BuffaloSue
Tue, Jun-08-04, 22:17
http://www.madison.com/captimes/features/75925.php
Harvest to home: Cutting carbs in sweets
By Richard Hartel
Special to The Capital Times
June 8, 2004
With the popularity of low-carb diets, there are now low-carb versions of nearly every food, from bread to chocolate and ice cream.
Regular chocolate and ice cream are definitely not low-carb products; the sugar provides much of the enjoyable eating sensation. What's a chocoholic or ice cream fanatic on a low-carb diet to do?
Replace the sugars with sugar alcohols, or polyols, and you have low-carb versions suitable for the sweet tooth on even the strictest low-carb diet.
What exactly is a polyol and why doesn't it count as a carbohydrate? A sugar molecule contains carbon, oxygen and hydrogen atoms arranged in a particular way. Sucrose, for example, has 12 carbon atoms, six oxygen atoms and 22 hydrogen atoms, whereas glucose has six, three and 12, respectively.
When a sucrose or glucose molecule is hydrogenated, meaning additional hydrogen atoms are added, they become sugar alcohols, or polyols. After hydrogenation, a sucrose alcohol, called isomalt, has 24 hydrogen atoms (carbon and oxygen are the same), and a glucose alcohol, called sorbitol, has 14 hydrogen atoms.
These molecules have significantly different properties than the sugars from which they are derived. Hydrogenation of sugars makes them much less digestible in our gastrointestinal system. Instead of 4 calories of energy per gram of sugar eaten, polyols can be as low as 1 or 2 calories per gram. Thus, there is much less available as "net carbs."
They also induce a lower insulin response than sugars, which makes them useful in sugar-free products for diabetics and others concerned with changes in the glycemic index.
Sugar alcohols also are not cariogenic, a fancy word that means they don't cause tooth decay and give us cavities. They are used widely in chewing gum for this reason, and because that's the only kind mom lets us chew.
Are sugar alcohols alcoholic? No, that's just a chemical term for the specific arrangement of carbon, hydrogen and oxygen atoms. You can eat these low-carb foods containing sugar alcohols with a good conscience and can even drive home after eating your low-carb ice cream.
Clearly, sugar alcohols have lots of advantages in our diets; but if they are so good, why haven't we seen more products made with them before now? Why have sugar-free products been primarily specialty products?
The answer is because of the pretty intense laxative effect. Sugar alcohols are not very well digested in the stomach and, being small molecules, soak up a lot of water (the osmotic effect). So they not only pass right through, they come out in a hurry. The microorganisms in the intestine also ferment the polyols, leading to gas formation (a problem similar to lactose intolerance). Eat an entire pint of low-carb ice cream covered with some low-carb chocolate and you're likely to get some exercise running to the bathroom.
Believe it or not, there are people who promote a diet based on this laxative effect. Lose 14 pounds in seven days on the Ex-Lax diet (seriously, there is a Web site that promotes this approach)! What they don't say is how dangerous such a diet is; the dehydration that accompanies consumption of such foods is a real problem that can even lead to death.
As more foods are being made with sugar alcohols, people on low-carb diets need to be careful not to eat too many of these foods. The negative consequences of eating too many polyols may offset the dietary advantages of low-carb foods.
Richard Hartel is a professor of food engineering in the University of Wisconsin-Madison food science department. He teaches courses on food processing and food engineering and researches the chemical and physical changes that take place during manufacture and storage of foods. For more information about the field of food science, contact the department (www.wisc.edu/foodsci).
Published: 8:35 AM 6/08/04
Harvest to home: Cutting carbs in sweets
By Richard Hartel
Special to The Capital Times
June 8, 2004
With the popularity of low-carb diets, there are now low-carb versions of nearly every food, from bread to chocolate and ice cream.
Regular chocolate and ice cream are definitely not low-carb products; the sugar provides much of the enjoyable eating sensation. What's a chocoholic or ice cream fanatic on a low-carb diet to do?
Replace the sugars with sugar alcohols, or polyols, and you have low-carb versions suitable for the sweet tooth on even the strictest low-carb diet.
What exactly is a polyol and why doesn't it count as a carbohydrate? A sugar molecule contains carbon, oxygen and hydrogen atoms arranged in a particular way. Sucrose, for example, has 12 carbon atoms, six oxygen atoms and 22 hydrogen atoms, whereas glucose has six, three and 12, respectively.
When a sucrose or glucose molecule is hydrogenated, meaning additional hydrogen atoms are added, they become sugar alcohols, or polyols. After hydrogenation, a sucrose alcohol, called isomalt, has 24 hydrogen atoms (carbon and oxygen are the same), and a glucose alcohol, called sorbitol, has 14 hydrogen atoms.
These molecules have significantly different properties than the sugars from which they are derived. Hydrogenation of sugars makes them much less digestible in our gastrointestinal system. Instead of 4 calories of energy per gram of sugar eaten, polyols can be as low as 1 or 2 calories per gram. Thus, there is much less available as "net carbs."
They also induce a lower insulin response than sugars, which makes them useful in sugar-free products for diabetics and others concerned with changes in the glycemic index.
Sugar alcohols also are not cariogenic, a fancy word that means they don't cause tooth decay and give us cavities. They are used widely in chewing gum for this reason, and because that's the only kind mom lets us chew.
Are sugar alcohols alcoholic? No, that's just a chemical term for the specific arrangement of carbon, hydrogen and oxygen atoms. You can eat these low-carb foods containing sugar alcohols with a good conscience and can even drive home after eating your low-carb ice cream.
Clearly, sugar alcohols have lots of advantages in our diets; but if they are so good, why haven't we seen more products made with them before now? Why have sugar-free products been primarily specialty products?
The answer is because of the pretty intense laxative effect. Sugar alcohols are not very well digested in the stomach and, being small molecules, soak up a lot of water (the osmotic effect). So they not only pass right through, they come out in a hurry. The microorganisms in the intestine also ferment the polyols, leading to gas formation (a problem similar to lactose intolerance). Eat an entire pint of low-carb ice cream covered with some low-carb chocolate and you're likely to get some exercise running to the bathroom.
Believe it or not, there are people who promote a diet based on this laxative effect. Lose 14 pounds in seven days on the Ex-Lax diet (seriously, there is a Web site that promotes this approach)! What they don't say is how dangerous such a diet is; the dehydration that accompanies consumption of such foods is a real problem that can even lead to death.
As more foods are being made with sugar alcohols, people on low-carb diets need to be careful not to eat too many of these foods. The negative consequences of eating too many polyols may offset the dietary advantages of low-carb foods.
Richard Hartel is a professor of food engineering in the University of Wisconsin-Madison food science department. He teaches courses on food processing and food engineering and researches the chemical and physical changes that take place during manufacture and storage of foods. For more information about the field of food science, contact the department (www.wisc.edu/foodsci).
Published: 8:35 AM 6/08/04