ICUMSA News n°37 – 1999

Editor: Rud Frik Madsen,

Message from the President

In spite of what I hoped when I drew up ICUMSA News No. 36, I have to advise you that at the present time the Proceedings of the Session held in Berlin are not yet available. Unfortunately, there were some computer problems and some files were lost. These have now been restored and we are trying to make up the lost time.

Although the Proceedings provide an important reference point, I believe that the work of the Referees and Associate Referees can fruitfully proceed even if the Proceedings are not yet available. The reports provided in Berlin plus the publication of the Recommendations in the major journals and via internet (, as well as the provision on the internet of information (postal addresses, phone and fax numbers and e-mail addresses) should in my opinion allow not only regular contact between Referees and Associate Referees but also the continuation of the activity of our Commission. I have already received from a number of Referees the programmes of work they plan to carry out in collaboration with their Associate Referees, and I ask those who have not already done so to send me copies of their programmes.

Apart from the computer problems mentioned above, Phillip Atherton, Chairman of the Publication Committee, points out that: “There is considerable trouble with the incompatibility of imported programmes with those sold here. Text is usually not a problem but there is frequently a problem getting tables and figures across, and sometimes you can get the figures but not the legends and/or captions. I think it is vital that, well before the next Congress, ICUMSA organise standard programmes for text and figures, and forward copies to all authors, with the statement that material not sent in these formats will be returned to the authors to be converted. A tremendous amount of waste time could be avoided if such standardisation could be achieved”. I believe that such a suggestion must be taken into consideration even if it should involve some changes in procedures for the Referees. The aim is to save time saving and reduce costs reduction as far as the publication of the Proceedings is concerned.

I have been informed by our Indian colleagues that they are not only starting the preparation of the next Session in India but are trying to start an interesting initiative intended to make the superintendents of the laboratories of the great number of sugar factories operating in India aware of the ICUMSA analytical methods. In fact Dr Shivade (Vasantada Sugar Institute, Pune, India) informed me as follows: “I am glad to inform you that we are conducting a training programme on ICUMSA METHODS OF SUGAR ANALYSIS on a national level and we got a tremendous response from sugar factory in India. This activity which we started in our Institute is aimed at creating an awareness of ICUMSA amongst Indian Sugar Industry technocrats”. I believe that such an initiative is praiseworthy, and, if they have not already done so, can be taken up by other National Committees.

Those who, on application, received the page dividers for the Methods Book, have advised, that these dividers greatly facilitate the use of the book, giving quick access to the various sections. For logistical reasons we cannot automatically send the page dividers to all the owners of the ICUMSA Methods Book but we emphasise that they can be obtained, free of charge, by contacting the President’s office by fax (+39 0532 291 168) or e-mail (

Progress Report on General Subject 2: White Sugar

Geoff Parkin (UK), Referee for GS2

A work programme based upon responses from GS2 Associate Referees and the Referees of related ICUMSA Subjects is in the course of preparation. This programme accords with those 1998 Recommendations, which fit exactly into the remit of General Subject 2. Other 1998 Recommendations that seem to fit better into some scientific Subjects will, if possible, be followed up in those Subjects, with the agreement of the relevant Referees, as detailed below. 

1. GS2 Work Programme.

Rec.6 calls for further testing of Method GS2/3-19(1996) «The Determination of Insoluble Matter in White Sugar».  Accordingly, this Method is to be collaboratively tested. This time it will use samples made up from a base sample of low insoluble matter white sugar to which will be added known amounts of insoluble matter.

Rec.7 calls for a method for the determination of Acid Beverage Floc to be developed and tested.  Accordingly, a Method will first be written up in collaboration with the major soft drink manufacturers, agreed by the GS2 Associate Referees and then collaboratively tested.

Rec.8 calls for Method GS2/3-23 (1994) «The Determination of Lead and Arsenic in White Sugar by Atomic Absorption Spectroscopy» to be revised as applicable to Arsenic only.  This will be done and the revised Method GS2/3-23 (1999) will then be collaboratively tested.

Rec.9 «Modern AAS methods for the determination of Iron and Copper should be collaboratively tested as a matter of urgency.»: An AAS method for the determination of Iron and Copper is to be selected from the literature or possibly written up, agreed with the GS2 Associate Referees, and collaboratively tested.

2. GS2 Recommendations which will possibly be followed up in collaboration with other Referees.

Rec.1 «The Knight and Allen method for the determination of Reducing Sugars, Method GS2/3-5(1997) should retain its Official status but further testing should be done urgently.»: Because the Knight & Allen Method [Method GS2/3-5(1997)], was designed for application to refined sugars containing reducing sugars contents in the range 0 to 0.017% and its extension to cover higher levels, by adding low-invert sucrose, has not proved to be satisfactory, Mr Ron Plews has agreed to rewrite the method to cover a higher range without the use of low-invert sucrose. My laboratory will test Mr Plews’ modification and if deemed satisfactory, I will ask Dr V S Keskar, the Referee for S.13, whether she will include it in any collaborative work which she carries out.  If the modification proves to be unsatisfactory in our hands, then I will not propose any further testing of this method, unless specifically requested to the contrary.

Rec.4 «Every assistance should be given to the work to find an acceptable replacement for the Braunschweig colour standards. After completion of this work the status of Method GS2-13 should be reviewed.»: The German National Committee has initiated a working group for the study of alternative standards for reflectance measurements and I await the results of their work with interest. If requested by them I will ask the Associate Referees of GS2 to participate in any collaborative testing necessary.

Rec.5 «Visual colour measurement to include the use of Chroma-colorimeters, as proposed by J-P Lescure of the French National Committee and provisionally designated Method GS2-12, should be developed and collaboratively tested in conjunction with the Referee for Subject 7.»: I understand that Dr Wolfgang Kernchen the Referee for Subject 7 is following up this Recommendation and will be discussing the proposal submitted by M J-P Lescure of the French National Committee. Would anyone who is interested in the use of Chroma-colorimeters please contact Dr. Kernchen.

3. Other Recommendations to be followed up.

Recs.2&5, Subject 7: I will be rewriting Method GS2/3-9 in collaboration with the Referees for Subject 7 and General Subject 3. Anyone else wishing to contribute to this task is welcome and should please contact me. The rewritten Methods will first be submitted to the GS2 and GS3 Associate Referees, before they are recommended for adoption

Whilst the above proposals seem to me to be comprehensive, I would welcome any comments at all, particularly before we set to work. Thus, if anyone thinks that I have got it wrong, or that other methods need to be tested, please do let me know. I will then consult with all those involved in the above proposed programme.

Progress Report on General Subject 7: Cane Sugar Processing

Owen Crees (Australia), Referee for GS7

There were two specific recommendations that need to be considered following the Berlin meeting:

The chromatographic methods used in South Africa and Australia to measure lactic acid and ethanol degradation products in process should be investigated to determine whether they can be developed to Accepted status.

Methods for polarisation of cane sugar massecuites and molasses using long wavelength polarimeters should be developed.

As the first recommendation deals with factory degradation products, collaborative testing of juice samples is unlikely to be feasible, but it may be possible to use syrup samples. The possibility of organising a collaborative test will be considered but will proceed only if there is sufficient interest from Associate Referees.

The matter of a new polarisation method for molasses and massecuites is likely to be more difficult. There is considerable interest around the world in removing Pb compounds from laboratories for environmental reasons as well as for general laboratory safety.

Over recent years, there have been numerous attempts to develop non-toxic clarification aids. However, many have been unable to clarify lower purity materials adequately or resulted in unacceptably low filtration rates.  Those that gave adequate clarification produced results that were significantly different from the conventional method, especially with lower purity materials such as molasses. At present, there seems to be little hope of finding an alternative to the lead acetate reagent which gives adequate clarification and decolourisation for a conventional polarimeter without significantly affecting the result but we must continue to seek solutions to this problem.

As reported in Berlin, one Australian factory has been analysing mill juice samples by filtration through a Celite filter aid followed by polarisation at 880 nm. The procedure has been used successfully for several years. However, it has not been applied to more concentrated or more highly coloured materials such as massecuites or molasses.

Polarisation at longer wavelengths means that solutions do not need to be decolourised to the same extent. Solutions must still be free of turbidity, so some form of filtration is still essential. Hence the Celite filtration step referred to above for juice samples. The major problem, however, is likely to be the effect of the different impurities removed by the various reagents. Simple Celite filtration will not remove any soluble impurities, so it would be surprising if there was not a significant difference in results between this method and conventional lead-based methods. Furthermore, because Celite filtration does not remove colour, solutions may still be too dark for most instruments.

An alternative may be the use of NIR transmission spectroscopy for direct measurement of pol in factory process samples. It is a technology that should be investigated further, as it may offer much better prospects than polarisation methods. Routine use of this technology in cane sugar factories appears to be confined to the analysis of juices at present, but there may be opportunities to investigate extension of the technology to other materials.

While the prospects of developing a new method that does not involve the use of Pb compounds but still gives the same results as the current methods seems remote, it is important that investigations of alternative clarifying agents and alternative analytical methods such as NIR spectroscopy continue.