Cooking with Chemistry Arthur E. Grosser McGill University, 801 Sherbrooke St. W., Montreal. Quebec, Canada H3A 2K6 This is a critical period for chemical education. Although recent criticism of the American educational system ( 1 , 2 ) provides a long-awaited opportunity for reform, the forces of reaction are manv and vocal. An editorial in Science inveiehed against "favorite status for mathematics, science, and engineering" (3). and i t has even been sueeested that chemistrv be dropped from secondary school curr%ula in favor of biology and physici(4). Instead this author urges that chemistry instruction he offered to a much broader audience, including the very young and suggests materials particularly well suited to this task. The chemistrv of cooking and, in particular, the analysis of culinary recipes, is close t o ideal aH subject matter forthe introduction of chemistry to an audience, especially one with a neutral or negative attitude toward science:[~he newspapers rarely tire of telling us that such audiences do exist: "We seem to have created a monster in the post-World War I1 chemical revolution that we hailed as a boon. . ." (5). ". . . T h e fundamental cause of the chemical industry's public perception problem is basic fear of chemicals. . . I mean genuine phobia and anxiety" (6).] What is it about the chemistry of cooking that makes it so acceptable to a general audience?
But all of these directions have scientifically valid bases and perform necessary functions in the proper preparation of the eggs. In explaining the rationale for these directions one can invoke the folluwing chemical ideas. 1) exlatenre of m~~lerulrs 2 ) mc,ler!~laritr!lcrure a) conformation b) dependence of conformation on electrical character of medium (dissolved salts, acids, etc.) C) bonds between molecules d) localized bonding sites e) large-scale molecular structure 3) acidity and pH 4) reaction 5) reaction speed 6) temperature, temperature gradient 7) dependence of reaction speed on a) temperature b) ionic character of medium e ) sterie factors d) E . 8) precipitation, solubility, and K., 9) Boyle's Law 10) gas density, convection 11) thermal shock
1) It presents science applied to matters which are personal, nonthreatening and small-scale, in a word, "domestic." 2) It presents science as a technique which has already been used
The explanations, of course, can he a t any level of sophistication, from introduction to the concepts of molecules and temoerature to detailed considerations of orotein denaturationaand rate laws. The table gives an incomplete listing of cooking examples and their related scientific principles. What is particularly intriguing is the possibility of introducine experimentation and the scientific method as simnle demonstrations which the audience members can perform in their own homes.
It reveals to the audience that they are practicing chemists whenever they prepare a meal. 3) It is amenable to unsupervised experimentation in the home when presented in a precise manner. 4) It can be used for a lay audience ("popular science") by drawing chemistry principles from cooking experience or for an academic one ("relevance") by illustrating the principles with the examoles. i l I t can rxplam o largr number ot rrcipr dirrctim. with wly a few cvwnrfic organizing prineiplrs and thrrefore grnerntr$ a feeling of power and accomplishment in the audience For example, in recent publications (7, 8 ) we examined recipes for cooking eggs and found many directions which might a t first glance seem frivolous. Let us look a t two examples. Recipe: Hard- or soft-cooked eggs Directions: a) use eggs at room temperature h) use only old eggs (or only fresh eggs, depending on the eookbook) c) put a pinhole in the shell, hut only at the large end d) start the eggs in cold or lukewarm water e) add salt to the water fi simmer, do not boil g) rinse in cold water immediately after cooking Recipe: Poached (freehand) eggs Directions: a) use fresh eggs b) use eggs at room temperature c) cook in a shallow skillet d) have the water at a simmer, not a boil el add salt (or vinegar, or both, dependingon the cookbook) to the cooking water
362
Journal of Chemical Education
Demonstration 1 Ingredients: 3 I-in. cubes of stewing beef I cup fresh pineapple, pureed
Cut the heef into thin slices. Put the slices from one cube into '1%cup of ~ineaode~ur6eand do the same for the second set of slices. Let the third set ifslices rest bv itself in a CUD Stow onr of thr brrf-pincapplrcups in rhr refrigeraror, theother. and rhr bed alonr. at room rrmprrature Alter a day, drain and rinse a.1 the ramples Maih a portion ofeach with a fork, comparing the textures (9) Demonstration 2 Ingredients:
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Spmklr thr envrlupt- uigrlarin onw the pineapple juiw in a suw pan, plow i t u v w Ion hr.11. and stir constantly unril the gelatin dissdws lentil nogranulrsare \,isihlr,obodr ;I rnin,. Hr~wvrfnm hear and pour ("to 2 d~shrsor bowls. Take the meat hum rhe pineapple and hlend it IN,a purk or chop ir aqtinrlvaa pus~ible.1'21 uric tableipwmof the purkintouneofthe dishes ofgelatin. Chill bath gelatin preparations overnight in the refrigerator. The one with added fresh pineapple will not set (10). These two experiments are really about enzymatic proteolysis and its temoerature de~endence.hut thev also exolain a lot of recipe directions. ~ u i simple h exercisescan he fhlowed by more rigorous ones emphasizing experimental design, control
Cooking Examples of Sclentlc Scientific Topic
Cwking Example
Prlnclples Scientific Topic
Cooking Example
and hard-cooked eggs (pinholing) Kinetics poached fish and ceviche souff1C Energy of activation cooked and uncookedjams Temperature dependence of rate garlic and onion cookery quick breads cakes Enzyme reactions meat tenderizers browning of cut fruit yeast dough fresh pineapple Jell@ V a ~ o Pressure r and Phase Equiiibra high altitude cwking baking and choice of pan material IlambCing (pies, custard, cakes, cookies, etc.) hot alcoholic drinks Radiation pressure cooking Cocktails baking powder Organic Chemistry Acids and Bases flambCing peanut brinle Alcohol Organic acids fish odor, Cowl bouillon vegetable cwkery browning of roasts and barbecues pectin jams and jellies Amines sugar-starch equilibrium in potato storage red-blue vegetable colors Amino Acids indicators candy-making red-blue fruit colors Carbohydrates barbecue sauce rice color candy-making Inversion Equilibrium yeast dough potato storage temperature Le Chatelier's Principle candy-making boiled potatoes Fermentation reaction ice cream tea and coffee Crystal structure Gas-liquid equilibrium barbecue sauce K,.and solubility sugar in cocktails gray-green deposit an yolk of hard-cooked eggs Mailiard reaction roasting and grilling jams and jellies boiled potatoes vegetable cookery Carbolic acids " salad dressing candy-making Boiling point elevation mayonnaise ice cream Emulsifiers Freezing point depression emulsified sauces sherberl ethylene coloring of tomatoes mint julep Hydrocarbons cured meat Storage of live saltwater fish and shell fish Osmotic pressure meat color changes yeast dough Nitrosamines egg cookery salt-free bread Protein gelatin coffee cake oxidation denaturation ceviche Gases. Gas Laws
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of variables. renlication.. exnerimental error. and the scientific . method in general. Few people in such an audience will have personally formulated a face cream, cracked a hydrocarbon, radiodated a relic or taken a ride in a rocket, hut all of them will have cooked something. If we give them the tools to think creatively (and scientifically) about this daily activity, it may change attitudes and relieve some of the anti-scientific, anti-intellectual burden of the times. Ultimately, the success of such a proposal rests on the desire of our audience to understand the molecular activities which govern so much of their daily activities and our enthusiasm in explaining them.
Literature Cited (I) NatianalComisianon ExcellenceinEduestinn,quotDdintheNeu York 7Yms.April 27,1983,p. 1. 12) National Task Force on Education for Econnmie Growth, quoted in the New Yorh Times. M a y 5,198S.P. 1.
16) Simeral. William G.. ex-preaidenf Chemical Manufacturers Association. reported in the New York Times, June 10,1983,p. R7. 17) Grme?. A. E., T h e Culinary Alchemy of Egga." American Scknfist. 71. 129 11983). 18) Gros8er.A. E.,"TheCookbookOemder?Beaufort.Ner York. 1981,pp. 1-10. (9) "The Cookbook Decoder? p. 52. (10) "The Cookbook Decnder? p 186.
Volume 61
Number 4
April 1984
363
