Food for Thought Allen A. Denio University of Wisconsin-Eau Claire. Eau Claire, WI 54701 Charles R. Bennett U S . Borax Research, Anaheim. CA 92801 Students in general chemistry are often quite weak in problem-solving skills, particularly in dealing with units. These same students are also faced with the pressing problem of how to "eat better for less." Addressing both of these problems, students can calculate the number of Calories (1 nutritional Calorie equals 1 kilocalorie) per dollar of various foods, hased upon the price and weight of earh item. Further, they can calrulate the ounces/dollar of protein, carbohydrate, and fat for each type of f w d if the package provides theweight of each of these per ounce of the food. This type of problem solving presents some elementary calculations and also permits judgements of value. These calculations introduce the students to Calories (and calories), protein, carbohydrate, fat, density, and the difference between fluid ounces and ounces. In addition to helping develop problem-solvingskills, students can become aware of the "best buvs" in the su~ermarketsince manv. . oackaeed foods now include on the label the number of Calories per ounce plus the g r a m of orotein. carbohvdrate. and far. Most "fast food" outlets will provide nutritional information on request, or students can he directed to references that supply this information. The correlation between Calorie content and the amount of protein, carbohydrate, and fat has been discussed (1). The authors have used these t w e s of ~ r o h i e m during s the first semester of general chemist&. 0u;students have heen receptive to these "real world" calculations and often have done many more than required as they examined their own eating preferences.
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Gathering Data It was decided to evaluate eight food items in each of three areas that are called basic (minimal or no processing), health (items often preferred by persons having more than the normal interest in diet and nutrition) and processed (prepared, highly processed, or "fast"). I t was then time to wander through supermarkets to gather data. Some geographical balance was obtained since the authors reside in the Midwest and West Coast areas. Data Manipulation Several assumptions were necessary to produce the average cost per ounce values given in the table. Since vegetable oil,
1078
Journal of Chemical Education
milk, and heer are liquids and the selling price is per unit volume (fluid ounces), i t was decided to convert to the price per unit weight (ounces) requiring conversion factors (29.6 ml per fl oz, 28.4 g per 04 and the density (1.00 glml approximately for milk and beer, 0.920 g/ml for vegetable oil). T o determine the cost per ounce of eggs, normally sold by the dozen, one must use theweight of the egg less the shell. The value kven in the literature for this size eeg (large) is 54 e ( 2 ) . For bananas, sold by the pound, one must;se the weightless the peel in these calculations. The reference used a value of 60% for the edible portion (3). Hamburger is quite avariahle quantity, depending upon the grade of beef, the amount of fat, and other additives. Thus, the designation "extra lean" is used to indicate the best erade offered. usuallveround round. and the price given in the table, $0.134/oz,;;for the raw hambureer. Since even the most primitive students normally cook the; hamburger, one must &o calculate the cost/ounce~ofthe cooked item. As the normal weight loss on cooking this top grade of hamhurger is about 25%; the cost of the item rises go $0.179/oz (3). Brand names are included in the table where possible. The heer listed represents the normal type brew rather than the "light" version. The Big Maca sandwich purchased from McDonald's was transported to the laboratory and weighed (209 grams). The Twinkie" information was provided by the baker (4). Tofu, a recent product on supermarket shelves, is a fermented sovhean oroduct ( 5 ) . The second Gerticai section of the tahle, labeled Compositions. lists the Calories/oz and nercentaees of orotein. carbohydrke, and fat. The data for eggs, bananas, and hamburger are hased upon the assumptions made previously. Results I t is then possihle to combine the cost per ounce and comoositions to eenerate the third vertical section: summarv per dollar. ~ h i s k s t Calories/$ s and ounces of protein, carbohydrate, and fat/$. In each of the three categories the items are ranked in order of decreasing Calories/$. Thus, it is now possihle to observe that the least expensive source of Calories among the twenty four items is flour, followed by sugar, vegetable oil, Quaker Oatsa, and peanut butter. Note that the top three are basic and two are health items. If one is interested in inexpensive protein, flour again heads the list. The top five
D a t a a n d Results Average Cost Per Ounce
Compositions
Summary Per Dollar Cal
Basic
7.600
Flour (Gold Medal. King Midas) Sugar (C b H. Crystal) Vegetable Oil (Crisco. Wesson) Eggs (Ig. Grade A. less shell) Milk 12%) ~ a & (sun Mald. Sun Giant) Bananas iedlble pation) Hamburger, raw (exha lean)
6.100 4.600 1.400 1.000 840 690 260b
Health
2.600 1,900 1,100 690 660 470 250 69
Quaker Oatse Peanui Buiter (Jif. Skippy) Peanuis (dry roasted) (Planters) Milk (dry) (Carnation) Cheese (American) (Kran) Yogurt (plain) (Dannon)
Tofu Mushrooms (raw)
R-sed
1.600 1.500 1.200 1,200
Marshmallows (Kran) French hies (frozen) Whealiek
1.000
. ........--
..
.
0.183 0.0296'
Big Macm Beer (I2 cans) Miller. Old Style
~~~
76 14
19
12
0.6
-
4.4
.. . 460
0.8 0.2
1.2 1.5
~~~
1.0 0
Convened horn fluid ouncss to ovnoes 8 8ased upan welsh1 anw Emking.
are flour, Quaker Oatsm, eggs, dry milk, and peanut hutter, two basic and three health items. Not surprismgly, flour is the best carbohvdrate value. Other efficient sources of carbohvdrates on t h e l i s t are sugar, Quaker Oats", marshmallo&, and Frosted Flakes'. The first two basic items, flour and sugar, are each better than the next three combined! In the fat category, the leading items are vegetable oil, peanut hutter, eggs, peanuts, and French fries or potato chips. The oil, one of the basics, exceeds the sum of the next four items. If the best items in all four categories are examined, flour ranks first in three cases, sugar is second in two categories,vegetable oil ranks first and third in two categories while Quaker O a t b and peanut hutter each appear in three of the categories. Mushrooms offer very little value as a food item, unless perhaps they are growing wild and are obtained without cost (6). Thiscould he a deadly exercise, however. Hamburger and tofu are also found to he very expensive food items and perhaps heyond the reach of most student budgets. ~ e e r i as disappointment in all categories, no surprise since it is about 91%water. This information. when shared with students. has been generally unconvincing: Perhaps the 3.2 to 4.0% ethanol content is a factor. One should caution students concerning the limited nature of this studv. A balanced diet must consider other factors such as fiber, vi&ins, and minerals (7).What is presented in these tables is not intended to be comprehensive, either nutrition~
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allv - ~ - - or economicallv. In fact. the brevitv of this list of twenty-four items is certain to suggest the addition of others such as tuna fish. eranola. rice. chocolate. etc. I t is hooed that once their curiosity is aroused, students will expand upon this studv as thev sharoen their skills a t unit conversions and solving for useful relationships. This studv has demonstrated the acauisition of data. its manipulation to a more usable form andthe development of new relationshios of ereat imoortance to students concerned with obtaining t h e Lest nutrition available a t their income level. (The purchase of items in the "processed" groups is obviously not an efficient use of food dollars). These calculat use in a variety of tions are a t a level that should ~ e r m itheir introductory chemistry courses.
