Determination of total carbohydrates by anthrone method. Carbohydrates are the important components of storage and structural materials in the plants. Recently, Morse4 and Morris5 have described the use of anthrone for the quantitative estimation of carbohydrates. This method is both quicker and. The precise method of carbohydrate isolation depends on the carbohydrate type, solution as this would cause an underestimation of the carbohydrate content. The Anthrone method is an example of a colorimetric method of determining.

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To estimate the amount of carbohydrate present in the given sample by using Anthrone method Principle: The reducing sugars in the carbohydrate solution react with the copper sulfate present in the flask.

This method has been officially sanctioned by the AOAC and is widely used in the food industry to determine the fiber content of a variety of foods. The basis of many fiber analysis techniques is therefore to develop a procedure that mimics the processes that occur in the human digestive system.

This method is therefore useful only when one knows the type of carbohydrates present, but not their relative concentrations. Physical Methods Many different physical methods have been used to determine the carbohydrate concentration of foods. Alternatively, the water-soluble and water-insoluble fiber components can be determined by filtering the enzymatically digested sample. The basic principle of this method is to isolate the fraction of interest by selective precipitation and then to determine its mass by weighing.

The concentrations of glucose and fructose can then be determined by the previous method. Immunoassays Immuoassays are finding increasing use in the food industry for the qualitative and quantitative analysis of food products. The basic units of carbohydrates are Monosaccharides. Cellulose occurs in all plants as the principal structural component of the cell walls, and is usually associated with various hemicelluloses and lignin.

More sophisticated instrumental methods are capable of providing information about the molecular structure of carbohydrates as well as their concentration, e. These methods rely on their being a change in some physicochemical characteristic of a food as its carbohydrate concentration varies. Water extracts of many foods contain substances that are colored or produce turbidity, and thus interfere with spectroscopic analysis or endpoint determinations.


In natural foods, such as legumes, cereals or tubers, the starch granules are usually separated from the other major components by drying, grinding, steeping in water, filtration and centrifugation.


There is a linear relationship between the absorbance and the amount of eshimation that was present in the original sample.

Major Components of Dietary Fiber Cell Wall Polysaccharides Cellulose occurs in all plants as the principal structural component of the cell walls, and is estimqtion associated with various hemicelluloses and lignin.

The concentration of precipitate present can be determined gravimetrically by filtration, drying and weighingor titrimetrically by redissolving the precipitate and titrating with a suitable indicator.

Commonly occurring hexoses in foods are glucose, fructose and galactosewhilst commonly occurring pentoses are arabinose and xylose. The carbohydrates are stored as free sugars and polysaccharides.

Classification of Carbohydrates Monosaccharides Monosaccharides are water-soluble crystalline compounds.

In addition, GC requires that the samples be volatile, which usually requires that they be derivitizedwhereas in HPLC samples can often be analyzed directly.

The glucose is then separated from insoluble fiber by filtration or separated from total fiber by selective precipitation of the fiber with ethanol solutions. Analysis of Fibers Over the past twenty years or so nutritionists have become aware of the importance of fiber in the diet. Manufacturers of these csrbohydrate provide detailed instructions on how to carry out the analysis.

Consumption of significant quantities of dietary fiber has been shown to be beneficial to human nutrition, helping reduce the risk of certain types of cancer, coronary heart disease, diabetes and constipation.

Anthrone Method for Determination of Carbohydrate

For this reason many food scientists believe that its use should be discontinued. In addition, to monosaccharides and oligosaccharides various other small molecules may also be present in the alcoholic extract that could interfere with the subsequent analysis e. Monosaccharides and oligosaccharides are metgod in alcoholic solutions, whereas proteins, polysaccharides and dietary fiber are insoluble.

Starch is the most common digestible polysaccharide found in foods, and is therefore a major source of energy in our diets. Prior to analysis, the alcohol can be removed from the solutions by evaporation under vacuum so that an aqueous solution of sugars remains. Some polysaccharides can carbohydfate digested by human beings and therefore form an important source of energy e. A wide variety of polysaccharides occur in foods. Specific enzymes are added to the starch solution to breakdown the starch to glucose.

Colorimetric Methods The Anthrone method is carbohgdrate example of a colorimetric method of determining the concentration of the total sugars in a sample.

Many different physical methods have been used to determine the carbohydrate concentration of foods. By carrying out measurements at a number of different specific wavelengths it is possible to simultaneously determine the concentration of carbohydrates, proteins, moisture and lipids. A clear aqueous solution of the carbohydrates to be analyzed is placed in a test-tube, then phenol and sulfuric acid are added. It is possible to determine the concentration of both non-reducing and reducing sugars by carrying out an analysis for reducing sugars before and after hydrolyzation.


It is usually necessary to remove these components prior to carrying out a carbohydrate analysis. The disadvantages of this method are i the results depend on the precise reaction times, temperatures and reagent concentrations used and so these parameters must be carefully controlled; ii it cannot distinguish between different types of reducing sugar, and iii it cannot directly determine the concentration of non-reducing sugars, iv it is sucseptible to interference from other types of molecules that act as reducing agents.

The concentration of maltose and sucrose disaccharides in a sample can be determined after the concentration of glucose and fructose have been determined by the previous method. Carbohydrates can also be separated by electrophoresis after they have been derivitized to make them electrically charged, e.

Determination of Carbohydrate by Anthrone Method

Immuoassays are finding increasing use in the food industry for the qualitative and quantitative analysis of food products. Titration Methods The Lane- Eynon method is an example of a tritration method of determining the concentration of reducing meghod in a sample. Polysaccharides can be classified according to their molecular characteristics e.

The maltose and sucrose are broken down into their constituent monosaccharides by the enzyme a- glucosidase: A solution of the derivitized carbohydrates is applied to a gel and then a voltage is applied across it.

If there are no other components present in the solution that would interfere with the analysis, then the starch concentration could be determined using physical methods, e. Sample Preparation The amount of preparation needed to prepare a sample for carbohydrate analysis depends on the nature of the food being analyzed. Like the other methods it is non- stoichemetric and therefore it is necessary to prepare a calibration curve using a series of standards of known carbohydrate concentration.

The two methods most commonly used to determine carbohydrate concentration are: This method determines both reducing and non-reducing sugars because carbouydrate the presence of the strongly oxidizing sulfuric acid.