Background Information and Teacher Page
Mankind has faced two major challenges to its survival: an adequate food supply and disease. Often the two worked synergestically causing illness and death. Spoiled food reduced the peoples caloric intake, weakened their immune system and made them susceptible to food-borne and environmental pathogens. Over the millenia our ancestors have, by trial and error, developed processes to protect their food supplies and their health.
Today there is a renewed interest in herbal remedies and alternative medicines. Ethnobotanists are scouring the tropical rainforests and consulting with shamans to preserve the knowledge of medicinal properties of plants.
The following inquiry lab will allow your students to discover the importance of biodiversity, develop microbiological skills, and reinforce their understanding of the scientific method.
Enclosed in the instructor's guide are:
Please feel free to revise or use any part of this lab that you deem appropriate for your classes. We would appreciate any constructive feedback you might have.
Background Information: History of Herbs and Spices
Today we take for granted the variety of herbs and spices that are available. It is a simple and economical task to go to the supermarket and pick up whatever is needed to make a meal. As interest in exotic cuisines increases, the demand for spices also grows.
The history of herbs and spices is very colorful. For example, the discovery of America was related to the pursuit of spices from the Orient. Originally the overland trade routes extended from Asia to the Mediterranean and Europe. The spice trade expanded when sailing vessels found new trade routes. The Arabs first developed spice trading from India to the Middle East around 2000 BC. Traders were very secretive about the source of their spices and actively discouraged competitors by spreading fantastic tales about the origin of various spices and herbs. After Ptolemy XI bequeathed Alexandria to the Romans in 80 BC, the city became the greatest commercial center in the world for trading in herbs and spices from India and the Far East. Roman trade with India weakened the Arab hold for several centuries, followed by a decline and a later revival but finally dwindled in the 6th century. The Arabian trade endured afterwards and continued through the Middle Ages. At this time Venice had become the spice trading center for Europe.
European countries, determined to break into the spice market, began the famed voyages of discovery. The Portuguese were the first to bring spices to Europe by sailing around Africa in 1501. Columbus sailed with the intent of finding a new western route to the Orient, but he never reached India or the Orient. He did, however bring back chili pepper seeds in 1493 which quickly spread across Europe. Explorations in the 1500’s found routes around South America to the Orient and India.
Several East India companies were established in the 1600’s, and they became very competitive. The Portuguese were the dominant power for about 100 years, followed by the British and the Dutch. Eventually the British conquest, colonization, and mastery of the seas gave them control over India and Ceylon while the Dutch controlled the greater part of the East Indies.
Herbs and spices were used for the flavoring of foods as well as aromatics, medicines, dyes, cosmetics, and “magical powers”. Egyptian records dating back to 2800 BC show that herbs were being prescribed as medicines. There have been more recent studies to try and isolate the active chemicals in many herbs and spices to validate medicinal uses, including antiseptic qualities. The following is some information related to the herbs and spices used in this inquiry exercise.
OREGANO is made from the dried leaves and flowering tops of several perennials from the mint family (Lamiaceae or Labiatae). The predominant species is Organum vulgare, one of the most common seasonings in Mediterranean cooking. In America oregano has became exceptionally popular in the making of pizzas. Mexican oregano, however, is more potent. It comes from the Lippia plant and is primarily used in chili powder. Organum vulgare contains thymol oil which is the main active ingredient and is used in bath oils and sachets to relieve aches and stiff joints. It is not specifically used as an antiseptic substance.
GARLIC is a bulbous perennial of the lily family (Liliaceae). The cloves or bulblets are mashed to release a strong onionlike aroma and pungent taste. It has been used for thousands of years, and some researchers believe it originated in Siberia. Garlic was present in the diets of early Romans, Greeks, and Egyptians, and its use has spread to many cultures around the world.
Studies have been done that indicate definite antibiotic properties. Allicin is one major ingredient found in the distilled oil, along with diallyl disulfide, diallyl trisulfide, and allyl propyl disulfide. Koch and Lawson in their book Garlic - The Science and Therapeutic Application of Allium sattium L and related species, have shown from their research a very strong case for antiseptic qualities with a variety of bacteria and some fungi.
CURRY is actually a blend of ground spices as used in the western world. It was originally adopted by the British colonialists in India. The basic ingredients used in most commercial curry includes turmeric, cumin, coriander, and cayenne pepper. Other spices that can be found in the variety of curries sold in Europe and the Americas include allspice, anise, bay leaves, black or white pepper, chilies, cloves, cinnamon, fennel, fenugreek, ginger, mace, mustard seed, nutmeg, and poppyseed. In traditional Indian cuisine, such spice mixtures are called masala and are prepared at home. They may be blended with water or vinegar to make a paste. The hottest curries are called sambar podi and often contain hot chilies, which is characteristic of the southern India foods. Garam masala is a milder variety of curry found in northern Indian cooking.
CINNAMON is native to Ceylon (Sri Lanka) and Burma, but it does not come from a singular source. True cinnamon (Cinnamomum zeylanicum) is a bushy evergreen tree of the laurel family (Lauraceae). It consists of the inner bark which is light brown in color and has fragrant aroma with warm, sweet flavor. It was more highly prized than gold and was used in ancient Egypt for embalming and mystical properties associated with witchcraft and magic. This was one of the spices that Columbus was pursuing when he sailed west to find the Orient. Cassia, also called Chinese cinnamon, comes from the Cinnamomum cassia plant. Commercial grade cinnamon is actually cassia or a combination of true cinnamon and cassia. The essential oil contains cinnamic aldehyde and when distilled is used in food, liqueur, perfume, and certain drugs.
CHILI consists of a large variety of different kinds
of peppers. The green or red bell pepper or sweet pepper (Capsicum
annuum grossum) is not hot at all in contrast to the jalapeno (Capsicum
annuum frutescens) which is very hot. South America is the home
for chili peppers. They derive their pungency from the capsaicin compound
which is found in the internal partitions of the plant. The
hot peppers were domesticated in present day Mexico, but are grown now
throughout the world. Red bell peppers are used
to make pimentos whereas hot chili peppers are ground and mixed with vinegar to make tobasco sauce.
Microbiologists and food companies have conducted numerous experiments to determine if the phytochemicals contained in many spices inhibit bacteria, fungi, and yeasts, and the results of these studies show that many spices have potent antimicrobial properties.
Prior to carrying out this lab the teacher must prepare 8 agar plates for each group and the bacterial cultures in nutrient broth.
The teacher should go over several concepts before the students work on the lab. Students should understand aseptic technique and be instructed on safety issues in the microbiology lab. Finally, students should know how to prepare a bacterial lawn using a glass rod spreader.
10 ml pipettes
Mortar and pestle
Test tubes with caps
Glass rod spreader
Cracked red pepper
In nutrient broth:
Bacillus subtilis, gram + bacillus
Eschericia coli, gram – bacillus
Staphylococcus epidermidis, gram + cocci
Serratia marcescens, gram – bacillus
Before students place antibiotic disks on the plate make sure the disks are dry. Also, make sure that the students do not flood the agar surface with too mach of the bacteria sample. This will cause the bacteria to run and not make a covered field.
Some possible extensions for this inquiry exercise are:
Bergey's Manual of Determinative Bacteriology. Holt et.al., Williams and Wilkins, 1994.
Cinnamon or Cassia? http://homecooking.miningco.com
Conley, Sunny. Chile Knights: Are Chiles Really Antibiotics? http://www.zianet.com/sunny/html/ck-9.html.
Ethnobotany Cafe. http://countrylife.net/ethnobotany
Herbs and Spices. http://www.nmnh.si.edu/garden/history/herbs
Herbs/Spices in the Italian Kitchen: Garlic. http://www.cucina.italynet.com
Jensen-Jarolin, E., Gajdzik, L., Haberl, I., Kraft, D., Scheiner, O., Graf, J. Physiologic effects of spices. Journal of Nutrition 128: (3) 577-581. March, 1998.
Koidis, P., Grigoriadis, S., Batzigs, C. Behavior of Campylobacter jejuni in broth stored at 4 degrees C with different concentration of spices (garlic, onion, black pepper). Archiv Fur Lebensmittel hygiene 47: (4) 93-95. July-August, 1996.
Microbiology. Prescott, Harley and Klein. McGraw Hill, 1999.
Pradeep, Ku, Gervani, P., Eggum, Bo. Common Indian Spices: Nutritional Comparison, Consumption and Contribution to Dietary Value. Plant Foods for Human Nutrition 44: (2) 137-148. March, 1993.
Risch, S.J. Spices: Sources, processing and chemistry.Spices 660: 2-6, 1997.
Sherman, Paul and Billing, Jennifer. Darwinian Gastronomy: Why We Use Spices. BioScience, 49: (6): 453-463. June, 1999.
State Pepper and Native Pepper. http://www.geobop.com/Eco/TX6.htm
**For background information and our lab results see links on homepage.
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