Wednesday January 12, 2011: Pre-Class Homework
Coffee Questions:
1. In what places was coffee first discovered and then cultivated? What are some of the legends of the origins of its roasting and brewing?
a. Source used: http://hubpages.com/hub/The-history-of-Coffee
b. Most people think that coffee was first cultivated in Ethiopia. However, the Republic of Yemen is really the place where coffee was first discovered. The Legend of Dancing Goats tells the story of how coffee was discovered. The story says that a young goat herder came out to the fields to find his goats missing. He later found them out in grazing lands eating red fruit. The goats were acting excited, crazy, and strange, but he was hungry so he joined them in eating the fruit. They all began to act strangely, as the fruit had a stimulating effect on them. A mystic saint then came along and figured out that the strange behavior was a result of the plant so he decided to cook the seeds and tasted the bitter liquid. However, it had a pleasant aroma when roasted, which came to be known as coffee! Other legends say that coffee originated in the Kingdom of Kaffa in Ethiopia. The beans that originated from Kaffa, came to be known as Kaffe and then Coffee. However, it is a widely accepted notion that coffee had its origins in Yemen.
2. Petracco tells us that the end products in coffee roasting are typically on the order of 10,000 Daltons (which is the same as saying “10,000 grams/mole”). Approximately how many atoms is that?
a. The answer is 1.66 x 10^-20 atoms
3. Petracca states on p. 1166 that espresso is “often considered a „strong‟ cup of coffee” and “fully deserves this attribute based on its sensory properties.” However, it generally contains a much smaller amount of caffeine than we might anticipate. Why is this (in terms of the chemistry of brewing)?
a. This is because of the small size of the serving of espresso that is usually served. Usually only 6.5g of roasted coffee are used to make a serving of espresso. Also, the coffee bean has a shorter contact time with water that is allowed during extraction. So, the caffeine dissolution is thus slow and almost a quarter of the caffeine remains with the spent grounds.
4. In order for you to use olfaction to taste coffee, volatile molecules must make their way up inside your nose. Choose one or two molecules from the food-info page. Can you explain, in chemical terms, why these molecules are volatile, compared to water or a fatty acid (e.g., CH3(CH2)16COOH)?
a. Guaiacol
b. This molecule is volatile because it contains a phenyl ring with alternating double bonds. This would be more volatile than water or fatty acids because these alternating double bonds mean that there are going to be many free moving electrons. These free moving electrons are going to cause the molecules to vaporize and thus easily give off an aroma.
5. One of the reasons for the success of coffee shops such as Starbucks is that they throw away beans that were roasted more than a week ago. Why are freshly roasted coffee beans better than months-old coffee (provide a chemical explanation)?
a. Website used: http://en.wikipedia.org/wiki/Coffee_roasting
b. Freshly roasted coffee beans are better because they give off the flavor that raw coffee beans do not. The process of roasting coffee transforms the physical and chemical properties of the raw coffee beans into the kind used in coffee. This roasting is what actually gives coffee its distinct flavor. Raw coffee beans contain all the acids, proteins, caffeine etc but do not have a taste. The heat in roasting speeds up the Maillard chemical reactions and thus enhances the flavor. However, after coffee is roasted it is not as stable as before so it must be consumed soon after the roasting period.
6. Count the carbons in cafestol. If it is a “diterpene,” how many carbons are found in a terpene?
a. Diterpene= 20 carbons/2= 10 carbons in a terpene.
Tea Questions
1. Trace the history of tea from the far-east to the west. When was tea first discovered and how was it introduced to the west?
a. Tea is a native of East and South Asia and originated near India, north Burma, southwest China, and Tibet. However, there is no exact locale of tea’s precise origin. Tea has been recorded for early usage in China by the Qin and Tang Dynasties. After China it spread to Korea and Japan. In the 19th century, tea spread to the Western nations via trade with China. It has since spread to innumerable countries around the world.
2. How was tea initially used during the Han Dynasty (206 BC – 220 AD)?
a. Tea greatly grew in popularity during the Han Dynasty. Right after this time, tea became the national drink of China. During this dynasty, it became common practice to send the finest of teas to the emperor’s court as a tribute to him. Tea was also manufactured in brick form from which powdered tea would be derived. During this time, tea popularity also spread to Japan where the Sung method of tea preparation took hold.
3. Which western traders are credited for bringing tea to the west?
a. The East India trading company was rather influential in bringing tea to the west. However, there was corruption within this tea distribution monopoly. In 1907 an American tea merchant, Thomas Sullivan began to distribute samplings of tea bags. However, the 19th century was really when western traders of tea began to enter the scene.
4. What was the Boston Tea Party about?
a. This was when enraged Americans dumped numerous crates of tea into the Boston Harbor to oppose the steep tea tax Britain was putting on tea. Great Britian was asking for a tax of 3d per pound which was outrageous to Americans. The Boston Tea Party happened not only as a retaliation, but also to show their desire for independence from their mother country.
5. What addiction did the English create among the Chinese people due to their desperate dependency on Chinese tea?
a. Due to the desperate dependency on Chinese tea, smuggling and illegal trading of tea became widespread.
6. Which chemical in tea has psycho active properties known to reduce mental and physical stress?
a. Tea polyphenols
7. What other chemicals are found in tea and what are their therapeutical benefits?
a. Flavanoids, amino acids, antioxidants, vitamins (c,E, and K) and polysaccharides.
8. How is green tea produced?
a. The withered leaf is steamed and rolled before drying or firing. When it is brewed, the green tea has a pale color and the wet leaf is left whole. It is mostly drunk in China, Japan, and parts of South America. It is usually a specialty tea in the U.S.
9. How is black tea produced?
a. The leaf is spread on large tea racks and left to wither. The moisture evaporates and the warm air leaves the leaf rather flaccid. The process often takes 10-16 hours. The leaf is then broken by machine so that all enzymes and juices are released. An Orthodox machine rolls the leaf into particles. The leaf is then chopped and laid on trays to cool. After this is complete the leaf is dried or fired. After this it is put into chests and sorted by size. Then the factors tea tasters will test the tea to make sure no mistakes have been made.
10. Read the Key Tasting Terms described in Tea Tasting Notes (page 1), and describe using the key tasting terms, how you prefer your cup of tea.
a. I like green and white teas the best. I like tea that has a little bit of sweetness with just a light tannin taste. I like it when the length of the tea taste lingers just a little bit longer than the taste. I also like tea that has a light body to it, so it is not too heavy. All the parts must be in balance to give the right array of tastes on the tongue.
11. Based on your moods, write down the types of teas you may wish to consume. (refer to the Tea Tasting Notes for tea and mood information)
a. Keemun, Darjeeling, Early Grey, and Chai.
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