Demonstrating What "Light" Margarine Means Today we are bombarded with media claims for various foods that are "light". Margarine is an excellent example of a food that is available not only in its regular form but also in *light" and "extra light" varieties. The difference in these products is their water content. Differences in water content of margarines can readily he shown to students either a s a lecture demonstration or as a laboratory exercise simply by heating the margarine. One procedure is to place 14 g or one tablespoonful (usually defined as one serving) in a 50-mL graduated cylinder and to heat it by immersion in 90 "C water far about P 5 min. The heating can also he done in a microwave oven a t 20 % power for 4 min. All the margarines we have examined separate to give a clear water layer on the bottom and a yellow ail on top, with an emulsion in between. The separation is made cleaner by centrifuging the warm samples. The combinedvolumes ofthe water andemulsion layers divided by the total volume of the sample closely approximates the percent water in the product as listed on the label. The following data were obtained by heating 14-g samples of various types of Fleischmann's Margarine in a 90 "C water bath far 15 min and then centrifuging.
Fat On Label
Water On Label
(grams) Regular
(grams)
mL Water
+
Emulsion Obtained
11
3
3
Light
8
6
Extra Light
6
8
5 8
Since the "light" and "extra light" margarines are &en higher in price, the results indicate this is expeosiv, water. Reading labels can provide some interesting information. One manufacturer produces a regular margarine of only 35 calories per serving, while most regular margarines contain 100 calories per sewing. What technology has the manufacturer used to achieve this reduction? The answer is simple: a sewing was redefined as 4.7 g. Caveat emptor!
A. Donald Glover and Kenneth E. Kolb Bradley University Peoria, IL 61625
654
Journal of Chemical Education
