Our week started off rather excitingly with our Edible Science Fair, in which the class split into 4 groups and each presented on a topic of their choice, having to do with the chemistry of food, of course! The four groups that had stations at the fair presented on Enzymes, Emulsions, Fermentation and Coagulation. Each group was responsible for having visuals to help participants learn about their respective chemical properties and also each group had food dishes that adequately displayed their chemical property in food.
To start off, Team Enzyme had many different food dishes that were used to explain how much of a role enzymes play in our food. First, they made two batches of the same recipe of beef stew, with one difference, one batch had meat that had been tenderized and the other batch had meat that was not tenderized. Meat tenderizer can be bought at any local grocery store and the active ingredient in meat tenderizers is an enzyme called bromelain. In practice, the tenderizer should make the meat much easier to chew, the meat should “melt in your mouth”. These two dishes proved to illustrate this property very well as one could definitely taste a difference in the meats of the two respective stews. Team Enzyme also had various types of Gouda cheese that could be sampled to illustrate the effects of the enzyme renin on the protein casein. Renin is the enzyme in cheese that breaks down casein, which is the primary protein structure in cheese. This breakdown of proteins into amino acids allows for flavor development in more ripe cheeses. The group had out three different types of aged Gouda to illustrate the flavor and structural changes over time. Finally, the enzyme group displayed different types of food that undergo browning due to oxidation from the air. Polyphenol oxidase is the enzyme that is responsible for this oxidation. This phenomenon can be seen in apples and avocados when they are left out in the open for extended periods of time. To illustrate this phenomenon, the group cut apples at various times before the event and let them sit out to show the effects that browning had on the fruits.
Next comes Team Emulsions, who demonstrated their property through homemade whipped cream and salad dressing. An emulsion is a mixture in which oil is dispersed in water, something that should not normally happen. This can happen because of the properties of an emulsifying agent, such as lecithin, that has a two different ends. One end is hydrophobic and attaches to water and the other end attaches to the oil. Salad dressing is a classic example of an emulsion as it is fat that is suspended in water. Whipped cream is an example of an emulsion in which air is suspended in liquid, and the fat in the cream acts as the emulsifying agent.
Third was Team Fermentation and they demonstrated the property of fermentation using apple juice and yeast. Fermentation is a process in which sugar is converted to gas or alcohol. The classic example of fermentation is its use in the process of making beer and other alcoholic beverages. To demonstrate their topic, this group fermented apple juice, in turn making it an alcoholic cider. The group added yeast and sugar to a gallon of apple juice and allowed it sit uncovered in a dark room for a few days. They also had a gallon of regular apple juice so that participants could taste the difference between the two. Finally, to demonstrate the byproducts of fermentation the group added yeast, sugar and water to a few beakers and placed balloons on the openings of the beakers. Because CO2 is a byproduct of fermentation, the balloons started to full with air as the process went along.
Vernon, Adonis, and Zhou presented a terrifically engaging and informative presentation about coagulation in foods. They exhibited the different modes of coagulation, for example via pH changes in the formation of cottage cheese, enzymes in the formation of regular cheese, and salt in the formation of tofu. They used photos, such as the one below, in a slideshow to inform fair-goers of the implementation of coagulation in the production of cheese and other products. Zhou made a delicious traditional Chinese tofu dish with plenty of samples available so that people could taste the product of coagulation! The team members would then explain the coagulation of the conglycinin protein in soybeans by magnesium ions in magnesium sulfate in the production of tofu. The magnesium ions bind to the negatively charged parts of the protein, causing them to coagulate. The team also made eggs and showcased their coagulation process.
All in all, it was a very successful event and we felt that we helped people to understand some chemical aspects of the foods that they see on a regular basis. We also learned a lot in the process!
During class this week, we had the wonderful opportunity of visiting Cornell’s New York State Agricultural Experiment Station (NYSAES). For those of us that are interested in possibly pursuing a career in food science, this was like a fairytale; even better than Disneyland for a child. While, they were in the process of moving to the Cornell facility, the Food Science department at NYSAES was eye-opening. We learned real-world applications of chemistry, including physical chemistry, in the food industry. For example, the contraption pictured below is used for distilling, and is made of copper because copper helps remove sulfides from the distillate product.
One of the most intriguing parts of the visit was the lab. Dr. Gavin Sacks led us on a tour of the facility, and then finally to the highly anticipated olfactometer. The olfactometer is a specialized machine that is built to receive a vial of fluid and then transmits the various odorous compounds of the substance out of a tube that is placed at the edge of a participant’s nose. I had the blessed opportunity of experiencing the olfactometer containing a vial of freshly brewed coffee. Below is the setup of the olfactometer. Once the coffee sample was placed in the appropriate receptacle, the coffee option was selected in the software on the computer. A list of smells then came up on the screen. After waiting a few minutes for the compounds to be recognized by the machine, I started to smell things. The software ran a background timer, and various smells were expected to appear at different times, based on the fact that the sample was coffee.
The experience was incredible. Olfaction is a sense we usually take for granted, and most people do not understand how many different compounds are involved in different smells. There are thousands of compounds that make up the smell of freshly roasted coffee, but intriguingly the lab has found that every different smell can be recreated using only a few hundred chemical compounds; for example, it only takes about 24 to make a very good approximation of bourbon. When I sat at the olfactometer, I got to experience the isolated compounds that contribute to the delicious aroma of a fresh cup of coffee. However, not all of these compounds smelled as delicious as coffee. For example, one of the smells to be identified was the smell of dirty socks. This aroma came up quite a few times, and is a characteristic smell of short chain carboxylic acids. Our experience at the NYSAES showed us just how much thought and effort is involved in the production of food, and the complexity of the makeup of food.