Carbohydrate Analysis

Carbohydrates are the major source of energy in our diet, and can provide energy of about 4 kcal/g or 17 kJ/g. Carbohydrates also play important roles in many physiological processes such as intercellular communications, infection processes, and certain types of cancer. Because of the essential impacts of carbohydrates to the human body, it is important to determine the types and quantity of carbohydrates in food products. Accurate measurement of carbohydrates is also required for proper nutritional labeling, detection of adulteration, food processing, quality control, economic, and many other reasons.

Lifeasible, as your trusted partner in nutritional analysis, provides high-quality analysis services for a full scope of carbohydrates, including various monosaccharide (e.g., glucose and fructose), disaccharide (e.g., maltose, sucrose and lactose), oligosaccharide (e.g., maltodextrin and prebiotics), polysaccharides (e.g., starch, cellulose, and dietary fibers), polyols (e.g., xylitol, sorbitol, mannitol, and isomalt), and others. Experts at Lifeasible will help you with reliable carbohydrate content analysis through a variety of methods including chromatographic, electrophoretic, chemical, enzymatic, and physical methods.

• Chromatographic methods

Chromatographic methods are the most powerful analytical techniques for the analysis of the identities and concentrationsof monosaccharides and oligosaccharides in foods. Carbohydrates can be separated on the basis of their partition coefficients, polarities or sizes by passing the analytes through a selected column. For the separation and identification of carbohydrates, most commonly used chromatographic methods are thin layer chromatography (TLC), high-performance liquid chromatography (HPLC), gas chromatography (GC) and HPLC/GC conjunction with NMR or mass spectrometry.

• Electrophoretic methods

Carbohydrates can be derivitized to be electrically charged (e.g.,by reaction with borates) and separated by electrophoresis according to their sizes. Carbohydrate molecules with smaller sizes will move faster in an electrical field than those with larger sizes.

• Chemical methods

The principle of chemical methods for determination of carbohydrates is based on the fact that reducing sugars (non-reducing carbohydrates can become reducing carbohydrates via hydrolyzation) can react with other components to yield precipitates or colored complexes, which can be quantified gravimetrically, spectrophotometrically, or by titration.

• Gravimetric method. This method relies on the fact that carbohydrates can be oxidized in the presence of heat, copper sulfate, and alkaline tartrate to form a copper oxide precipitate under carefully controlled conditions. The concentration of precipitate present can be determined by filtration, drying and weighing.
• Colorimetric methods. Colorimetric methods are widely used techniques for total carbohydrate content estimation. The commonly used colorimetric methods include:
• Anthrone-sulfuric acid method. This method is based on the principle that sugars can react with the anthrone reagent under acidic and boiled conditions to yield a blue-green color complex. The colored substance can be measured colorimetrically at 620 nm.
• Phenol-sulfuric acid method. The principle of this method is that phenol and sulfuric acid can react with sugar to produce a yellow-orange color product, which can be detected spectrophotometrically at 485 nm.
• Titration method. The concentration of carbohydrates can be analyzed using a certain amount of boiling copper sulfate solution and a methylene blue indicator in a flask, where the addition of reducing sugars can cause the indicator to change from blue to white once all the copper sulfate in solution has reacted. The concentration carbohydrates can be estimated through the volume of sugar solution required to reach the endpoint.
• Enzymatic methods

Enzymatic methods are ideal for determination of carbohydrates in foods due to their rapid, high specificity and high sensitivity. The principle of enzymatic methods used to determine carbohydrates relies on the ability of enzymes to catalyze specific reactions. The concentration of the end product and/or the initial rate of the enzyme-catalyzed reaction are commonly used to determine carbohydrate concentration.

• Physical methods

Due to the variation of carbohydrate concentration in food, some physicochemical characteristics of the food may change, which can be determined by various physical methods such as polarimetry, refractive index, infrared, and density.

• Polarimetry method. This method is depended on that carbohydrate molecules contain an asymmetric carbon atom which has the ability to rotate plane polarized light. The concentration of the carbohydrate molecules in solution is related to the extent of polarization and can be determined by the calibration curve.
• Refractive index (RI) method. The refractive index (n) of a material is determined by the velocity of light in a vacuum divided by the velocity of light in the material (n = c/c_m). The refractive index of a carbohydrate solution can be determined by measuring the angle of refraction (r) and angle of incidence (i)at a boundary with quartz with known refractive index (sin(i)/sin(r) = n₂/n₁). RI can be used in combination with HPLC, which allows the determination of alcohols, glycols, and aldehydes contents.
• Infrared method. This method is based on the fact that carbohydrates contain molecular groups that can absorb infrared radiation at specific wavelengths where none of the other major food constituents absorb. This is a rapid, non-destructive method for carbohydrate analysis.
• Density method. This technique is routinely used in industry for the determination of carbohydrate concentrations of juices and beverages. It relies on the fact that the density of aqueous solutions increases as the carbohydrate concentration increases.

Our carbohydrate routine research aims to deliver accurate carbohydrate testing with quick turn-around time and high sensitivity. Work closely with Lifeasible, you will benefit from our tailored high-quality services. For questions or inquiries, please feel free to contact us.