tightened my precision in the chem lab and learned how to view recipes and cooking in a whole new light.  Who knew cooking involved chemistry, right? 

I was trying to research some other experiments that I could duplicate to revive the spirit of the Foamed Saccharides with Protein Inclusions lab.  And lo and behold, I found the original write-up from my very own chemistry teacher at Lapeer East High School!  What?!  This lab is from ages before the internet!  Yeah.  So I emailed Mr. Gormley, and he generously allowed me to use his lab write up exactly.  The words you will see here are his, and the obfuscation is intentional to encourage students to do their research!

Foamed Saccharides with Protein Inclusions

In this experiment you will produce a solid mixture composed mainly of various monosaccharides, disaccharides and polypeptide compounds. Since a great deal of heating is necessary to bring about the desired chemical and physical processes, care must be taken to avoid extensive thermal degradation (pyrolysis) of the product. Also cleanliness is necessary, since the product will be subjected to analysis by mastication. During the analysis you are to make observations regarding the production of the neural transmitter acetyl choline in the synaptic junctions.

Teaching Objective

By making peanut brittle, students will learn to determine percent yield of a chemical reaction and balance an equation.

  • saucepan with a capacity of one or two liters
  • 62 grams of a saturated monosaccharide solution containing D-glucopyranose and D-fructofuranose (about 1/4 cup)
  • 75 grams of the disaccharide a-D-glucopyranosyl-b-D-fructofuranoside (about 1/2 cup)
  • 20 mL of hydroxic acid
  • 20 grams of partially hydrogenated vegetable fat esters (about 1.5 tablespoons)
  • thermal insulating material
  • 50 to 60 grams of arachin, conarchin, oleic-linoleic glyceride protein pellets (about 1/4 to 1/3 cup)
  • 4 grams of sodium bicarbonate (about 1 teaspoon)
  • 5 mL of either 4-hydroxy 3-methoxy benzaldehyde or 4-hydroxy 3-ethoxy benzaldehyde (about 1 teaspoon)
  • thermometer (capable of reaching a temperature of at least 150 degrees Celsius)
  • 1000 square centimeters of aluminum foil
  • a large insulated manual stirring device

1. Mass out 62 grams of the saturated monosaccharide solution and place it into the saucepan along with 20 mL of hydroxic acid.

2. Into a clean 250 mL beaker, mass out 75 grams of a-D-glucopyranosyl-b-D-fructofuranoside (sucrose) and transfer it to the monosaccharide solution in the saucepan.

3. Heat the mixture slowly, stir constantly, and bring to a boil. Use as cool a flame as will maintain boiling. You must avoid thermal degradation of the saccharides.

4. Mass out 10 grams of partially hydrogenated vegetable fat esters and add to the saccharide mixture in the saucepan. Continue to heat and stir using some kind of thermal insulating material to prevent overheating your epidermis.

5. Mass out 50 grams of protein pellets and add to the saccharide mixture in the saucepan when the temperature of the mixture reaches 138 degrees Celsius (280F). Continue to stir and heat the mixture.

6. Mass out 4 grams of sodium bicarbonate and obtain 2 mL of 4-hydroxy 3-methoxy benzaldehyde or its substitute. Lightly lubricate a square piece of aluminum foil which measures about 30 centimeters on a side with partially hydrogenated vegetable fat esters. Note: You are only getting these substances ready to add they are not to be added until step 8!

7. When the temperature of the solution reaches 154 ¡C remove the saucepan from the heat and place near the piece of aluminum foil. Also, remove the thermometer at this time and check to make sure that the mercury bulb is still attached to the base of the thermometer. If the bulb is not attached THROW THE PRODUCT AWAY.

8. While one partner holds the sauce pan and is prepared to stir the mixture the other partner adds first the 4-hydroxy, 3-methoxy benzaldehyde and then adds the sodium bicarbonate. STIR VIGOROUSLY. When the mixture foams pour it on the aluminum foil and spread to a depth of O.5 cm.

9. When cool break up the product and subject it to analysis by mastication. Be sure to give some to your instructor so that he can analyze it and determine if the product meets the U.S.P. purity grade.

Questions and Problems

For further educational fun, follow up with these questions and problems:

1. Determine the percentage yield of product using the ocular method of approximation.

2. Comment on the amount of neural transmitter produced in the synaptic junctions during the mastication analysis.

3. In your opinion which of the following grades of purity are met by the product: Reagent, USP, or Tech.?

4. During step 8 of the procedure the mixture foamed due to the decomposition of sodium bicarbonate. Write the balanced equation of this reaction.

Final Notes and Thanks

Mr. Gormley says:

This is one of my "fun" experiments. I do it the last day before Christmas break. Students are responsible for supplying all materials except for the hydroxic acid (water). I generally assign this experiment one week before it will be done to give students a chance to locate the materials. They may need hints in locating some of the materials. You can have a lot of fun with this experiment when you give hints by not mentioning the name of the product.

Sarah says;

Thanks again Mr. Gormley, for introducing us to this fun experiment and breaking up the daily toil of high school .  Obviously this experiment had a great impact on me. Thanks also for allowing me to share your inspiration with the Instructables community! 

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    12 Discussions


    5 years ago on Introduction

    Hey, I did this in 8th grade!

    20+ years later, I still have the original lab worksheet (recipe) with stains and everything, and I've made it plenty of times.


    7 years ago on Introduction

    "Be sure to give some to your instructor so that he can analyze it and determine if the product meets the U.S.P. purity grade." :-)


    7 years ago on Introduction

    We must have gone to different high schools together, because my chem teacher did this exact same lab before Christmas.

    Students were given a choice between this experiment and one titled,
    "The Effects of Heat and Torsion on Saccharides"

    2 replies

    Reply 7 years ago on Introduction

    It is, indeed.
    Worked out rather well, too.
    Kinda freaked my parents out when I brought some home, said, "We made this in chemistry class today!", then popped a piece in my mouth and started chewing.


    7 years ago on Introduction

    Cool! We did the same thing in high school except they called it crystalline structure with protein pellets. I like your name better. :)


    Reply 7 years ago on Introduction

    I recall some prank he talked about that involved making one of those snake fireworks like you set off on 4th of July. Only giant-sized. And in the teacher's bathroom. I'll let you imagine the rest.