Chemistry for Everyone
Science of Food and Cooking: A Non-Science Majors Course Deon T. Miles* and Jennifer K. Bachman Department of Chemistry, Sewanee: The University of the South, Sewanee, TN 37383-1000; *
[email protected] Almost 30 years ago, Simek and Pruitt asked these questions concerning the design of a chemistry course for nonscience majors: What chemistry should we teach people in the arts, humanities, and social sciences? What topics will so excite students that they will abandon the “I’m-just-taking-it-for-therequirement” syndrome? What laboratory experiences will be so vivid as to mark their minds indelibly? What will inspire them to work creatively in a field remote from their specialty? In their article (1), Simek and Pruitt described the lecture, laboratory, and student projects in a food chemistry course designed for non-science majors at their institution. Additionally, they made the following statement: “We encourage others who face giving a chemistry course for non-science majors to choose a topic in the area of food. The topic is naturally captivating and inspires enthusiasm rather than dread.” We have successfully taken on this challenge. Recently there has been emphasis on the science of food and cooking in popular literature and media. Several books, including Harold McGee’s On Food and Cooking (2) and Robert L. Wolke’s What Einstein Told His Cook series (3), have focused on the science involved with a part of everyday life that is taken for granted. In addition to these books (and selected others; ref 4), the Food Network produces a television series, Good Eats, hosted by Alton Brown, that focuses on the science behind food and cooking. These have inspired us to teach a non-science majors course involving the science of food and cooking. Students who feign disinterest in chemistry are sometimes unaware of the extent to which chemistry already touches their lives. Students who claim to be unable to “do chemistry” may not recognize their own applied knowledge of chemical phenomena. The major impetus for this course is to teach students basic scientific concepts within the context of the foods they eat every day. After taking this course, students should have a new appreciation for the foods they eat, the science behind their favorite foods, and even some helpful tips to prepare foods properly. This course provides important information about food and cooking that students can use throughout their lives. Students learn what happens to the food they prepare when certain ingredients are added or when certain outside stimuli interact with the food. For example, students will understand why green beans change color (from bright green to dull green) when cooked for a long time (results from a change in the structure of the chlorophyll). Course Description In the sciences, there is much controversy over the distinction between courses for science and non-science majors (5). Our institution requires every student to complete two science courses (one of them with a laboratory) as part of the general education curriculum. With this in mind, it is important to emphasize that our course broadly describes the science of food and cooking, not just the chemistry of food and cooking. Concepts from biology, physics, and biochemistry are incorporated, even
though the course is classified as a chemistry course. Within chemistry, this course spans organic, physical, solid state, materials, and industrial chemistry. While it is difficult to omit certain topics from a chemistry course, this course was designed to play down some concepts and emphasize others. Topics that were specified as important in previous studies (6) include acids and bases, atomic structure, bonding, equilibrium, intermolecular forces, and solution chemistry. The course was taught over 28 class periods, each 75 minutes long. Teaching methods included lecture, instructor– student discussion, instructor demonstrations, and video instruction. The primary text was Harold McGee’s On Food and Cooking (2). Students were periodically given ancillary readings (available online) to break the monotony of solely reading a textbook. Students viewed a Good Eats episode at the end of each lecture to reinforce concepts. Students were encouraged to take notes during both the lecture and the viewing of the episode (7). Since at times it was difficult to take notes during the viewing, students were directed to a devoted fan’s Web site (8) that contained transcripts of each episode. In each Good Eats episode, host Alton Brown combines history, anthropology, chemistry, humor, and food. He explains the historical origins, the cultural significance, the combination of ingredients, the modern appliances that are used, and preparation secrets of success for every dish prepared. For example, in the episode “Three Chips for Sister Marsha”, the history behind the famous Toll House chocolate chip cookie recipe is explained. Three versions of cookies are prepared (thin and crispy, puffy, and chewy), with particular attention to the difference in appearance and texture as a result of variations from the original recipe. For example, an increase in the quantity of baking soda will result in a higher set temperature, which produces flatter cookies. Additionally, a higher ratio of white to brown sugar results in a crispier cookie. The use of cake flour (which has a lower protein content) instead of all-purpose flour will make a softer cookie. A chewy cookie is produced by melting the butter during the creaming step. A typical Good Eats episode highlights all of these aspects of food preparation in approximately 22 minutes. Lecture is the primary teaching method. The strengths and weaknesses of conventional lecture have been discussed in depth (9). In addition to disseminating information efficiently, lecture enables students to exercise their own flexibility in learning by different methods. Aside from class lecturing, students had opportunities to discuss controversial issues. For example, students discussed the pros and cons of different food pyramids, as well as the advantages and disadvantages of food faddism. Instructor demonstrations are a key teaching method. For example, when discussing the concept of freezing point depression, homemade ice cream is prepared using an ice–salt mixture to chill the mixed ingredients. Another example (from physics) involved students investigating the elastic and plastic properties of bread dough. Students were given a small sample of bread dough, and they considered how much stress and strain they could apply to the dough before it would fracture.
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Chemistry for Everyone Table 1. Outline of Weekly Lecture Topics and the Highlighted Scientific Concepts Weekly Topics
Scientific Concepts
Introduction
Scientific method, atomic structure, bonding, polarity, electronegativity, phase transitions
Oil and Water
Structural formulas, hydrocarbons, cis–trans isomers, solubility, pH, hydrogen bonding
Cooking Methods and Utensils
Heat, temperature, electromagnetic radiation, conductivity, crystallinity
Milk and Dairy Products
Bacteria, mold, fermentation, symbiosis, colloids, colligative properties
Eggs
Reproduction, protein denaturation, Charles’s law
Meat
Protein structure, anatomy, food-borne infections
Fruits and Vegetables
Photosynthesis, plant cell structure
Herbs and Spices
Solubility, volatility
Chocolate and Cookies
Proteins, crystal structure
Sugars
Colligative properties, crystallization
Seeds
Symbiosis, extraction, water quality
Bread
Elasticity, plasticity, fermentation, water quality
Coffee, Tea, Beer, and Wine
Fermentation, distillation, water quality, enzymes, extraction, intermolecular forces, capillary action
Table 2. Scientific Method Described in the Context of Food and Cooking Scientific Method Categories
Corresponding Questions and Relationships
Observations
Noticing and eating food at restaurants; Reading cookbooks or food-related magazines
Defining the Problem
How is the particular dish made?; Is the dish worth preparing?
Forming the Question
How do I make the dish?
Investigating the Known
Reading cookbooks and recipes; Communication with others
Articulating the Expectation
Anticipated results from combining ingredients and cooking under set of specified parameters
Carrying Out the Study
Combine ingredients and cook food under set of specified parameters
Interpreting the Results
How did the dish taste?; What was the appearance of the dish?; Were there any problems in preparation?
Reflecting on the Findings
How can the dish be improved?
Communicating the Findings
Report results with others
Table 1 lists topics covered and the scientific concepts emphasized. For each topic, particular attention was paid to the health effects of consuming the food of interest. Since, in some instances, the discussion of health effects could be controversial, care was taken to provide extensive background information and research to support statements made by the instructor. Introduction The expectations for the course were articulated, and students were asked to express their expectations through oral and written submissions. Students were introduced to the scientific method, using the Inquiry Wheel (10) as a model. One of our first discussions centered on thinking about the scientific method in the context of food and cooking (Table 2). The close similarities between scientific articles and cooking recipes were discussed (Table 3). The term diet was defined, followed by a critique of different food pyramids designed to help establish dietary guidelines. The 1992 Food Pyramid (11), 2005 MyPyramid (12), and Healthy Eating Pyramid (13) were compared. Discussions of the various food pyramids centered on the food types of the pyramid and the authors and sponsors of the pyramids. Students were encouraged to challenge government-sponsored propaganda about dietary guidelines. This exercise will hopefully persuade students in the future to critique information that they obtain 312
from the media and other outlets, instead of blindly accepting statements at face value. Students navigated a portion of the periodic table, and learned basic chemical structures and functional groups (e.g., sugars, alcohols) in foods. Understanding the concept of molar mass was important so that smaller molecules (which are more volatile and contribute to aromas) can be distinguished from larger ones. Oil and Water The relationship between this immiscible duo allowed for teaching concepts of density, solubility, dissolution, and polarity. Students were asked to draw basic organic structures, such Table 3. Similarities between Scientific Articles and Cooking Recipes Scientific Article
Cooking Recipe
Vessels and glassware
Utensils and cookware
Instrumentation
Appliances
Reagents (and amounts)
Ingredients (and quantities)
Sample preparation
Mixture preparation
Methods to determine precision and accuracy
Methods to determine doneness
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Chemistry for Everyone
as those of the common fatty acids. The recent food controversy over trans fatty acids was also discussed. Water is such a vital (and substantial) component of food that special attention was given to its description, especially how it behaves differently from most substances (e.g., why ice floats in liquid water while many solids sink). The importance of water’s high specific heat and latent heat of vaporization was highlighted in terms of its advantage as a cooking medium. Additionally, common foods and kitchen chemicals were classified as either acids or bases when the pH scale was introduced. Cooking Methods and Utensils Cooking is providing heat to food in various fashions, so the different methods of heat transfer were explored. A thorough explanation of the oft-confusing difference between heat and temperature was addressed, as well as how temperature and molecular motion are related. Heat capacity, a concept that is related to how quickly food is cooked and what type of utensil is used, was discussed. Students learned the regions of the electromagnetic spectrum that are important for cooking (e.g., microwave, infrared). The different metals that are used in cooking utensils were presented, as well as the technological advances in non-stick materials (e.g., silicone, Teflon). Students were allowed to examine samples of cookware materials and comment on their differences. Students were introduced to polymers by discussing the differences between silicone and Teflon. The colligative properties of freezing point depression and boiling point elevation capped the discussion of this topic. Milk and Dairy Products Students learned how yogurt, butter, and cheese are made and how bacteria are removed from these products. Lactose intolerance and enzyme function in cooking rounded out the topics covered. The discussion of lactose intolerance was illuminating, considering that the majority of the world’s population falls into this category. One lecture period was dedicated to the discussion of how ice cream is made. As a demonstration of the concept of freezing point depression, ice cream was made using two methods: (i) a conventional ice cream maker with an ice–salt slurry, and (ii) a large bowl with liquid nitrogen and rapid stirring. (The ice cream that was prepared was acquired from a recipe published by rather famous ice cream makers; ref 14.) Since ice cream is an example of a foam, a description of colloids was included. Eggs Students investigated the structure and properties of chicken eggs and learned that the egg’s white and yolk have proteins with different properties. Especially useful in this case was a demonstration where eggs were heated in an oven to different temperatures. After the shells were broken, students observed the coagulation of some proteins, while others remained unchanged. Explanation of soufflés, which depend on beating egg whites, allowed for the teaching of Charles’s law. The Good Eats episode, which centered on making soufflés, reinforced the gas laws covered. Meat An introduction to protein structure showed the relationship between amino acids, peptide bonds, and intermolecular bonds. How proteins in food denature and coagulate (either
through cooking or marinating) was covered. Students learned that the Maillard reactions provide meaty flavors to beef and poultry. Students also discovered that there are different methods to preserve meat, which usually involves removing water content. Several food controversies were highlighted, including mad cow disease, industrial farm-raised (which are genetically modified) versus free-range poultry, and meat irradiation. Fruits and Vegetables A thorough discussion of photosynthesis initiated this topic. Through the eye of a botanist, the classification of fruits and vegetables was explained. The composition and structure of plant cells was covered, as well as that of the different plant organs. Of paramount importance was cell wall construction and how it is modified during cooking. The different chemicals that provide fruits and vegetables with their characteristic colors were discussed, and students learned why some vegetables change color during cooking. The ways that some fruits ripen after being picked were covered, in addition to how enzymatic browning takes place. Herbs and Spices The five tastes (sweet, sour, bitter, salty, and savory) were described, as well as how taste buds interact with the brain to differentiate one taste from another. Concepts of solubility, volatility, and molar mass were explained in terms of describing how different food compounds interact with the nose and tongue to produce taste and flavor. As a demonstration, students were given several small vials that contained chemicals (e.g., cinnamaldehyde) with familiar herb and spice aromas (e.g., cinnamon). The students attempted to identify the different aromas in the vials, after which the students were informed that the vials contained synthetically-made chemicals that are similar to the actual chemicals that naturally occur in the different herbs and spices. Pungent chemicals (i.e., thiocyanates and alkylamides) were described, as well as how the Scoville scale was developed to determine the piquancy of chilies. Chocolate and Cookies Chocolate is “the food of the gods”, and the students learned some of its fascinating history. Students found out that many years of experimentation were vital in creating the chocolate of today. The modern process of making eating chocolate, from bean to bar, was explained, and the importance of the crystal structure of cocoa butter was emphasized during the discussion. The process of milling was introduced, with an elucidation of how flour is made from wheat. Yeast’s important role in baking was explained, and students learned how changing the ingredients (and quantities) in a chocolate chip cookie recipe affect the finished product. Sugars Students learned the differences between simple sugars (such as fructose, glucose, and sucrose), and they were introduced to all of the various sugar substitutes, including artificial sweeteners. Students were surprised by the small quantity of artificial sweeteners needed to equal the sweetness of table sugar. The concept of boiling point elevation was discussed in the context of the preparation of sugar syrup used to make confectioneries. The Good Eats screening described the cold-water candy test, a method to estimate the consistency of the desired
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Chemistry for Everyone
confectionery by dropping a sample of hot sugar solution into cold water. Additionally, students learned about diabetes and the role that sugar plays in this disease. Seeds Students learned that seed proteins are some of the main culprits of food allergies and that there are several types of starches in a seed. The symbiotic relationship between legumes and bacteria was highlighted, and the production of tofu and soy milk from soybeans was presented. Bread The science of the “staff of life” was introduced with definitions of doughs and batters and the different products that come from them, such as bread, cakes, and muffins. Differences in flour types were elucidated, as well as how yeast and gluten play vital roles in bread baking. Gluten’s role in dough formation and manipulation was examined in a hands-on experience, where students were given small portions of yeast dough to examine its elasticity and plasticity. Students learned the importance of carbohydrates in our diet and debated the recently popular Atkins diet, which emphasizes the reduction of carbohydrates. Coffee, Tea, Beer, and Wine The significant chemicals (i.e., caffeine and ethanol) in these beverages, and their effects on humans, were discussed. The process of making each of these beverages (from field to bottle) was described. A brief explanation of the distillation process was also given. The difference between cohesive and adhesive forces was used to describe the phenomenon of “legs” in alcoholic beverages (15). Since this course is taught on a typical college campus, emphasis on consuming alcoholic beverages responsibly was a focus. Student Assessment Students were evaluated using homework exercises, pop quizzes, exams (mid-term and final), journaling, and an oral presentation. Students were given a great deal of freedom in choosing a topic for oral presentation, but it had to be one that was not covered in depth during the course. This allowed the students to have a sense of enthusiasm that would be severely diminished if their topics were assigned. Presentation topics included The Energy Drink Explosion, Vegetable Oils Used as Biodiesel, Fermentation Process of Beer, Skogsstjärnan (Moonshine), Sugar Crystals & Rock Candy, and Banana Flambé. With the student journals, care was taken by the instructor to de-emphasize what would constitute a “good” diet. The instructor did not make suggestions about what one should or should not choose to eat, unless prompted by the student, nor was any feedback provided in terms of what should be a healthy caloric intake for the students. Some students did make anecdotal remarks (e.g., I did not eat breakfast because of studying for an exam) in their journals throughout the course. Homework assignments were usually a set of questions related to recently covered material. For example, students were expected to draw the chemical structures and formulas of fatty acids. This was an excellent exercise in terms of relating size and structure of molecules. Another homework assignment dealt with learning the compositions of chocolates and sugar candies. Colligative properties (e.g., boiling point elevation) were emphasized through this exercise. Quizzes and exams were given in short answer and essay format. To help 314
students who are visual learners, drawing diagrams to explain different concepts was encouraged on exams. Evaluation of Course Student feedback on the course has been positive in general. The end-of-course evaluations gave students an opportunity to provide comments. The comments were prompted by questions about the strengths and weaknesses of the course. Some of the more thoughtful comments included The course covers a wide range of very interesting topics. I think that the course should have a laboratory incorporated in it, so that students could get hands-on experience with actually preparing and cooking foods. Learning seems to be much more effective when a student is able to physically see how the science works. Hands-on work is very important to learning. Adding in actual cooking would make the class more interesting and allow students to see what they are learning. The course material was interesting, but I think more food should have been cooked (by both instructor and students). An example would be instead of a major test, everyone could bring in a dish they prepared with a little paper explaining directions, methods, and interesting facts about the food they prepared. This class is really great in that you get to apply the knowledge learned in it to your everyday life. All of the topics were relevant and useful. The only weakness is that I wish the class had a lab component in which students really got to test and put the information to work or at least more situations where the students were able to be more hands on.
From these comments, it is clear that the course needs to incorporate a laboratory component that would involve food preparation or cooking of some nature. Students that are experiential, or kinesthetic, learners would benefit greatly from this addition to the course. Plans are currently underway to include a laboratory component in a future offering of the course. (We welcome thoughtful ideas and resources concerning the laboratory component.) Conclusion The goal of this course was to provide our non-science majors an opportunity to complete their science distribution requirement with a new and exciting course on a topic they experience daily. The understanding of the scientific concepts associated with food and food preparation was the main focus. Students learned how the scientific method can be applied to the preparation of foods. Similarities between food recipes and scientific articles were highlighted on the first day of the course, which emphasized the idea that cooking is a scientific experiment that occurs in the confines of a kitchen. Scientists use tools to help with their experiments just as people use different pieces of kitchen equipment to prepare their meals. We hope that students will think twice about the food they eat, and its methods of preparation, as a result of completing this course. Acknowledgments We would like to acknowledge the Center for Teaching at Sewanee: The University of the South for its support in the form of a Teaching & Learning Grant. We would also like to acknowledge all of the students that were enrolled in this course.
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Chemistry for Everyone
Literature Cited 1. Simek, J. W.; Pruitt, B. A. J. Chem. Educ. 1979, 56, 230. 2. McGee, H. On Food and Cooking; Scribner: New York, 2004. 3. (a) Wolke, R. L. What Einstein Told His Cook; W. W. Norton & Company, Inc.: New York, 2002. (b) Wolke, R. L. What Einstein Told His Cook 2; W. W. Norton & Company, Inc.: New York, 2005. 4. (a) Barham, P. The Science of Cooking; Springer-Verlag: Berlin, 2001. (b) Hillman, H. The New Kitchen Science; Houghton Mifflin Company: New York, 2003. (c) Corriher, S. O. Cookwise: The Hows and Whys of Successful Cooking; HarperCollins: New York, 1997. 5. Schwartz, A. T.; Bunce, D. M.; Silberman, R. G.; Stanitski, C. L.; Stratton, W. J.; Zipp, A. P. J. Chem. Educ. 1994, 71, 1041– 1044. 6. (a) Tracy, H. J. J. Chem. Educ. 1998, 75, 1442–1444. (b) Williams, D. H. J. Chem. Educ. 1987, 64, 707–709 7. DVDs of Good Eats episodes may be purchased from the Food Network Web site at http://www.foodnetwork.com/food/show_ea (accessed Nov 2008). 8. Good Eats Fan Page. http://www.goodeatsfanpage.com (accessed Nov 2008). 9. (a) Cronin Jones, L. L. J. Coll. Sci. Teach. 2003, 32, 453–457. (b) Lord, T. R. J. Coll. Sci. Teach. 1999, 29, 59–62. (c) Ward, R. J.;
Bodner, G. M. J. Chem. Educ. 1993, 70, 198–199. 10. Robinson, W. R. J. Chem. Educ. 2004, 81, 791–792. 11. Shaw, A.; Fulton, L.; Davis, C.; Hogbin, M. Using The Food Guide Pyramid: A Resource for Nutrition Educators. http://www. nal.usda.gov/fnic/Fpyr/guide.pdf (accessed Nov 2008). 12. MyPyramid.gov: Steps to a Healthier You. http://www.mypyramid.gov (accessed Nov 2008). 13. Willet, W. C.; Skerrett, S. K. Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating; Free Press: New York, 2005. 14. Cohen, B.; Greenfield, J.; Stevens, N. Ben & Jerry’s Homemade Ice Cream & Dessert Book; Workman Publishing Company: New York, 1987. 15. Silverstein, T. P. J. Chem. Educ. 1998, 75, 723–724.
Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2009/Mar/abs311.html Abstract and keywords Full text (PDF) with links to cited URLs and JCE articles Supplement Scientific concepts highlighted in the course Course syllabus and schedule Ancillary readings Lecture slides
JCE Concept Connections: Science of Food and Cooking Miles and Bachman present a one-semester course for non-science majors utilizing the science of food and cooking as the focal point. The authors provide detailed materials in the online supplement to aid other instructors who are interested in implementing a similar course. This Journal can also serve as a source to help instructors collate information. JCE offers a wealth of materials for teaching and learning chemistry that you can explore at our Web site, JCE Online (http://www.jce.divched.org). Below, Arrietta Clauss of the Editorial Staff suggests additional resources that are available through JCE for exploring food science. Since 2000 the Journal staff has been publishing a feature entitled “JCE Resources” on various topics. In the October 2000 issue, Erica Jacobsen published a resource article highlighting materials on food chemistry found in past issues of JCE (http://www.jce. divched.org/Journal/Issues/2000/Oct/abs1256.html). This article lists classroom activities, articles, and software publications useful for teaching the science of food. The Journal also lists textbooks in various fields in the ChemEd Resource Shelf section at http://www.jce.divched.org/JCEWWW/ Features/CERS/index.html. The Food Chemistry section lists 10 textbooks including Food: The Chemistry of its Components, 4th ed., by T. P. Coultate; Springer, 2002; Kitchen Chemistry by T. Lister and H. Blumenthal, Springer, 2005; and Food Chemistry: A Laboratory Manual by D. D. Miller, Wiley, 1998. Since 1995 Hal Harris has recommended and described contemporary books and articles about topics that may be helpful to chemistry instructors. The feature is called Hal’s Picks at http://www.jce.divched.org/JCEWWW/Features/HalsPicks/index.php. Searching on food resulted in 11 books and articles, including “Naturally Dangerous: Surprising Facts about Food, Health, and the Environment” by M. Gladwell in The New Yorker, Sep 10, 2001; “Why McDonald’s Fries Taste So Good” by E. Schlosser in The Atlantic Monthly, Jan 2001; “Department of Food Science—The Search for Sweet: The Tricky Technology of Sugar Substitutes” by B. Bilger in The New Yorker, May 22, 2006; That’s the Way the Cookie Crumbles: 62 New Commentaries on the Fascinating Chemistry of Everyday Life by J. Schwarcz, ECW Press, 2002; The China Study: The Most Comphrehensive Study of Nutrition Ever Conducted by T. C. Campbell and T. M. Cambell, II, Benbella Books, 2005. Finally on the JCE Web site there is a link to the National Science Digital Library (NSDL. http://nsdl.org/). This site also has resources that pertain to food chemistry. By searching on “food chemistry” in the K–12 tab, the Kitchen Science Wiki page comes up with some good resources, including The Accidental Scientist at http://www.exploratorium.edu/cooking/ and Food and Science: Cook and Eat Chemistry at http://www.uen.org/utahlink/lp_res/nutri375.html.
Explore the wealth of JCE resources.
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