Name: Teacher: Date: Class/Period:
5 10 15 20 25 This passage is adapted from the book Napoleon s Buttons: 17 Molecules That Changed History by Penny Le Couteur and Jay Burreson ( 2003 by Micron Geological Ltd. and Jay Burreson). Pepper, from the tropical vine Piper nigrum, originating in India, is still the most commonly used of all spices. Today its major producers are the equatorial regions of India, Brazil, Indonesia, and Malaysia. The vine is a strong, woody climber that can grow up to twenty feet or more. The plants begin to bear a red globular fruit within two to five years and under the right conditions continue to produce for forty years. One vine can produce ten kilograms of the spice each season. About three-quarters of all pepper is sold as black pepper, produced by a fungal fermentation of unripe pepper berries. White pepper, obtained from the dried ripe fruit after removal of the berry skin and pulp, makes up most of the remainder. A very small percentage of pepper is sold as green pepper; the green berries, harvested just as they are beginning to ripen, are pickled in brine. Other colors of peppercorn, such as are sometimes found in specialty stores, are artificially dyed or are really other types of berries. 45 50 55 60 65 70 signal along the nerve to the brain, saying something like Ow, that s hot. Unlike the single species of peppercorn, chili peppers grow on a number of species of the Capsicum genus. Native to tropical America and probably originating in Mexico, they have been used by humans for at least nine thousand years. Within any one species of chili pepper, there is tremendous variation. Capsicum annuum, for example, is an annual that includes bell peppers, sweet peppers, pimentos, banana peppers, paprika, cayenne peppers, and many others. Chili peppers come in many colors, sizes, and shapes, but in all of them the chemical compound responsible for their pungent flavor and often intense heat is capsaicin, with the chemical formula C 18 H 27 O 3 N and a structure that has similarities to that of piperine. Both structures have a nitrogen atom (N) next to a carbon atom (C) doubly bonded to oxygen (O), and both have a single aromatic ring with a chain of carbon atoms. That both molecules are hot is perhaps not surprising if the hot sensation results from the shape of the molecules. 30 35 40 The active ingredient of both black and white pepper is piperine, a compound with the chemical formula C 17 H 19 O 3 N. The hot sensation we experience when ingesting piperine is not really a taste but a response by our pain nerves to a chemical stimulus. How this works is not fully known, but it is thought to be due to the shape of the piperine molecule, which is able to fit onto a protein on the pain nerve endings in our mouths and other parts of the body. This causes the protein to change shape and sends a 75 80 The heat we feel from peppercorns appears to be directly proportional to the amount of pepper in the food. Heat from a chili pepper, on the other hand, can be deceptive. Color, size, and region of origin all affect the hotness of a chili pepper. None of these guides are reliable; while small peppers are often associated with heat, large peppers are not always the mildest. Geography does not necessarily supply a clue, although the world s hottest chili peppers are said to grow in parts of East Africa. Heat generally increases as a chili is dried.
85 90 We often experience a feeling of satisfaction or contentment after eating a fiery meal, and this feeling may be due to endorphins, opiate-like compounds that are produced in the brain as the body s natural response to pain. This phenomenon may account for some 95 people s seeming addiction to hot spicy food. The hotter the chili, the more the pain, so the greater the trace amounts of endorphins produced and ultimately the greater the pleasure.
1) 2) 3) 4)
5) 6) 7)
8)
Answer Key 1) B 2) A 3) D 4) B 5) B 6) B 7) C 8) B