Icumsa Methods Book Pdf
Blanchefle Strycker
The International Commission for Uniform Methods of Sugar Analysis (ICUMSA) is an international standards body, founded in 1897,[1][2] that publishes detailed laboratory procedures for the analysis of sugar.
The ICUMSA Methods Book[3] contains detailed instructions for analyzing raw, cane, white, beet, molasses, plantation white and specialty sugars. Among these are methods for determination of dry solids content by polarimetry, densimetry and refractometry, color (extinction coefficient at 420 nm), reducing sugars, and the presence of metals such as arsenic and copper. The Methods Book also contains polynomials and tables (derived from the polynomials)[4] which relate the refractive index of solutions of pure sucrose, glucose, fructose and invert sugar to the strength of those solutions. These are to be used with the analysis methods that characterize sugars by refractometric means but find wide application outside the sugar industry as the sucrose polynomial is built into the firmware of modern refractometers and is the basis for calibration of purely optical refractometers which read in Brix. Temperature correction factors, also derived from the polynomials, are the basis for the Automatic Temperature Compensation features found in those instruments.[5] Thus, a vintner measuring the Brix of juice from his grapes by means of a refractometer accepts a sugar content reading based on the refractive properties of sucrose despite the fact that the primary sugar in grape juice is fructose, not sucrose. This usually does not result in significant error.
The ICUMSA is constituted of representatives from national committees designated by the governments of major sugar importing and exporting countries; the votes of these representatives are weighted according to the amount of sugar their countries import and export.[6]
Sugar is important; all organisms need sugar as a source of energy. Its chemical structure is simple, encompassing all saccharides from monosaccharides, disaccharides, oligo- and polysaccharides. However, in everyday terms we think of sugar as a sweet crystalline substance obtained from various plants. It is in fact sucrose, a disaccharide consisting of fructose and glucose.
The quality of sugars is determined by a series of chemical and physical properties. This application brochure presents selected analytical methods for the state-of-the-art measurements of several sugar quality parameters using instruments by METTLER TOLEDO.
The International Commission for Uniform Methods of Sugar Analysis (ICUMSA) describe a number of methods for the colorimetric determination of filtered sugar suspensions at known concentration (Brix value).
The Kemtrak DCP007 LED process photmeter is recommended to accurately measure ICUMSA color. The Kemtrak DCP007 utilizes a proprietary dichromatic measurement technology that compensates for particulates, allowing accurate color measurement without the need for filtration.
The Kemtrak DCP007 LED process photmeter uses a high performance long life LED light source, precision optical filters and robust fiber optics that results in an ICUMSA color analyzer with outstanding performance and reliability.
Since optic fibers are used to transfer light to the measurement point and back, the measurement cell contains no electronics, moving parts or sources of heat that result in condensation on the optical surfaces. Standard measurement cells are machined in sanitary grade stainless steel with sapphire windows.
At its 2016 session in Warsaw, Poland, ICUMSA approved a set of "General Guidelines for Validating Indirect Measurement Techniques" (click here). The indirect measurement techniques are alternative techniques for measuring sugar properties, which aim to give similar results to the laboratory ICUMSA methods in the ICUMSA Methods Book.
By following the guidelines you may check whether an indirect measurement technique has the same level of performance as the laboratory ICUMSA method used to calibrate it. The guidelines present an approach to be taken to validate the indirect measurement technique in order to ensure a robust outcome.
The example used for testing and establishing the guidelines was the reflectance method of the Neltec ColourQ 2100. Two Neltec ColourQ 2100 instruments were evaluated in the range of 20 to 50 IU against the method "ICUMSA GS2/3-10 (2011) - The Determination of White Sugar Solution Colour, Official" using the guidelines in order to see whether these were sufficiently developed. According to the results of the validations applying the guidelines, it was demonstrated that the two ColourQ instruments gave equivalent results to ICUMSA GS2/3-10 (2011). After a thorough review of the guidelines and the test of the guidelines on the ColourQ instruments, the ICUMSA session decided to approve the guidelines.
According to the guidelines: "A validated calibration cannot be transferred to another instrument, factory or laboratory." Therefore, any validation established using the guidelines cannot be extended to other instruments - these have to be similarly developed following the same protocol. Each new installation must be validated based on laboratory results using the official ICUMSA method.
ICUMSA and specific products/instruments
In order to comply with ICUMSA policy on proprietary methods and equipment, it should be noted that ICUMSA does not endorse or approve specific products. All equipment used for the analysis and characterization of sugar should be properly validated according to accepted protocols.
Color measurement is originally based on comparison to existing color standards, like real examples, tables etc. The human eye was the very individual indicator for a color e.g., already being green or still being yellowish. A reproducible distinction of colors is impossible, if it is not measured under defined conditions. The visible wavelength range is around 380 to 740 nm, whereas UV and NIR cannot be seen by human eyes.
There are several color definitions, such as RGB (additive coloring) or CMYK(subtractive coloring). Beside the color itself there are parameters describing differences: brightness, saturation and gloss.
For instance, for safety and traffic signs the DIN EN ISO 7010 gives a definition of colors to be used. There are many norms with color definitions for almost any product. However, if in the industry two products should be compared to have 100% the same color, it is obvious that a precision measurement technique is needed to check for reproducible colors. The quality control is one important use case for color measurement.
If a cleaning step (CIP) is started, a color sensor can quickly identify, if colored sample is still present in the production line, or if the pipes and vessels are clean. Product differentiation is another example:
To determine if fuel, e.g., kerosene, gasoline, diesel, is contaminated or has degraded during storage time, a specific color measurement test, using the Saybolt color scale (ASTM D156, ASTM D6045), can be performed. Both ASTM methods are off-line methods. The Saybolt color scale range is from +30 (clear water / white) to -16 (dark yellow). ASTM D 1500 also describes the color testing of petroleum products.
To evaluate pollution levels in wastewater and for drinking water control, a specific color scale is used, called Pt/Co scale, APHA-Hazen Scale, or APHA Scale. Generally it is described in ASTM D 1209 for the comparison of yellow sample color intensity. The APHA color scale range is from 0 to 500 in ppm (parts per million) platinum cobalt to distilled water, what is the zero point (also called white water). The test for APHA color is performed in chemical, pharmaceutical, petroleum und plastic industries, as well as in beverage production.
This color scale describing the yellowness of transparent liquids is from 1 to 18, where 1 is light yellow and 18 is a dark brown. It was originally designed for testing resins, fatty acids, varnishes and drying oils using liquid color standards. ASTM D 1544 describes glass filters to compare with yellow colored liquids and ASTM D6045 defines the correlation to the Gardner color scale. The relationship to CIE led finally to ASTM D1544, Standard Test Method for Color of Transparent Liquids (Gardner Color Scale). The spectrophotometer method using a 10 mm path length for transmission measurement is described in ASTM D6166, Standard Test Method for Color of Naval Stores and Related Products.
For product and production control beer brewers have to measure color intensity and turbidity (haze) in EBC units, roughly darkness of a beer or wort, as well as quantifying turbidity (haze) of beer. The Standard Reference Method (SRM) and European Brewery Convention (EBC) methods have mainly replaced the "Degrees Lovibond" or "L" scale, with SRM results being approximately equal to L. The Standard Reference Method describes the use of a spectrophotometer or photometer measuring the attenuation of light at 430 nm wavelength, (blue).
With the ICUMSA methods book detailed instructions are given to analyse all types of sugars, molasses etc. For color evaluation the extinction at 420 nm wavelength is controlled at defined optical path length. Pure, white sugar absorbing less light (value 45) compared to brown sugar at value 1000 for high absorption. For the calculation of the ICUMSA value additional parameters must be tested, such as density, refraction index.
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- Color: The sugar has a white, sparkling appearance with a color rating of 45 ICUMSA units, which is the lowest in the white sugar category. This color grade is achieved through an extensive refining process.
- Granulation: It has a fine granular consistency, with granule sizes usually ranging between 0.5 to 1.0 mm. This fine granulation makes it highly soluble, a desired property for various industrial applications.
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