ICUMSA News n°39 – 2000

Message from the President

At last, after so many misfortunes, I have the pleasure in informing you that the Proceedings of the 22nd General Assembly held in Berlin are ready. It has been a long and difficult project owing to a series of mishaps including problems with computers and the disappearance of the camera-ready artwork, during its mailing from Australia to London. We have to thank very warmly the Chairman of the Publications Committee, Phil Atherton, for his hard work and patience as well as all the other people who helped him in this difficult job. The work carried out by the printer (CPL) seems to me very good and now the Proceedings are ready to be sold. In agreement with our Treasurer, Clive Shelton, we have decided that the price of the Proceedings is 75 EURO plus mailing costs, although the proceeds of the sale will probably not cover all the cost of publication. In fact, the price mentioned above is only a little over the price of the Proceedings of the 21st General Assembly with the aim of making the distribution of the book more successful. Moreover, the price is in EURO. This is due to another change which has occurred recently. IML (the publisher of the “International Sugar Journal), who was contracted for the distribution of the ICUMSA Publications, has been replaced and we have had to find a successor rapidly. Thanks to the cooperation of Dr. J. Bruhns, the distribution of the ICUMSA Publications will now be managed by Bartens, the publisher of the well-known magazine “Zuckerindustrie”. All our stock of publications, (including the Proceedings of the last sessions, the Methods Book, Supplements and, of course, the new Proceedings) are moving to Germany. Therefore, from now on, Bartens will be the official distributor although, for America and Asia, purchasers can liaise directly with “Sugar Journal” (USA) and “Sugar tech” (India) respectively. We will have to update the price of the old books, and these changes will be included in our web site in due course.

With the purpose of making easier the managing of ICUMSA publications we could consider for the future, the possibility of including them, at least partially, into a special web site to be visited after subscription or adopting the CD-rom technique. Such a project has already given rise to different reactions and I would like to receive other opinions and proposals.

In order to reduce storage costs for the older publications we intend to follow the suggestion by Dr. Pollach and send out these older books free of charge to non-profit organizations and public libraries. Postage and packaging costs will be charged only. I would be grateful if anyone who is interested in this initiative would send me his request via e-mail (  or fax +39 0532 291 168.

 Now that the Proceedings are available, I hope that Referees who have not yet started their work on their relevant Subjects can start their work, if they have not done so already. I would invite all the Associate Referees to support the program of their Referees and ask that the work is carried out without delay.

As pointed out in the last ICUMSA News, I collected the results of the ballot concerning the General Secretariat. Unfortunately, only 19 National Committees (58%) have sent back the voting paper, 17 of which were in favour. Considering the total number of vote casts (105) the positive answers represent only 55.2%. It is, of course, not sufficient for changing our “Consitution and By-Laws” so I believe that we can set aside the problem unless we receive other suggestions from the different National Committees.

Some remarks on the refractometric sucrose scale by Joachim Keitel

Referee of Subject 4

At the 16th Session the ICUMSA agreed upon a polynomial to convert the concentration of a pure sucrose solution to its refractive index. The validity range was set to concentrations between 0 and 85 % and temperatures between 18 and 40 °C. In the Report of 21st Session a table is given for the range up to 95 % concentration instead. Furthermore, the Methods Book gives the polynomial of the 16th Session (No (1) of SPS-3) plus an alternative one, which was presented at the 20th Session (No (2)). This leads to some confusion.

1. The polynomial given at the 16th Session is based on measurements of samples with concentrations between 5 and 65 % at temperatures between 19 and 40 °C. All values outside these ranges are extrapolated.

2. For the wavelength of 589 nm, polynomials (1) and (2) in SPS-3 (1994) of the Methods Book differ from each other by less than 0.000006 in the refractive index even

far outside the range, i.e. up to 100 % concentration and 80 °C. For all technical applications both polynomials may thus be regarded as identical.


a. In polynomial (1) the wavelength has to be given as 589 nm, while in (2) it is 589.3 nm.
b. Polynomial (1) gives the refractive index against vacuum, (2) the refractive index against air at 20°C.

b. c. There is a mistyped sign for one coefficient of polynomial (1) in the Methods Book: -0.0000523892 must read +0.0000523892.

3. The official ICUMSA polynomial is the one given at the 16th Session, which is identical to polynomial (1) of SPS-3. If it is used outside the ranges of 0 to 65 % and 19 to 40 °C the accuracy is reduced.

4. If a sample shows a refractive index, which converts to a concentration above 65 % using the polynomial, it will typically not be a pure sucrose solution. The same applies to samples measured at temperatures outside the range of 19 to 40 °C. For non-pure sucrose solutions, the result will never be the exact concentration, but not more and not less than a reproducible value.

That’s why it is not necessary to restrict the validity range of the scale – above 65 % and 40 °C the point is not accuracy but reproducibility.

5. Some commercially available refractometers do not use the ICUMSA polynomial directly, but manufacturer specific polynomials. This is not a problem, generally, manufacturers are free to choose any conversion procedure they want to use.
But in order to get reproducible results between different instruments, the range of the refractometric concentration scale for sucrose should be limited by the manufacturer to a region where the results are following the ICUMSA polynomial. Otherwise it should be stated clearly in the manual, for which range the sucrose scale is conforms to the ICUMSA.