Why sucrose is not a reducing sugar

Significantly, sucrose is not a reducing sugar. Some sugars are formed by the bonding of two monosaccharides. They are known as disaccharides. The main difference between reducing and nonreducing sugar is that reducing sugars have free aldehyde or ketone groups whereas nonreducing sugars do not have free aldehyde or ketone groups.

Starch composed of amylose and amylopectin is non — reducing in nature due to unavailability of free carbonyl group in its constituent monsaccharides. Raffinose is a trisaccharide and a minor constituent in sugar beets.

No open-chain forms are possible. Because sucrose is a complex disaccharide, it is not classified as either an aldose or a ketone. Instead, it is a compound that contains both. Cow milk consists of proteins, fat, salts, and milk sugar , or lactose Columbia Encyclopedia, Because of the presence of aldehyde atomic groups in its molecular structure, glucose is an aldose sugar.

Reducing sugars are good reducing agents. Nonreducing sugars are not reducing agents. This is because reducing sugars have free aldehyde or ketone groups whereas nonreducing sugars have no such free groups. This is the main difference between reducing sugar and nonreducing sugar. Reducing monosaccharides include glucose, fructose, glyceraldehyde and gal After being oxidised they cause the reduction of the other substance and so known as reducing sugars.

Reducing monosaccharides include glucose, fructose, glyceraldehyde and galactose. It is called invert sugar because the angle of the specific rotation of the plain polarized light changes from a positive to a negative value due to the presence of the optical isomers of the mixture of glucose and fructose sugars.

Hydrolysis of Sucrose : The -OH is then added to the carbon on the fructose. The main difference between reducing sugar and starch is that reducing sugar can be either a mono- or disaccharide, which contains a hemiacetal group with a one OH group and one O-R group attached to the same carbon whereas starch is a polysaccharide, consisting of numerous glucose units joined by glycosidic bonds.

Glucose has a free aldehyde group which can be oxidized to the acidic groups. Hence, glucose is a reducing sugar. Starch and Cellulose are polysaccharides. The glucose in starch and cellulose does not contain a free aldehyde group and hence, starch and cellulose do not act as reducing sugars. If you add a non-reducing sugar, like sucrose, the reagent remains blue.

The Fehling test involves two reagents: a clear blue solution containing copper sulphate and a colorless solution containing sodium tartrate. You add both solutions to the sugar and place the entire mixture in boiling water. If the sugar is reducing, a brick red precipitate forms.

If you add sucrose or another non-reducing sugar, the mixture stays clear blue. Claire is a writer and editor with 18 years' experience. She writes about science and health for a range of digital publications, including Reader's Digest, HealthCentral, Vice and Zocdoc.

TL;DR Too Long; Didn't Read Sucrose is a non-reducing sugar because its chemical structure does not allow certain organic compounds to form a hemiacetal. Related Articles Test for Reducing Sugars. Is Sucrose an Aldose? Common Reducing Sugars. How Does a Sugar Crystal Grow?

During its reaction with the reducing sugar, the blue copper sulfate in the solution is converted into red-brown copper sulfide. It is worth mentioning here that these tests only show the qualitative analysis of reducing sugar. In the Fehling test, the solution is warmed until the sample where the availability of reducing sugar has to be tested is homogeneously mixed in water after which the Fehling solution is added. If the reducing sugar is present the color of the solution will be changed to a red precipitate color resembling rust.

This test is specifically used for the identification of monosaccharides, especially ketoses and aldoses. These tests can be used in the laboratory for the determination of reducing sugar present in the urine which can be used to diagnose diabetes mellitus.

It must be noted here that the reduction of aldehydes results in the formation of primary alcohols while the reduction of ketones gives secondary alcohols. The most common example of reducing sugar and monosaccharides is glucose. In the human body, glucose is also referred to as blood sugar. It is essential for the proper functioning of brains and as a source of energy in various physical activities.

Another reducing sugar is fructose, which is the sweetest of all monosaccharides. Galactose is another example of reducing sugar.

It is a component of lactose available in many dairy products. Moreover, the list of reducing sugars also includes maltose, arabinose, and glyceraldehyde. Carbohydrates, especially reducing sugar are the most abundant organic molecules that can be found in nature. They have a wide range of functions in biology. They provide a significant fraction of daily used dietary calories in most of the living organisms living on the earth. Also, their major role is to act as the storage of energy in living bodies.

Read: Glycolysis , Fermentation , and Aerobic respiration. Carbohydrates also serve as one of the cell membrane components and function primarily in mediating various intermolecular communications in the bodies of living organisms.

Lastly, via Maillard reactions, carbohydrates are responsible for determining the crust color and the taste of the food such as coffee, bread, and roasted food items. There are many uses of reducing sugar in our daily life activities.

In medicines, the Fehling solution has been used as a test to detect diabetes in human blood. The relative measurement of the number of oxidizing agents reduced by the available glucose makes it easy to calculate the concentration of glucose present in the human blood or urine.

Moreover, after the calculation of the exact amount of glucose present, it becomes easier to prescribe the amount of insulin that must be taken by the patients from the doctors. In food chemistry, the levels of reducing sugar in the products such as wine, juices, and sugar cane decide their quality.

Try to answer the quiz below to check what you have learned so far about reducing sugar. Reducing Sugar. Chemistry LibreTexts. Energy Technology, 8 1 , Test for Reducing Sugars. ATP is the energy source that is typically used by an organism in its daily activities. The name is based on its structure as it consists of an adenosine molecule and three inorganic phosphates. Read More. Skip to content Main Navigation Search. Dictionary Articles Tutorials Biology Forum.