CHEM 306-02

For last week’s class, we went on a field trip to Claflin Bakery and learned about the science of baking. We baked red velvet cupcakes with different variables applied for the amounts of baking soda. Among many topics that Lori discussed, I found the history of red velvet cupcakes interesting. I always thought of red velvet cupcakes as a gimmick with only its color modified from chocolate cake. Of course, the red color of the cake wasn’t originally from the dye. So, I decided to look into the source of redness that gave red velvet cupcakes its name.

The acidity of buttermilk and vinegar reacts with basic baking soda to fluff up the cake with CO2 air bubbles, giving it a nice and smooth velvety texture. In this process, the vinegar and buttermilk also reacted with cocoa that traditionally contain anthocyanins, which are antioxidants also found in red cabbages, pomegranate, and many other species. Anthocyanins react with both acid and base and give distinct color changes according to the different amounts of [H+]. When they react with acid, they turn red, and they react with base, they turn more brown. So, it was possible to get the red color just by adding vinegar and buttermilk with cocoa and flour, and it’s still possible to avoid using food coloring if we can get pure cocoa. However, today, most cocoa powder is processed with alkalizing agent, a base. So, traditional coca has a pH ~5 and base-processed cocoa powder has a pH ~7-8. Therefore, with the shifted pH range of color change in processed cocoa powder, it is hard to get the bright red color, making the food dye necessary.

I think that this science behind red velvet cupcake’s color is related to our results from the chemical leavener experiment. For the cake with no baking soda, we saw that it had a bright, highlight red color when we had put in equal drops of food coloring dye. This was probably because the acids (vinegar and buttermilk) that should act with the base (baking soda) to act as a leavener and create air bubbles in the normal recipe does not have the basic compounds to react with in the no BS sample. Instead, the acid reacts mostly with the cocoa powder to reach the pH for color change in the processed cocoa powder, and give a more red color than other samples. So, at the cost of having a dense and uncooked interior of the cake, we were able to get a bright and pretty color on the outside.

Last week we explored the nature of chocolate, food of the gods. I learned from our Harold McGee text, “On Food and Cooking”, that the first cacao substance was actually a sipping liquid in Central and South America where the nectar was flavored with a number of ingredients vanilla, chili, wild honey, and achiote. In the 17th century, Europeans began experimenting with solid forms of the cacao bean…and hence the birth of the confectionary we know and love today.

We learned that there are six different fat crystals, only two of which are in a stable condition. A highly meticulous process of tempering allows the stable crystal types to gather most of the fat molecules to themselves before the unstable crystals begin to form. These preferred crystals will predominate in melted chocolate if the confectioner carefully maintains the temperatures above the melting point of unstable crystals but below the melting point of stable crystals. This tempering range is 88-90 degrees Fahrenheit for dark chocolate. One can carefully melt the chocolate and slowly bring it down to this range or “seed” the liquid with solids already in the ideal structure.

High quality chocolate is glossy, dry, and hard, featuring a beautiful crisp snap when broken. When chocolate is cooled in an uncontrolled way, the fat molecules form loosely packed, unstable crystals and the chocolate is soft and greasy.

Therefore, crystalline structural arrangements are critical in determining the quality of the chocolate. Consider this the next time you eat a chocolate bar that re-solidified after melting…you may want to temper it on a double-burner before sticking that now inferior chocolate in your mouth.

Indulge…temper that chocolate.

Sarah and I are working on running an egg white on a gel for our Project 2. We are learning about which mixture of proteins are in an egg white, mimicking this mixture via stock proteins, and running it alongside a real egg white. Last Friday we ran the egg white “quick and dirty”– i.e., we only strained the egg white through cheese cloth and added loading buffer.

Not a huge surprise– it didn’t show up that well. Now we’re working on finding a way to extract soluble proteins from the egg. Hopefully we can extract these proteins from our egg whites and get a successful run. From there, we will compare the protein composition of cage-free organic eggs versus conventionally raised eggs.

Hi everyone!

As we prepare for our visit to the Claflin bakery tomorrow, I thought it could be fun and useful to start thinking about CO2 bubbles in baking. We try to produce CO2 bubbles in a couple ways in baking– mostly through chemical leaveners (i.e. baking soda, baking powder) or through yeast.

Elle and I worked a lot on how chemical leaveners work in order to solve our problem in Project 1. Stay tuned– we’ll tell you more about it in our in-class presentation in a few weeks. Until then, here’s an interesting visual representation of how altering quantities and ratios of baking soda to acid can affect the CO2 bubble size and distribution.

You can see in the photo that the “1 tbsp BS” cupcake (all the way on the right) has a more even distribution of bubbles compared to the big air pockets in the other two. (especially the original)

*technical difficulties uploading photo, hopefully to be fixed soon.

Annie and I have been working on our “Solving a Chef’s Kitchen Dilemma” project with Lori Davidson from the Claflin Bakery on campus. We have been investigating the effects of chemical leaveners on the crumb structure and overall texture and taste of the bakery’s famous red velvet cupcakes. We are researching acid-base reactions and the correct balance and neutralization of the acidic components of the recipe, mainly vinegar (acetic acid), and the basic components, baking soda (sodium bicarbonate). Lori’s original recipe, we found, did not have enough base (1/4 teaspoon baking soda) to counteract the amount of acid present (1 tsp vinegar).  We conducted 3 trials last week and the results were quickly visible. Check out our photos in our google drive folder!

http://www.npr.org/blogs/thesalt/2014/11/19/365213805/just-what-is-in-pumpkin-spice-flavor-hint-not-pumpkin?utm_source=facebook.com&utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_content=2044

My friend sent me this link today and I thought I would share it. This NPR clip talks about the food scientists that have developed the artificial/natural flavor components of “pumpkin spice”, used most commonly in pumpkin spice lattes. Interestingly enough, there is no actual pumpkin in “pumpkin spice”. The pumpkin spice flavor comes from cinnamic aldehyde (cinnamon), eugenol (allspice or cloves), terpenes (nutmeg), and vanillin (vanilla). Not all pumpkin spice flavors are the same. Based on the tastes and preferences of consumers in different parts of the country, flavor scientists create variations of different pumpkin spice flavor formulas. The pumpkin top notes come from nearly 340 character impact compounds. I learned that scientists do not actually have to use all 340 compounds when developing a product. The human brain can come up with the pumpkin spice flavor with just 5 to 10% of these flavor components. Flavor chemists are important for large-scale food companies because by replacing “real” ingredients for chemical substitutes, they can produce a consistent product for a fraction of the cost.

Jocelyn, Sarah, and I went to visit Juniper last Thursday to watch Tim make the mint oil in person. It was really awesome being able to go into the kitchen area to watch where the magic happens.

First of all, Sarah and I got to help Tim out by picking out the leaves he made the oil with. After collected our 2 cups of mint leaves, Tim quickly blanched the leaves in boiling filtered water for 3 seconds. He immediately transferred the mint leaves into an ice bath, leaving them in there until they were cool. He gave the mint leaves a gentle squeeze to remove the excess water and then blended the cool mint leaves in a blender along with the olive oil.

The mint oil turned out to be a nice neon color! However, when he brought out a bottle of mint oil that he had made 5 days previously, there was an obvious difference in the color. the 5 day old olive oil had a brown and dark yellow tinge to it.

There are several things that we are thinking that we could test.

1) Ion replacement: The loss of the Mg+ ion due to heat perhaps could be replaced with Zn? I’m not sure how feasible this option is.

2) Changing the pH: increasing the pH will prevent the H+ from taking the place of the Mg2+ in the chlorophyll.

Could we perhaps do a mixture of both? There are a lot of questions that need to be answered and we need to do more research on it.

This week, Annie and I had an opportunity to work with one of Professor Didem’s research assistants, Stephanie, to learn Gel Electrophoresis in great detail. This learning process was in preparation for Project 2, where we are trying to identify whether or not there is a difference in protein content between normal eggs and eggs with supplements fed. Gel Electrophoresis, not only with DNA but also with proteins, is a very useful skill that always come in handy for biologists and chemists! So here is my step by step guidance to it:

There were many more steps in preparing for gel electrophoresis than the actual running process. First, we have to create our samples and the loading buffer. For gel electrophoresis, loading buffer usually contains some SDS (a form of detergent that puts on a lot of negative charges onto the sample molecules so that we get the mass-to-charge ratios with the charges of different components being constant and only masses differ), glycerol to weigh down when loaded onto gel, and Tris buffer to maintain the pH. Second, we must our samples by setting the hot plate (with some water so that our plastic micro tubes don’t melt) temperature to 100 celsius and putting our samples in once it reaches the temperature.

While the samples are heating up, we get the pre-made gel (most common ones are agarose gel and polyacrylamide gel; we’re using polyacrylamide gel) that has been refrigerated and insert it onto one side of the box and put in glass on the other side. We must also get a rubber tube on the edges of the box so that the gel gets nicely sealed onto the box.

Then, we pour some running buffer (we’re using 1* Tris-Gly buffer)  into the space that holds the gel/glass, as well as into the large space in the box up to the point indicated in the diagram.

Before taking out the comb from the gel, we may use a “cheat sheet” to see the initial positions of the hole more easily. And pour in a little more running buffer so that it fills to the top inside the wells.

After this is all setup, we take the heated sample and pipette out some amount (20 micro liters in ours) and load our samples onto the gel.

We also had a chance to use a sonicator, which is an apparatus for separation of materials using ultrasound. We’re going to use this apparatus to homogenize our egg sample. When we were using this, we had to wear headphones to block some of the piercing ultrasound and we could adjust the frequency and magnitude of the ultrasound shocks. It was pretty cool to see that sound waves could be used in conjunction or replace our use of centrifuge. Annie and I are excited to use all these new skills in the upcoming weeks!

This week we made an excursion to Cambridge to attend the Harvard Food Science Lecture presented by Christina Tosi of Milkbar in New York City. The topic of the lecture, Emulsions and Foams, was a perfect follow up to our last class when we made mayonnaise and meringue. Christina first demo-ed her famous cornflake marshmallow cookies. She explained the secret to her cookies was a 10 minute creaming process in which she beat sugar and cold butter in a stand mixer. Only after 2 to 3 minutes did she add an egg to the mixture. In just these two steps, we could already see the creation of foams and emulsions. By beating the butter and sugar together, millions of air bubbles were also becoming incorporated and the mixture became fluffy and lighter in color. The egg (specifically the egg yoke) helps form an emulsion between the sugar and butter. Christina also talked briefly about the leavening agents baking powder and baking soda. Baking soda, sodium bicarbonate, requires interaction with an acidic component in the recipe. Baking powder consists of baking soda and an acid. The baking powder she used in her recipe was double acting. The first rise occurred when the baking powder came into contact with the moisture from the batter and the second rise occurred with its interaction with heat from the oven. This was also helpful information for Annie and I as we are exploring rising agents for our “Solving a Chef’s Problem” project.

The class made an excursion to Cambridge this week to sit in on the Harvard Food Science lecture featuring Milkbar’s Christina Tosi and her use of emulsions in her famed, saliva-inducing, all-American desserts. Although there was a bit less of the chemistry lecture component from the Harvard professors, Tosi appeared to know quite a bit about the chemistry behind her culinary decisions. She demonstrated the process of making her marshmallow cookies and chocolate-coffee-passionfruit cake.

It was so insightful to hear the scientific reasonings for certain baking rules I have learned to adhere to after being active in the kitchen for seven years but did not know why they work. For example, I recognized that more creaming of butter and sugar equated to fluffier cookies. Also, over-handling of the dough once flour is added would make rubbery cookies. Chef Tosi explained that beating the butter and sugar incorporates air creating bubbles that contribute to a flaky, light cake. The mixture turns whiter as it is creamed because as more bubbles are created, light is scattered. She also explained that more aggressive handling of flour results in greater formation of the strong sticky protein called gluten, great for full-bodied breads but undesirable in cookie and European cake recipes. At the end of the lecture, I was able to get my fan-girl picture with Christina Tosi!

After enduring the delectable fragrance of freshly baked goods during the lecture, a trip to Flour Bakery was necessary. From one successful female chef to another. Each student ordered a sandwich, prepared on Joanne Chang’s special bread. As I sunk my teeth into the plush, moist bread that I often dream about, I thought of the high-protein flour that had likely been used. My next personal kitchen endeavor will be mastering the art of bread making. Professor Didem ordered a layered hazelnut cake that was divine.

The entire day was a beautiful testimony to the benefits of being part of an intimate community; a group of Wellesley students can audit a Harvard course and a professor will spend time with her students, altruistically open her heart and share life wisdom over some treats. At times like this I wonder if these opportunities in my life are real.