Sucrose polyester (SUE-krose pol-ee-ESS-ter) is an artificial fat available under the trade names of Olestra® or Olean®. The sucrose polyester molecule is quite large and cannot be absorbed or digested by the human digestive system. Since it cannot be digested, it provides no calories to one's diet. The compound is used primarily as an additive in snack treats targeted at people on a diet.
Sucrose octaoleate; sucrose ocatester
Carbon, hydrogen, oxygen
Liquid or solid
Insoluble in water; soluble in many organic solvents
Sucrose polyester is one of many compounds developed by researchers in an effort to reduce the caloric intake of people trying to lose weight. Artificial sweeteners designed for this purpose include saccharin, cyclamates, aspartame, and acesulfame K. Sucrose polyester is probably the best known and most successful artificial fat produced so far. It was developed in the late 1960s by two researchers at Procter & Gamble's Miami Valley Laboratories, Robert Volpenhein and Fred Mattson. Volpenhein and Mattson were looking for a new kind of fat that could be digested more easily by premature babies. Instead, they made a very different discovery: a compound that has many of the properties of a fat (including its flavor), but that passes through the digestive system without being absorbed or digested. Company executives immediately saw the practical application of the new compound for dieters and began a program for gaining federal approval for its use as a food additive.
The regulatory history of sucrose polyester has been very complicated, however. It was not until 1987 that Procter & Gamble had gained enough research evidence to submit sucrose polyester to the U.S. Food and Drug Administration (FDA) for its approval. Then, it took another ten years for the FDA to act on (and approve) Procter & Gamble's application. Even then, FDA approval was limited to certain specialized kinds of foods, including potato chips, crackers, and tortilla chips. The FDA's action has not been repeated in many other countries, however. For example, the United Kingdom has never approved the use of sucrose polyester as a food additive in that nation.
In fact, Procter & Gamble has faced a number of obstacles in marketing products made with sucrose polyester. A number of questions have been raised about possible health effects of the compound, and very few products containing sucrose polyester are currently available in the marketplace.
HOW IT IS MADE
Sucrose is a molecule that has eight hydroxyl (-OH) groups in it. For that reason, it can be thought of as a polyol. A polyol is an alcohol with two or more hydroxyl groups. A characteristic reaction of alcohols is that they react with acids to form esters. As a simple example, the reaction between acetic acid and ethanol produces the ester ethyl acetate:
CH3COOH + CH3CH2OH → CH3COOCH2CH3 + H2O
Since sucrose has eight hydroxyl groups, it can react with up to eight acids to form somewhat complex esters. Sucrose polyester is a compound formed by this method. It is typically made by reacting six to eight of its hydroxyl groups with long-chain acids known as fatty acids. You can see what the resulting compound is called a polyester, that is, sucrose with many ester groups on it. As their names suggest, fatty acids are acids obtained from fats. A typical fatty acid is palmitic acid, which has the formula CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2COOH.
Perhaps you can imagine what a molecule of sucrose polyester looks like. It has the basic structure of sucrose with six to eight fatty acids attached to it. The molecule is very large and cumbersome. No wonder the digestive system is unable to break it down!
A number of methods are available for reacting all or most of the hydroxyl groups in sucrose with fatty acids. In one method, the hydroxyl groups are first reacted with a much simpler acid, acetic acid (CH3COOH), forming sucrose octaacetate (octa = "eight"). The sucrose octaacetate is then reacted with a compound that has fatty acid fragments in it, such as methyl palmitate. The sucrose octaacetate is converted to sucrose polyester.
- The first commercial product in the United States to contain Olestra was the Frito Lay WOW brand of potato chips.
- One ounce of potato chips made with Olestra has 75 calories and no fat; by comparison, an ounce of regular potato chips have 150 caloriesand 10 gramsoffat.
COMMON USES AND POTENTIAL HAZARDS
Procter & Gamble had high hopes for Olestra when it was first introduced to the marketplace in the late 1990s. Public reaction was very positive at first. However, enthusiasm for the new product began to die off rather quickly. Olestra-containing products earned the company $400 million in 1998, but only two years later, sales had dropped to $200 million. One concern is that Olestra may have undesirable health effects on some individuals. These effects include bloating, diarrhea, cramps, loose stools, and urgency of defecation. The compound also appears to interfere with the absorption of certain vitamins. When the FDA approved Olestra for use in the United States, it added the requirement that vitamins A, D, E, and K also be added to counteract this effect. The future status of sucrose polyester is, at this point, somewhat in doubt.
FOR FURTHER INFORMATION
"A Brief History of Olestra." Center for Science in the Public Interest. http://www.cspinet.org/olestra/history.html (accessed on November 15, 2005).
"Fat Replacers: Olestra." College of Agricultural Sciences, Pennsylvania State University. http://pubs.cas.psu.edu/FreePubs/pdfs/uk058.pdf (accessed on December 29, 2005).
"Pass the Potato Chips!" Vanderbilt University. http://www.vanderbilt.edu/AnS/psychology/health_psychology/olestra.htm (accessed on November 15, 2005).
"Welcome to Olean Brand Olestra." Procter & Gamble. http://www.olean.com/ (accessed on November 15, 2005).