Introduction

We all know and love the taste of that quintessential treat, that wonderful concoction that makes our mouths water--candy. It comes in so many forms to tempt the tastebuds that today, indeed, the possibilities with candy are endless. But how often do we stop and ponder the amazing properties of a lollipop or wonder and the brilliant color in a Lifesaver? How often do we realize the science and artistic talent that go into creating these treats which we take for granted? In my project, I have sought to shed light on candy from both a scientific and an artistic standpoint, by focusing on basic hard candy as an edible Glasslike material and by testing the absorption of dye into the sugary substance at different temperatures.

Background

Granted, when someone mentions "art-forms", candy-making and confections is probably not the first thing to come to mind. But, after a bit of study and observation, it becomes quite clear just how artistic the sweet stuff can be. The basic principles of candy-making are based in chemistry: it has everything to do with timing, the correct proportion of ingredients, and reactions between those ingredients. In this way, it is also a form of science. In my project, I chose to test the absorption of dye into basic hard candy at different temperatures in the cooking process to see if there would be any variation in the color of the final product. The initial idea for this project was inspired by my realization of how closely related candy is to another everyday substance--glass. Both candy and glass are formed by heating fine, grainy particles at high temperatures, and are made beautiful through quick shaping and handling. Dr. Bordley explained to me that glass is essentially a liquid at a cool sold-like state, as is hard candy. The same methods used for glass blowing can also be applied to the sculpting of sugar--heat, quick and delicate movements, and the occasional application of color and flame. Through my project, I hope to give more validity to candy-making and confections as an independent art form worthy of consideration by designing a scientific experiment based on everyone's favorite treat.

Procedure

Materials

5 pound bag of sugar (yield approx. 12 cups)

2 jars Karo light corn syrup

water

1 bottle yellow food coloring

1 bottle lemon extract (optional)

two eyedroppers (for food coloring and extract)

cooking spray

heavy saucepan

high-temperature hot plate

standard candy thermometer (if none available, a lab thermometer will also work)

airtight containers

heat-resistant candy molds, or any similar object (I used two pecan tassie pans--about the size of a mini-muffin pan)

measuring cup

colorimeter

Candy Preparation Procedure

I. First, I gathered all of my materials together to facilitate a smooth procedure. For scientific purposes, I also set up a table of Fahrenheit and Celsius degrees for reference:

I also chose four different temperatures at which to add the food coloring:

II. Before beginning the formal procedure, I performed a trial run of the candy recipe to avoid speed bumps during the actual process. For this trial batch, I added the two drops of food coloring at 300°. Thankfully, I encountered no problems during the trial run; I kept the resulting candies in airtight containers as back-up.

III. After organizing my materials and setting up the above parameters, I began my actual procedure, starting with batch #1, room temperature. First, I measured 2 cups sugar, 1 cup water, and 2/3 cup light corn syrup into the saucepan and stirred slightly to combine the ingredients. Using a small eyedropper, I added 2 drops of yellow food coloring at room temperature to the mixture, and stirred once more to distribute the dye evenly. I then placed the saucepan on the hot plate, and turned the setting to high, noting the time at which this heating process began. I monitored the progress of the mixture by occasionally checking the temperature on the candy thermometer and by stirring every several minutes. Once the mixture had been boiling for several minutes and reached a temperature of 300° F, I removed the saucepan from the hot plate and added a few drops of lemon extract. After adding the flavoring, I refrained from stirring while the boiling and bubbling subsided. As soon as all bubbling had stopped, I quickly spooned the mixture into lightly greased candy molds (mini-muffin pans) filling each mold about half full. When working with the candy, it is important to work quickly and carefully, because once removed from the heat, the substance begins to solidify rapidly, yet remains extremely hot to the touch. As soon as I had filled the molds, I placed the pan in hot water to melt and remove any excess candy or residue.

IV. I repeated the same process for batches #2, #3, and #4, varying only the temperature at which I added the two drops of yellow food coloring. With batches #2, #3, and #4, it became imperative that I monitor the temperature of the candy closely so that as soon as the thermometer read the 150, 220, and 300 degrees F (respectively) I could add the two drops of dye. After batches #1 and #2, there was already a visible darkening of color present in the results. However, when batch #3 (220° F) was completed, the resulting candy was considerably lighter than batch #1 (room temperature). Because of this discrepancy, I used the time set aside for batch #4 (300°F) to repeat batch #3. Since I had conducted a trial batch of candy with food coloring added at 300°, I was able to use the trial candies for batch #4. (See Data and Observations for more discussion of this)

For each batch, once the candies had completely cooled and solidified, I began to extricate them from the molds. Although I had greased the molds with cooking spray, they were still stubbornly difficult to remove. With Dr. Kirven's help, I discovered that the easiest way to accomplish this was to invert the mold pan, cover its back with a piece of wood and pound it with a hammer. Although noisy, this did the trick. Once the finished candies had been freed, I stored them in airtight Tupperware containers with labels on a shelf in the lab where they would remain cool and dry.

Colorimeter Procedure

I. Once I had completed each of the four batches of candy, I began to take sets of colorimeter readings to compare the saturation, lightness, and hue of each batch. For each batch, I chose three random samples of finished candy to take readings from. With each of these three samples, I took L*a*b and Munsell values for both the front and back of the piece. Once I had obtained readings for each of the three samples, I averaged their results to form an average colorimeter reading for the batch of candy from which they came. Therefore, after taking the first set of readings, I had an average colorimeter reading for batch #1, #2, #3, and #4.

I repeated this process a second time, producing a second average colorimeter reading for batch #1, #2, #3, and #4. With two averages in hand for each batch, I proceeded to average these two sets of readings to produce one overall, comprehensive L*a*b and Munsell reading for each of the four batches. (For two preliminary and final, overall average of each batch, please refer to Data and Observations)

II. After comparing colorimeter results, I drew conclusions about the experiment and distributed the candy to members of the Chemistry and Art class.

Observations and Data

Observations During Candy-Making

Figure III: Finished candy product (clockwise from top: 150 degrees, 220 degrees, 300 degrees, and room temperature)

Observations of Final Candies

To obtain the most accurate representation of each entire batch of candy, I took two separate sets of readings for each of the four batches. For each batch, I chose three samples from which to take L*a*b and Munsell readings, averaging the results to produce 1 set of readings for the entire batch. I performed this process twice for each batch of candy, making sure to select three different samples for the second set of readings. Results are listed in the table below.

Preliminary Average Colorimeter Readings

For each batch, these two sets of average readings were then themselves averaged to produce final, overall readings for the candy. Results listed in table below.

Overall Average Colorimeter Readings

Conclusions

Discussion of Colorimeter Readings

Looking at the final, overall averages of L*a*b and Munsell readings for the four batches of candy, we can find quantitative evidence to back up what I found in the experiment: that the higher the temperature at which food coloring is added to a cooking batch of hard candy, the darker the hue will be. Disregarding Batch #3 (the anomaly) for a moment and considering batches #1, #2, and #3, we can see that in the Munsell readings, the color value is decreasingly yellow, beginning at 6.0 Y for batch #1 and ending at 6.4 YR for batch #4. Note that batch #4 is not simply 'Y', but rather 'YR', suggesting that more red is detected in the 300 degree samples, thus producing a candy more orange in color. In the L*a*b readings, the lightness from batch #1 to batch #2 increases, meaning the color is becoming darker, and in batch #4, the lightness reflects that of a dark orange. Also, the "a" readings for batches 1, 2, and 3 are all negative, suggesting some sort of presence of green, and their high positive "b" readings indicate a good deal of yellow. Note that in batch #4, the "a" reading becomes positive, indicating a stronger presence of red, thus influencing the candy's orange hue.

Overall Conclusions

From this experiment, I have been able to conclude that, on the most part, the color of hard candy becomes darker as the temperature at which dye is added increases. Although I am not sure exactly why this occurs, I do have a few theories. The main ingredient in hard candy is sugar, or glucose, whose formula contains 6 Carbon atoms, 12 Hydrogen atoms, and 6 Oxygen atoms. The two primary ingredients in food coloring are propylene glycol (3 Carbons, 8 Hydrogens, and 2 Oxygens) and propylparaben (10 Carbons, 12 Hydrogens, and 3 Oxygens). Recall that glucose can exist in three different formations including a ring and a straight line. My theory is that, as the temperature increases, the sugar is more likely to change the arrangements of its atoms, making it easier for the food coloring to bond with the sugar. Also, since the two main ingredients in food coloring contain the same elements as sugar, and since like dissolves like, perhaps higher temperatures facilitate interaction between the two. Also, Dr. Bordley suggested that perhaps the darkening in color could be attributed to the simple browning of the sugar as it is heated. As for the reproducible anomaly of batch #3, I unfortunately have only one possible explanation. While making the candy, I noted that each batch began boiling at approximately 220° F, which is also the temperature at which I added the food coloring for batch #3. Perhaps the state of the ingredients at the moment boiling begins is such that the dye is not absorbed as the other batches were. This would be an interesting experiment to perform in the future--possibly with other colors as well. Overall, I have gained a greater respect for those persons who work with confections; it is a true art form that calls for great patience and curiosity to test and vary certain properties.

Other References

Block, Toby F, Wade A. Freeman, and David W. Oxtoby. Chemistry: Science of Change, 4th edition. Pacific Grove: Brooks/ Cole, div. Thomson Learning Inc, 2003.

Wonderful information on the history of glass can be found at:

http://aic.stanford.edu/

Hard candy recipe from the Food Network website:

http://www.foodtv.com

Acknowledgements

This project would not have been possible without the wonderful help of several people--I truly appreciate everyone's support!

Special thanks to Dr. Bordley for allowing me to run with this idea and for helpful suggestions in Lab. Thanks to Dr. Kirven for the Band-Aids and for finding an easier way to free the candy from the molds. Thanks to Miss Stephanie Owens for the fantastic explanations of chemistry principles that I couldn't grasp and for the use of her Chemistry text book. Thanks to Miss Alison Reynolds for always being patient with me in Lab and for keeping me company all those afternoons when we two slowpokes were the only ones left. And thanks to the entire Chemistry and Art 2004 class for making this such a memorable semester!