A treatise on ICUMSA solution color – Part 1: Review and outlook

The determination of white sugar solution color, as an important measurement in white sugar quality determination, needs preci-sely defined analytical methods. The paper discusses several problems with this analytical procedure which have not yet been finally resolved by the work of ICUMSA, viz. water quality and preparation of solutions, filtration technique and membrane material, de-aeration and removal of striations from the solution and precautions to avoid instrumental errors. The report gives some recommendations for an update of the current Official method. Furthermore, because color determination has at least two different purposes, first to obtain color balances in the production process and second to determine the quality of finished pro-ducts, it is proposed to establish different methods. To have more than one method per matrix and analyte is current ICUMSA practice and an AOAC recommendation [55]. Whilst formerly ICUMSA used several different methods for the determination of white sugar solution color, since 1990 there is only one official method left, which should be recommended preferably for the first analytical purpose (ICUMSA Method GS 2/3-9 (1994)). Regarding the obvious demand of a large number of sugar ana-lysts, as documented in the ICUMSA Proceedings, it is proposed to re-establish the former ICUMSA Method 4 as Method GS 2/3-10, because it has several practical advantages and because it seems to be better suited for the second purpose. The proposed method, as compared with the Official one, dispenses with pH adjustment and the use of buffer solutions. So it is suited to give a ‘natural’, unmodified solution color, which will be more useful to sugar customers. Furthermore this method saves money, working time and chemicals and reduces disposal problems. Results of an international comparative study of both methods will be presented in Part 2 of this publication.