What is Sugar Alcohol?
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Sugar alcohols are organic compounds which are derived from the sweet tasting soluble carbohydrates and contain one -OH group attached to each carbon atom of the molecule. Sugar alcohols are white, water soluble solid compounds. They can occur naturally and can be synthesized by various methods at industrial level.
On consumption, sugar alcohol gives a sweet taste and contributes fewer calories than other sugars. That is why they are extensively used in the food industry. You will be surprised to know that nowadays, most of the candies available in the market do not contain sugars due to health concerns and increasing obesity problem among children. Instead, they are composed of sugar alcohols.
Sugar alcohols come under the class polyols as they contain many hydroxyl groups.
Examples of Sugar Alcohols
Erythritol, Xylitol, mannitol and sorbitol are common examples of sugar alcohols. They are 60-70% as sweet as general sugar but give lesser calories than sugars.
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General Chemical Structure of Sugar Alcohols
They have following general chemical formula – HOCH2(CHOH)nCH2OH
As you can see in the general formula of sugar alcohols that sugars have two fewer hydrogen atoms than sugar alcohols. As sugar alcohols are derived from pentose or hexose sugars so they have 5-6 carbon atoms in the chain and as discussed above they have one hydroxyl group attached to each carbon atom. Sugar alcohols generally are not found in cyclic structures. Although on dehydration sugar alcohols give cyclic ethers.
Synthesis of Sugar Alcohols
Sugar alcohols can be obtained naturally and can be synthesized as well. For example, erythritol is sugar alcohol and can be obtained by the fermentation of glucose and sucrose sugars. While mannitol is produced by hydrogenation of sugars in presence of spongy nickel catalyst. Sorbitol sugar alcohol is also produced as mannitol.
HOCH2CH(OH)CH(OH)CH(OH)CH(OH)CHO + H2 → HOCH2CH(OH)CH(OH)CH(OH)CH(OH)CHHOH
You can see in the above reaction that sugar contains two hydrogen atoms less than sugar alcohols.
Characteristics of Sugar Alcohols
Sugar Alcohols Show Following Characteristics –
They are not as sweet as general sugars and do not contain as many calories as sugars.
Their metabolism is not possible by oral bacteria.
They do not turn brown in color on heating like general sugars.
Dissolution of sugar alcohols is an endothermic reaction.
They give a cooling sensation on consumption.
They do not completely get absorbed into the bloodstream. Their rate of absorption is 50% slower than sugars.
Health Effects of Sugar Alcohols
Sugar alcohols give many advantages over general sugars. They are replacing sugars in the food due to their low calories and sweet taste. Sugars cause tooth decay while sugar alcohols do not contribute to tooth decay as they cannot be metabolized by oral bacteria. Even xylitol sugar alcohol prevents tooth decay.
They are absorbed at a lower rate than sugars in the bloodstream. So, they are perfect for diabetic patients. As they have less impact on blood sugar level. Many sweet food items which are prepared for diabetic patients use sugar alcohols as sweeteners. Although unabsorbed sugar alcohols may cause diarrhoea and vomiting, when consumed in insufficient quantities. It happens due to osmotic effects.
Uses of Sugar Alcohols
Sugar alcohols are widely used in many industries such as food and pharmaceuticals etc. Few of its uses are listed below –
They are widely used as food additives. As they are sweet in taste and generate less calories.
They are used to reduce the aftertaste of many sweeteners.
They do not cause tooth decay and help in prevention of tooth decay.
They are widely used by diabetic patients in their sweet food items.
Their glycaemic index or GI is low, so they help in maintaining the blood sugar level.
Many studies on rats show that xylitol can prevent osteoporosis. As it increases bone volume and mineral content.
Xylitol can increase collagen production so it can help to make you skin healthy.
Various sugar alcohols are being used in baked food items, candies, chewable vitamins, cough syrups, frostings, ice creams, mouthwashes, toothpastes etc.
They are used in the medicines related to eight management.
This ends our coverage on the topic “Sugar alcohols”. We hope you enjoyed learning and were able to grasp the concepts. We hope after reading this article you will be able to solve problems based on the topic. If you are looking for solutions of NCERT Textbook problems based on this topic, then log on to Vedantu website or download Vedantu Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.
FAQs on Sugar Alcohol
1. What exactly are sugar alcohols from a chemical standpoint?
From a chemical standpoint, sugar alcohols, also known as polyols, are organic compounds derived from sugars. They are a type of polyhydric alcohol, meaning they contain multiple hydroxyl (-OH) groups. Specifically, they are formed by the reduction of the aldehyde or ketone group in a sugar molecule to a hydroxyl group. Despite the name, they are neither sugars nor alcoholic beverages. They are naturally present in small amounts in fruits and vegetables but are commercially produced for use in sugar-free and low-calorie foods.
2. What are the main benefits of using sugar alcohols instead of regular sugar?
The primary benefits of using sugar alcohols as sugar substitutes include:
- Lower Calorie Content: They are not completely absorbed by the body, providing fewer calories than regular sugar (sucrose).
- Reduced Glycemic Impact: They cause a smaller and slower increase in blood glucose and insulin levels, making them a suitable option for people with diabetes.
- Non-Cariogenic Properties: Oral bacteria cannot metabolise sugar alcohols easily, which means they do not contribute to tooth decay.
- Bulking Properties: They provide texture and volume to foods, similar to sugar, which is essential in baking and food manufacturing.
3. What are some common examples of sugar alcohols found in food products?
Some of the most common sugar alcohols used in the food industry include:
- Sorbitol: Often used in sugar-free candies, gums, and diabetic food products.
- Mannitol: Used as a dusting powder for chewing gum to prevent sticking and in pharmaceutical applications.
- Xylitol: Commonly found in sugar-free chewing gum, toothpaste, and mouthwash due to its pleasant taste and dental benefits.
- Erythritol: Popular in low-carb and keto-friendly products because it has almost zero calories and is generally well-tolerated digestively.
- Maltitol: Used in sugar-free chocolates and hard candies for its sugar-like properties.
4. How are sugar alcohols chemically different from regular sugars like glucose?
The key chemical difference lies in their functional groups. Regular sugars like glucose are monosaccharides that contain either an aldehyde (-CHO) group (making them an aldose) or a ketone (C=O) group (making them a ketose). Sugar alcohols are formed when these functional groups are reduced to a hydroxyl (-OH) group. For example, the reduction of the aldehyde group in glucose results in sorbitol. This structural change prevents them from being metabolised in the same way as sugars, leading to their unique properties.
5. Do sugar alcohols contain ethanol, the alcohol found in beverages?
No, sugar alcohols do not contain ethanol. The term 'alcohol' in their name refers to their chemical structure, specifically the presence of hydroxyl (-OH) groups, which is a characteristic of all alcohols in organic chemistry. Ethanol has a simple structure (CH₃CH₂OH), while sugar alcohols are complex polyols with multiple hydroxyl groups attached to a longer carbon chain. They do not cause intoxication or have the pharmacological effects associated with alcoholic beverages.
6. Why are sugar alcohols often considered a better alternative for people with diabetes?
Sugar alcohols are recommended for individuals with diabetes because of their minimal impact on blood sugar levels. They are either partially or not absorbed in the small intestine. This slow and incomplete absorption means there is a significantly lower and more gradual rise in blood glucose and insulin compared to the sharp spike caused by regular sugar. This property is measured by the glycemic index (GI), which is much lower for sugar alcohols than for sucrose.
7. What are the potential side effects of consuming too many sugar alcohols?
The most common side effects are related to the digestive system. Since sugar alcohols are not fully absorbed, consuming them in large quantities can lead to an osmotic effect, where water is drawn into the large intestine. This can result in:
- Bloating
- Abdominal gas
- Stomach cramps
- Diarrhoea or a laxative effect
8. How is a sugar alcohol like sorbitol commercially produced from glucose?
Sorbitol is commercially produced from glucose through a chemical process called catalytic hydrogenation. In this reaction, an aqueous solution of glucose is treated with hydrogen gas at high pressure and temperature in the presence of a metal catalyst, typically nickel. The catalyst facilitates the addition of hydrogen across the double bond of the aldehyde group (-CHO) in glucose, reducing it to a primary alcohol group (-CH₂OH). This converts the glucose molecule into sorbitol (also known as glucitol).
